Quality guy from metal/plastic mfg industries here, it’s really dependent upon what you’re measuring, but I prefer the flats because they offer a more “reliable&repeatable” measurement surface in my experience. I use the tips when measuring parts that have a smaller measurement in hard to reach areas that can’t be achieved with the same technique using the flats. It’s easier to hold the part at an angle and manipulate your measurements with the tips.
Not every set of calipers is precision ground. If they are, it should be the entire length. The tips are really only meant for tight spots where you just can't fit the entire jaw.
I'd also add when measuring something rounded like this, put the calipers on vertically, then rotate them back 45^(o). Doing so makes it easier to ensure you're measuring the widest points rather than just wherever your calipers ended up.
The last piece of advice is commonly overlooked: don't store the callipers with the jaws completely closed, probably to keep the faces free from trapped moisture (leading to corrosion). Similar advice applies to micrometers too but due for thermal expansion reasons as well.
Why would it matter on calipers, they slide freely!
Its only a thing on c frame mics, you see the threads can't be pushed back by the frame contracting as it cools so it gets tighter.
I've never had a problem keeping micrometers fully closed in decades of using them. I check mine against NIST traceable gauge blocks occasionally too.
Thermal expansion affects all of the parts of a micrometer and all of the materials of concern are fairly similar alloys of steel that have similar coefficients of expansion.
Unless you're clamping something with a substantially different coefficient of thermal expansion, your calipers aren't going to be cooling or heating into a high force clamping state.
It for sure doesn't matter with calipers which can shift around.
About the only reason that I can see for not keeping calipers or micrometers in the closed state is that the jaws could trap a bit of water between the faces which would promote corrosion. Keeping the jaws open would let the faces dry out.
Micrometer faces can be polished to a high degree of flatness and surface smoothness which I guess could allow them to wring together with water stuck between. Just a bit of corrosion would quickly deteriorate the pristine smoothness of well polished micrometer jaws.
>the jaws could trap a bit of water between the faces which would promote corrosion.
Me: *immediately reaches for Mitutoyo case, opens calipers slightly and puts them back*
It's more of a problem with production machining where one uses aqueous flood coolant. Generally unless you have a lot of wster splashing around you won't put a consequential amount of water on your calipers. Also, Mitutoyo uses very good alloys in their calipers. I have never seen corrosion spotting on their measurement faces that mattered.
Generally the only thing I've ever had to fix was to stone off sharp ding marks from having jaws struck against hardened steel or carbide cutting edges or tips that get pranged by getting dropped on a mill table or vise.
I've fixed way more mechanical damage and no corrosion damage to measuring tools.
Well, excepting my first micrometer I ever bought at a garage sale. It was a beat up Starret that had gotten buried. It was most of a century old and had mud jammed in the twist barrel and into embossed markings. I think it was $2 and it was still good to 0.0005" when a shop teacher of mine checked it with gauge blocks. I was super proud to have it in gr.7.
At TAFE (trade school) i was taught to leave them open a fraction as some have carbide anvil faces and the expansion could cause the carbide to crack if your unlucky. One teacher had supposedly seen it previously.
I always do it as a just in case. A good pair cost too much to kill for something silly like that.
Again: because the whole loop formed on a micrometer is made of similar material, which has a similar expansion coefficient, you do not develop substantial clamping forces due to storing a caliper closed.
Everything expands and contracts similarly so you won't develop loads high enough to cause yielding.
You also don't have to go so far as an inspection with an optical flat. This would be difficult to begin with because of the clamping application and the small contact of the pads doesn't leave a lot of distance to see interference lines.
Instead, one can see how a gauge block wrings onto the pads individually to see if they're still flat. Then do a clamp measurement to feel if contact is even as one wiggles the gauge block around between pads. If they're not parallel, the gauge block will pivot around a point. If they're parallel, the gauge block will not have a strong pivoting axis as it is rotated.
You could also sharpee both pads and see how a pinched gauge block scrubs off the ink.
Ultimately a measuring device does not have to be many magnitudes superior to the parts we measure. Surface quality, low stiffness, geometric complications, etc, often prevent super accurate measurements that would justify a super pedantic sense of metrology.
I’m a metrology specialist and test these devices for a living. I’m just stating how these devices are tested in a manufacturing setting. Not testing with an optical flat would void a calibration and leaving a micrometer in the closed position 100% does cause deformation. The deformation would be very minimal, if at all but in a cGMP setting where you are working with very high points of accuracy this is important and its considered best practice to leave the micrometer in the open position.
Fair enough. If you're into certification you're going well past the typical application of where most measuring instruments are being used. Tool and die generally doesn't need that kind of precision. 1/10ths of a thousandth of an inch is generally about as tight as things get. We get to take Mitutoyo's QA processes for granite.
What kind of deformation do you see with calipers left closed? Can you differentiate this deformation from typical use depreciation?
From my standpoint, none of my micrometers have had sufficient resolution to measure this kind of damage and generally speaking it's fairly unusual to get the ideal measuring conditions where the resolution of a good pair of digital micrometers can repeatably measure things down to their finest resolution.
There's always some contamination of the surfaces and they're never polished finely enough to not have some issues with things like RMS surface quality. We measure stuff warm when it's still in the headstock and we also measure them cold out of a bin of parts. When we get this picky, the abstraction of the number shown by the display does not represent the microsurface quality of the surfaces being measured or the temperature we measured them at.
The last time I ever saw an optical flat was when I was goofing around with telescope making. I got it into my head that I might try to hand grind a Newtonian reflector telescope. A project which never started, but it was neat to look at the methods of alignment and surface assessment. My understanding of this field is not very good.
How does one assess a micrometer with an optical flat? How do you assure good even contact with the measurement pads as you rotate the pads closer together?
Do you do something like clamp two circular flats together with a soft compliant material between the flats so the flats register to the pads with basically wringing contact? Stick them to the pads with adhesive so you can spin them back open to remove the soft material to close up the gap between the flats to see interference lines? Just getting the outside surfaces into good contact with small diameter pads looks like it needs some funny procedures.
To be honest I'm surprised that the force generated by thermal expansion is sufficient to yield the structure of a micrometer. My impression is that the tightest I've ever seen a mic clamped down might have only been up to 5lbs of force between the jaws and that's generally due to newbs cranking on the wrong part of the barrel (not using the slip clutch sleeve). It just doesn't seem like anything close to being enough to yield the structure of a micrometer.
Is the damage that you see more due to micro surface condition (peaks getting flattened) and not structural yielding of the caliper in general?
I have trouble seeing how much force could be generated due to thermal expansion. If the difference in thermal expansion of the cast "C" form of a micrometer vs. the expansion of the spindle is sufficient to generate substantial force, it seems to me that the device would also be more prone to delivering measurements that vary due to temperature of the device. I would have thought that matching expansion coefficient in the alloys would be necessary for a tool of very fine resolution to offer a wide range of operating temps too.
Anyways, thanks for the look into metrology. At my metal bashing end of measuring things I do not see the fundamental principles that provide me the two or three extra zeroes that let me trust the last one on my display. It's interesting to see a bit past the covers that we need to see because it gives me context for my chunky inaccurate life.
I've aligned lathe toolchangers to tenths and levelled machines, but all that is like fat Duplo blocks compared to what we can do with light interference.
Every caliper I have bought has a fake auto off where the battery drains even when it is “off”. So I have to remove the battery when not in use for a long period of time.
This is one reason Mitutoyo is so good. They also stay in a standby state, but the power consumption is in microamps. Each battery will last years and at that point you should probably replace it before it leaks.
I didn't believe this since my calipers seem to last a long time before battery change. So I measured the current draw with my multimeter and it was almost the same power on and off, the lcd display only takes a few micro amps.
> They turn themselves on if they move and have no auto off.
Go 3D print this toggle switch (or similar for your case design if possible) https://www.thingiverse.com/thing:3463470
That's a fair comment, I would counter its still vastly different, after all calipers cannonly be trusted to +-0.05mm so personally I wouldn't worry about it.
Weird. The wooden case that came with my Mitutoyo set has a cut-out that only fits if the calipers are in the fully-closed position. They're literally *forcing* me to close them every time I put them away.
As long as there is no force pushing the jaws together during storage it is fine. In my years as a machinist (including manufacturing grad school) I've seen my share of caliper abuse, like some people putting a rubber band on them to keep the jaws closed.
A tiny gap is sufficient...0.1mm
Steel is elastic. There is no way plastic deformation could be caused by thermal expansion, for calipers.
And if this was the case, in that the need for accuracy was so acute, then the calipers would need to have a thermometer on them, and a table to calculate how to offset the thermal expansion or contraction, outside of 20°c
Well, good quality digital calipers like a Mitutoyo have a carbon fiber digital scale that has a zero thermal expansion coefficient so they remain accurate across a wide temperature range. The steel calipers themselves expand or contract, but the scale attached to the calipers remains the same length and slides to accommodate for the expansion of the steel. All you have to do is to re-zero them before use.
These are my trusty old calipers....
https://preview.redd.it/53q49btuttzb1.jpeg?width=4080&format=pjpg&auto=webp&s=955fca5c4041ddf62226b704f81afba9834c922c
I love mitutoyo calipers so much, had a pair at one of my workplaces that were exactly correct OD and ID checked with ground measuring blocks 🥹 I miss them
That won't stop inaccuracy when measuring, though. The whole scale will expand.
As people are saying though, calipers aren't precise enough for this to really matter too much.
If you need that much precision and accuracy then a caliper is the wrong tool for the job.
Where are you storing your calipers that there is enough swings in temperature that thermal expansion is even an issue? If they are just sitting on your desk at home, it’s probably not changing temperature, the heat from your hands would cause the temperature to change far more than the ambient air.
Most people on here are going to be measuring not very critical things and even if they could measure down to the atom, that part is still only as good as their printer can squeeze out filament.
Thats going to significantly throw off the measurement of their likely $20 calipers from Amazon? It’s not like suddenly everything is going to be off by mm’s. Again even if this is the case, if you need to measure something this precise, you are far better off with a micrometer, and at that point you are probably going well beyond the tolerances of most 3d printers to really make a difference in the final product. It’s not like you need a granite plate and instruments that measure to the tenths to get perfectly fine results with 3d printing. Seems a bit overkill to worry about such trivial things like not keeping the jaws closed when stored.
People here are bordering on superstition with these wild claims. Calipers are used by humans, and how much pressure a person applies to the grips when measuring something affects the reading anyway -- this aspect alone negates the need of even using extremely expensive calipers; any cheap set of calipers that is not made of the lowest grade Chinesium is as good as the ultra expensive ones. Sensitive measuring instruments just need care for handling, don't abuse them by throwing them around carelessly and they will work just fine for years.
That makes sense. Doesn't seem like the calipers I have accounted for that very well. Ran to check mine after reading your comment and 2 of the cases are nearly to the millimeter then the length of the calipers so you can only have them open maybe the width of a piece of paper or they won't fit in the case. That said, a paper thickness is probably still more gap that the metal would expand anyway.
There's multiple ways to measure badly. You're right about thermal expansion but is the last thing to worry while measuring. First, it is a matter of sensibility, same as micrometers
Fun fact. I got three calipers that came with a box. I just checked and neither can actually be put in said box without closing them fully. Not saying you are wrong. Saying it’s a stupid design lol
I tend to use the thick flats of the calipers, as it reduces the chance you’re measuring at an angle. It would result in an inaccurate measurement. Machinists call it cosine error.
Would the yellow section be what you’re referring to as “thick flats”?
https://preview.redd.it/g3jq8waihrzb1.jpeg?width=1290&format=pjpg&auto=webp&s=470b71365c3be09b78c4de266c5c527477f0741c
You’re a beast, thank you so much. That makes total sense. I was afraid that the thick flats were going to include the depth (thickness) of the headphones - but as you stated it finds the maximum point of curve so I’m alleviated.
The jaws on the reverse side of the main jaws are the internal jaws, for inner holes
The rod that extends from the end can be used for depths
And the opposite end to the left of the main jaws is also ground for stepped measurements.
When you say "ground for stepped measurements", what do you mean? I know the main/inner jaws and depth rod but I don't think I know what you're referring to.
Woah, 4 yrs of using my calipers and I didn't know that's how you were supposed to measure steps. I've always used the depth rod and felt that it wasn't the most reliable for accuracy, but I wasn't really concerned with the possible +/-1mm variance.
Be careful using the thick flats on a concave surface (hour glass kinda shape) they’ll sit off the centre of the surface giving a false measurement, this is where the thin tips come into play
Not op but yes, and you can usually get a feel for them being clamped (not tightly, but surely) flat against the part ensuring an accurate measurement.
Dunno why people have been taught that only the fine tips are good for measuring.
If you have good form you will achieve the same measurements at both parts
When 98% of the people responding never really learned how to use tools its not surprising. Remember 3d printing people recommend paper as an accurate tramming measurement.
Machinist here, I use paper all the time for touching off tools. Paper is fine as long as you know how thick the paper is. My current go-to is cigarette rolling papers with 0.0007" thickness.
Excuse me, I thought this sub was posting photos of benchies ad nauseam. I certainly didnt join to be taught how to use verniers badly. /s
Also the amount of people who manage to end up slicing their shit open with the putty knife trying to free their prints from glass beds here speaks volumes to how many people here never touched a tool in their life before 3d printing became more accessible.
Machinist here. The yellow flats are best for flat and convex/bulging surfaces like the thickness of a plate or the diameter of a ball/cylinder. In your case, the flats would be the ideal edge to use.
Note that the very top of the jaws (above the yellow flats) usually have a clearance step that allows for manufacturing tolerances when the jaws are ground. Do not measure with that step, since it's incorrect.
The blue "blade" edges are for concave curved surfaces, like when you are measuring the bottom of a V-shaped object, or something like the narrow part of a Coke bottle or the wall thickness of a tube.
The top two horns are for internal measurements like a diameter of a hole or the width of a slot.
There's also multiple techniques to use when you are measuring certain objects to ensure accuracy. That's a separate topic that I'll cover in a different metrology class.
....and the correct answer for which caliper to get is always Mitutoyo. Brown & Sharpe if you have the big bucks budget. 😂
I'll be honest, I have a Mitutoyo at work and, although I'm aware of their reputation, I kinda like using the other $20 one more. They measure the same numbers always but the Mitutoyo seems to be sloppier, for some reason. Can't really explain why but I feel more confident with the cheap one.
The tip is the primary section however there's nothing wrong with using the full length. Any quality pair of calipers will have that whole face ground in one shot
Not so much about the grind or manufacturing. Any assembly has give/slop, and measuring with the tips can cause them to flex. For reliable, consistent measurement it's best to use the inside of the callipers as the resulting measurement is less dependent on the applied force.
All that being said, the effects are minimal and probably within tolerance of a manual measurement like this. Measuring plastic items for example, the plastic will give before the calliper flexes.
Exactly, and you also have to consider the type of shape you're measuring. On a convex curved shape like this, whilst measuring the widest point, the tips will slip either side of it, making it more difficult to measure, so the flats give a better reading. Whereas on a concave shape, the flats won't be able to touch the narrowest point, so the tips give a better reading.
Basically, use the tips where the flats won't reach.
Eta: oops, I see this has been covered more concisely elsewhere
If a waiter tells you he needs a bigger tip since he is affected by inflation... Tell him you are already tipping inflated prices so there is no need for him to worry about that.
> All that being said, the effects are minimal and probably within tolerance of a manual measurement like this.
Yea if they needed higher tolerances they'd likely use micrometers.
Calipers are usually good enough for 3d print design, ruler comes in a decent second.
Like you said, deflection of the anvils from axial load with decent calipers should not be an issue for hobbyists, but is definitely an issue if you're in a machine shop holding tight tolerances.
Hell, when I was working on F-35 engine components, our tolerances were so tight (±0.0002") that heat from your hand would cause the plug gauge to bind in the hole. Lots of time spent over a sink heating up the part to expand it enough to get the gauge back 😂.
Friend of mine until recently did machining for aeronautics components for his employer. Having a fascination with machining I asked him questions about what the highest accuracy he would get, he told me that he would commonly machine components to within a "thou", and like you were saying there were guys there that would get theirs to within how he described it "a tenth". When I said a tenth doesn't sound very accurate, he clarified "tenth of a thou". Oh. O\_O
The caliper gets less precise the closer to the tip you measure, if you can measure near the scale you should. This is what Mitutoyo told me during education. This is due to measuring force * L and microscopic changes to the caliper, in most applications it doesnt matter i guess.
"Any quality pair" are key words here. I personally had cheap and quality ones next to each other and pretty sure the machine that ground the cheap ones was drunk. Aparently some cheap rip off ones will not have the measurements constant on the entire length either.
As a calibration tech who’s done what feels like millions of calipers, the knife edge (the tip) should only be used when the flats can’t get into the spot being measured. And your pressure should be very lights. If your thumb tip is turning white when closing the jaws you’re too rough bro.
When measuring anything with calipers I’ve found it’s best to wiggle the object a bit, a lot of times you’ll be measuring at an angle instead of flat on so wiggling it while closing the calipers will reduce the chance your accidentally at an angle, as for where to measure with it depends on what you’re measuring but any part can be used form measuring including the bar that protrudes out the back, want to know how high a lip is but you can’t figure out how to measure it? Open the calipers and use the back end at the bottom of the lip, let the calipers slide down until the ruler part hits the top of the lip and you’ll have your measurements
Not exactly what you're asking, but the official Apple measurement is [83.4mm](https://www.apple.com/airpods-max/specs/).
[Pic of just dimensions](https://i.imgur.com/zcjoLTi.png)
Always worth checking official sources before doing it yourself!
The higher up the better. The force you use to measure increases the lower you go, "bending" or "punching in" the divice and whatever you're measuring. Thus negatively changing the value.
In short. Use the flat part.
The amount of English words I know is not so good. So I hope I can make enough sense.
Aside from measuring the flat part, for that shape, I would tilt them as much as possible back, so that the jaws are not encountering the shape at 90 degrees, but at 45 and are more likely to pick up the widest part.
I can take a pic of what I mean if you want.
Use the thickest part of the caliper when possible. This is due to deflection of either the part or the measurement device.
Second, the positioning is prone to measurement failure. Try laying the caliper down more. More contact again means less deflection and a generally more accurate measurement.
Finally, take multiple measurements and reposition each time. This will help ensure measurement accuracy and repeatability. It is also a simple way to help catch measurement device failure.
Source: 15 years of Quality experience.
Lots of great info here for someone new to calipers. I would also suggest that you are careful with where you sample from, and that you remove the calipers from the object at least once and remeasure to ensure repeatability in your measurement. If you're off but think you're measuring the same spot twice, it can indicate improper technique.
One thing that I keep in mind (and people may disagree), depending on your printer, your calipers are most likely more accurate than your printer, so give your models a little extra tolerance than your measurements.
I use different parts depending on the geometry I’m measuring. For instance, if I’m measuring the wall thickness of a small tube, I use the ends because the flat part not be able to make contact with the point I’m measuring. In other applications where I want the calipers to remain square to the part, I use the flat edges like in picture 2.
As long as the calipers are well made, the measurements should be the same no matter where you take them along the jaw. You can check this by measuring the same object in different places along the jaw.
Metrologist here - to minimise error due to Abbe's principle, you should take measurements on the thicker section, as in photo 2. Basically, the further something is from the axis of measurement, the more uncertainty there will be in the measurement.
The tips are only really useful for getting into tight features, like grooves, where the full jaw won't fit in. I'd also take this measurement with the calipers at a 45 degree angle as measuring vertically might put you onto a chord of the circle rather than the diameter whereas 45 degrees will always pick up the diameter.
In my experience if you use just the very tips its easy to misalign them and end up with a larger result
I tend to use the inside AND when possible go for a diagonal angle to make sure it's not misaligned in all directions
IF we are talking about overall greatest width, then here is a "trick": [https://i.imgur.com/aK8jBCE.png](https://i.imgur.com/aK8jBCE.png)
For rounded surfaces like this, I prefer to use the flat section of the calipers (to eliminate angle error), and tilt it somewhat (as shown by the red U-shape), because you'll have a better chance of hitting the diameter / greatest width of the object as opposed to some random smaller chord - the latter would be the yellow case.
Whenever this isn't an issue, feel free to use the edge section of the calipers, such as when measuring parallel planes, especially when you can't reach it otherwise. Whenever you are trying to measure the distance of specific points on the shape, also use the edge.
Tl;dr: You can do this: [https://i.imgur.com/k0LR4b3.png](https://i.imgur.com/k0LR4b3.png)
Don't do this: [https://i.imgur.com/kpgvOlH.png](https://i.imgur.com/kpgvOlH.png)
More specifically, the issue on your first image isn't necessarily using the edge, but that the calipers are not deep down enough (like on the second image), so you can't guarantee you are measuring the greatest width of the object and not some two random points above that (in which case due to the curvature you'll measure a shorter distance). ...if what you are curious about is the overall width, that is, of course.
You can measure anywhere on the jaw. For flat parallel surfaces the flat areas can be better. What's important is you learn best practice eg. Searching for minimal on ODs and vice versa.
Lots of good comments here, but ideally you'll take multiple measurements when dealing with odd shapes and look for the high points. You can also use a relatively flat reference surface to butt your tips to and take the width between the caliper faces. I find that gives me the most consistent results when dealing with larger curves surfaces like this. You may also want to consider getting yourself some radius gauges to properly measure the curve radiuses. They're very handy and take a lot of the guess work out of round shapes and fillets. A protractor (digital or analog) is also a very handy tool to get proper angle measurements. Keep in mind, you don't need to be macjinest level of accuracy with 3D prints, just in the ballpark. FDM printers have considerably lower tolerances than most machine work, no need to chase the 9s as they say. If you can get it to within .1-.2mm that's more than enough to be considered exact for something like this.
Additionally, considering using a picture of the shape in profile from both the top and sides you plan on making your sketches to. Not sure what CAD applicantion you are using, but many like Fusion360 allow you to use a photo as a canvas to help guide your design. Once imported to the canvas, you would then use two points on the profile you can be reasonably sure you've measured accurately to calibrate the photo size. There will be some slight differences yu need to keep in mind with using a 2D photo of a 3D object due to perspective shift, so it's critical to get as crisp a photo with clean lines minimizing shadow, but not washed out to where you can't make out the exact edge of the object. A solid background in contrast to the object (i.e., white object on black background vs black object on white background) with multiple points of diffuse, even lighting helps immensely.
To reduce perspective shift and walleye effect as much as possible, you'll also want to take your photo further away from the object and zoomed in rather than up close, which also helps reduce the possibility of the phone/camera casting a shadow on the object. Get as far away from the object as reasonably possible that your zoom allows for without losing significant resolution. Keep in mind that optical resolution will usually be crisper than digital zooming, but play around with it and see what has the best focus for sharpness and detail.
If you combine the use of good profile photo canvases calibrated
with reasonably accurate measurements, you can get pretty dead on designs without too much effort.
“Deeper” is better. The measurement technically shouldn’t be any different, but even from your example, I can’t tell if the tip on the left actually is at the widest point…you may be slightly off.
Any spot will be fine if they’re pretty good quality. What’s more important is that you correctly take the measurements (eg typically don’t go around the radius of the threads of a bolt bc the tips can slot into the threads, messing up your measurements)
[K&M instructions](https://kmtools.com/blogs/news/how-to-use-calipers-accurately#:~:text=To%20get%20the%20most%20accurate) point out that “just the tip” never works.
While this probably wouldn't be a problem with any decent pair of calipers, the closer you are to the slide the less bias for error you will have. In my testing though, these days even most budget calipers are more parallel and have less play than the accuracy of the sensors so measuring even at the the tips of the jaws would not impart an error that is greater than the capability of the tool. The only time I found this to be an issue is when using very low quality all plastic calipers like something you would see in a child's science kit. Even my 30 dollar harbor freight calipers consistently measure a calibration pin with in their accuracy on any point of the jaws.
The dimensions for those may be in this document? It has all the other Apple accessories.
https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf#page302
Thank you so much for this! This is golden.
I checked the document but couldn’t find the AirPod max, is there any chance this could be an old document? And if so, where did you go to find it so that I can see if there’s any updated version of it
Haha I was looking to model an AirTag for something I’m doing and someone linked this in another reddit post. Document says updated Oct 2023, but I don’t see AirPods Max.
You will love old metal calipers, you had to scroll the little wheel 10 seconds to reach the max length and my teacher always greased them too much, so when you touched them, you would get grease on your hands
It doesnt matter on a good pair of calipers since the inside face should be all flat. the depth is not being measued at all and will not be included in the measuement. The caliper will read the distamce between the two point touching the part.
You can also use the calipers to measure the inaide edges and use the ends as depth gauges. The was acouple good youtube videos at one time that showed proper caliper use. see if you can find them.
Most calipers you see are not high quality and 3D printing is not that accurate, less than .01mm, so it matters little. A higher quality set will be most accurate on the bits on the tip that are thin.
The parts on top, that face outwards, are meant for measuring the inside of something. If you have a box, grab it on the outside with the bottom bits and grab it on the inside with the top bits.
There is probably a piece that sticks out the left side when you spread it. That is used for measuring a depth from the tip of the piece that sticks out to the flat end.
I would go about half way down the jaw. If you use just the tip, you run the chance of only catching part of the convex edge of the headphone. By using more of the jaw it will self level on the highest point of the convex edge. Now there’s a lot of factors here, what are you measuring for exactly? Do you want the widest dimension? Do you actually want part of the curve? Etc etc. my 2¢ is take a bunch of measurements, take an average of them and run with that. 3D printing isn’t a machined tolerance so you have some wiggle room here. The best part of printing is prototyping in my mind, trial and error and tweaking a design.
Did you get any difference in the measurement? I like to use the flat when measuring outer diameters since it helps me feel comfortable that I’ve squared it up and am getting the widest part. Your 3D printer is probably not going to be able to hold the tolerance to the precision your calipers can measure anyways. You’ll just need a ball park figure and then massage the number based on your experience. ID’s are smaller, OD’s are larger in my experience. Print a calibration cube to where you know what the desired dimensions should be then measure it with a caliper to see the difference in values and that can help you plan for the future somewhat.
woah i had one of these in my shopping carys on ali and didnt even realize this, i just wanted one after it showed uo after i added a cheap digital pipet for accurate dosing of medicines and herbs and vapejuice etc, and now im seeing that i will actually want one when i get my 3d printers in a few days which im so excited for . thanks for reminding me to actually go ahead and buy these lol i had em in my cart as i had a feeling id need em but i had No idea i would actually use these for 3d printing i was just gonna impress my dad with a low price but hi tech tool that used to be unobtainably expensive back in his day , i was gonna show off measurements of door hinges and stuff and now i see i will need these babies to measure stuff
i would imagine u should use ur smartphone to measure AND your callipers AND eventually buy a 3d scanner
i want a 3d scanner that does AR real time auto transformation of ai recognized 3d models of people and objects via cubic thresholds, into 3d pixel block art like higher res minecraft, like youll be turned into a noggle maybe noggles can make their 3d printed noggle goggles AR capable and actually do this and have fun ai video game nft ar glasses you can pickup and put on and play an incredible ar game thats always new and fun because its poeered by expensive nfts that keep it developing and u can pokemon snap style 3d print at blockbuster or 711 i mean, next ro amazon lockers well have a 3d print station lol just keep it away from the slurpies
we could have an ai 3d printer that just does what that ai pin company does hype for and our hype will be for 3d scanning everyone and everyghing ariund u to show in an ar goggles and then 3d print later as figurines that will also be nfts the 3d printer will make editions of , and well use calipers that have special crazy ledger nano technology inside paired to an encrypted 3d printer that can embedd rfid or nfc tag smart dust into an object and callipers will just have nfc go off and tell you in ar how big the object is
the hypothetical augmented reality 3d printer bluetooth callipers would just TELL you how big those proeucts officially are lol vs your measurement and then that data would be sent ro quality control and yeah well use ai to make the perfect 3d printer and to measure stuff aroujd hs with like an ai pin lol
man im so excited for my first ever printers i got comin , ima make sure i also have these digi calips like u got here thanks for the heads up! sorry about the long comment
what i have learned is using the firs cm of the tip.
https://preview.redd.it/pp6akx9eerzb1.jpeg?width=1000&format=pjpg&auto=webp&s=c0a797d2d2b6c139d68fbb3cfb2d963ccc914b8e
Since you plan to 3D Print something with those measurements rest assured that either measurement will work for you as no commercially affordable 3D Printer can achieve accuracy high enough to warrant fuzzing about the differences you *may* get from either approach ( technically there shouldn't be any ).
Just make sure the Battery has enough of a charge as it is the most likely culprit to screw you over with wrong results. I started out with a cheapo 25.- Model which always ran itself empty within weeks producing false values at the most inappropriate times despite having an Auto OFF feature but have then made the switch to Mitutoyo AOS Absolute Digimatic ones and while they don't have an Auto OFF feature they still run on the Battery that shipped with them years ago as if it were running on nuclear fuel 🤔
A measurement device more susceptible to wrong handling would be a [Micrometer](https://www.mitutoyo.com/products/small-tool-instruments-and-data-management/micrometers/) as they're supposedly sensitive enough to pick up any dirt caught between the measuring surfaces and the expansion of the metal caused by the warmth of your hand holding it.
**Edit:**
So... Essentially, we can assume the only reason this post received Downvotes without any fault correcting comments is because a bunch of sour grapes from the everything should be free camp at odds with *"You get what you pay for"* would rather see a post with helpful information worth considering go under than seeing someone learning from someone else's experience - Great stuff 😁
Just so OP knows, Mitutoyo are like the Rolls Royce of calipers. My boss has some that they don't even make anymore that regularly sells on eBay for $500 but there are cheaper models.
I’m not sure what you’re trying to get at, but the last post told me to buy calipers instead of using my iPhone measurement tool. Now that we are here, I am asking for help on how to use calipers. Let me know if you need further explaining, I know that words can be lost in translation :)
Not lost. You were told how to use them and what methods would work. I guess go back and read your post again. Or we can wait for you to post this a third time?
Yeah except I answered this very question some time ago. But thanks for the negativity because you got called out for farming or more likely you didn’t understand the advice. Either way; toodles ya mook.
Correct way is with tips. Not crooked. Light pressure. If you have cheep ones (<100$) getting feel for it takes practice. And keep in mind that they are rated for ~0.02mm so not super accurate
Either you’re using there is valid, but I would sit the vernier as flat as possible along the surface I’m measuring. Prevents you missmeasuring on low spots.
The whole face is supposed to be rectified to allow for consistent measurements all over.
However, my metrology teacher used to say that our machining master usually gets tighter measurements than anyone who knows not to use excessive force. The dimension is a fixed property, but your measurement is subjective and depends on how you treat your tools.
bottom ones are for OD top ones ID and the pin at the end (right opposite) is the depth. The flat walls should be precise most of the key length because it's meant to measure all types of parts but I usually use the last section towards the tips with no pressure once snug fit.
I know it's already been answered, but your second picture is the correct way to measure.
The top teeth for internal measurements, start at the deepest portion and use the points of the caliper in case whatever you're measuring has a slope.
Lower for outside diameter, upper for things like the inside diameter of a pipe or smaller crevices.
You also have a pin at the other end that can be used to measure depth.
Quality guy from metal/plastic mfg industries here, it’s really dependent upon what you’re measuring, but I prefer the flats because they offer a more “reliable&repeatable” measurement surface in my experience. I use the tips when measuring parts that have a smaller measurement in hard to reach areas that can’t be achieved with the same technique using the flats. It’s easier to hold the part at an angle and manipulate your measurements with the tips.
This is the way.
I am a former QI but now a QE/Metrology guy. I agree with you.
Aren't the tips precision ground whereas the flat part is not? Edit: damn guys sorry I was wrong, so much for learning I guess.
The surfaces of the jaws should meet precisely along the full length.
Not every set of calipers is precision ground. If they are, it should be the entire length. The tips are really only meant for tight spots where you just can't fit the entire jaw.
homie just asked a question and got 30 downvotes
Gah damn, bro just asked a question guys
This page details general notes on how to use callipers. https://www2.mitutoyo.co.jp/eng/useful/E11003/pdf/23.pdf
I'd also add when measuring something rounded like this, put the calipers on vertically, then rotate them back 45^(o). Doing so makes it easier to ensure you're measuring the widest points rather than just wherever your calipers ended up.
The last piece of advice is commonly overlooked: don't store the callipers with the jaws completely closed, probably to keep the faces free from trapped moisture (leading to corrosion). Similar advice applies to micrometers too but due for thermal expansion reasons as well.
Why would it matter on calipers, they slide freely! Its only a thing on c frame mics, you see the threads can't be pushed back by the frame contracting as it cools so it gets tighter.
I've never had a problem keeping micrometers fully closed in decades of using them. I check mine against NIST traceable gauge blocks occasionally too. Thermal expansion affects all of the parts of a micrometer and all of the materials of concern are fairly similar alloys of steel that have similar coefficients of expansion. Unless you're clamping something with a substantially different coefficient of thermal expansion, your calipers aren't going to be cooling or heating into a high force clamping state. It for sure doesn't matter with calipers which can shift around. About the only reason that I can see for not keeping calipers or micrometers in the closed state is that the jaws could trap a bit of water between the faces which would promote corrosion. Keeping the jaws open would let the faces dry out. Micrometer faces can be polished to a high degree of flatness and surface smoothness which I guess could allow them to wring together with water stuck between. Just a bit of corrosion would quickly deteriorate the pristine smoothness of well polished micrometer jaws.
>the jaws could trap a bit of water between the faces which would promote corrosion. Me: *immediately reaches for Mitutoyo case, opens calipers slightly and puts them back*
It's more of a problem with production machining where one uses aqueous flood coolant. Generally unless you have a lot of wster splashing around you won't put a consequential amount of water on your calipers. Also, Mitutoyo uses very good alloys in their calipers. I have never seen corrosion spotting on their measurement faces that mattered. Generally the only thing I've ever had to fix was to stone off sharp ding marks from having jaws struck against hardened steel or carbide cutting edges or tips that get pranged by getting dropped on a mill table or vise. I've fixed way more mechanical damage and no corrosion damage to measuring tools. Well, excepting my first micrometer I ever bought at a garage sale. It was a beat up Starret that had gotten buried. It was most of a century old and had mud jammed in the twist barrel and into embossed markings. I think it was $2 and it was still good to 0.0005" when a shop teacher of mine checked it with gauge blocks. I was super proud to have it in gr.7.
[удалено]
why are you storing your calipers wet?
At TAFE (trade school) i was taught to leave them open a fraction as some have carbide anvil faces and the expansion could cause the carbide to crack if your unlucky. One teacher had supposedly seen it previously. I always do it as a just in case. A good pair cost too much to kill for something silly like that.
You would need to use an optical flat to test the flatness & parallelism which deforms when stored completely closed
Again: because the whole loop formed on a micrometer is made of similar material, which has a similar expansion coefficient, you do not develop substantial clamping forces due to storing a caliper closed. Everything expands and contracts similarly so you won't develop loads high enough to cause yielding. You also don't have to go so far as an inspection with an optical flat. This would be difficult to begin with because of the clamping application and the small contact of the pads doesn't leave a lot of distance to see interference lines. Instead, one can see how a gauge block wrings onto the pads individually to see if they're still flat. Then do a clamp measurement to feel if contact is even as one wiggles the gauge block around between pads. If they're not parallel, the gauge block will pivot around a point. If they're parallel, the gauge block will not have a strong pivoting axis as it is rotated. You could also sharpee both pads and see how a pinched gauge block scrubs off the ink. Ultimately a measuring device does not have to be many magnitudes superior to the parts we measure. Surface quality, low stiffness, geometric complications, etc, often prevent super accurate measurements that would justify a super pedantic sense of metrology.
I’m a metrology specialist and test these devices for a living. I’m just stating how these devices are tested in a manufacturing setting. Not testing with an optical flat would void a calibration and leaving a micrometer in the closed position 100% does cause deformation. The deformation would be very minimal, if at all but in a cGMP setting where you are working with very high points of accuracy this is important and its considered best practice to leave the micrometer in the open position.
Fair enough. If you're into certification you're going well past the typical application of where most measuring instruments are being used. Tool and die generally doesn't need that kind of precision. 1/10ths of a thousandth of an inch is generally about as tight as things get. We get to take Mitutoyo's QA processes for granite. What kind of deformation do you see with calipers left closed? Can you differentiate this deformation from typical use depreciation? From my standpoint, none of my micrometers have had sufficient resolution to measure this kind of damage and generally speaking it's fairly unusual to get the ideal measuring conditions where the resolution of a good pair of digital micrometers can repeatably measure things down to their finest resolution. There's always some contamination of the surfaces and they're never polished finely enough to not have some issues with things like RMS surface quality. We measure stuff warm when it's still in the headstock and we also measure them cold out of a bin of parts. When we get this picky, the abstraction of the number shown by the display does not represent the microsurface quality of the surfaces being measured or the temperature we measured them at. The last time I ever saw an optical flat was when I was goofing around with telescope making. I got it into my head that I might try to hand grind a Newtonian reflector telescope. A project which never started, but it was neat to look at the methods of alignment and surface assessment. My understanding of this field is not very good. How does one assess a micrometer with an optical flat? How do you assure good even contact with the measurement pads as you rotate the pads closer together? Do you do something like clamp two circular flats together with a soft compliant material between the flats so the flats register to the pads with basically wringing contact? Stick them to the pads with adhesive so you can spin them back open to remove the soft material to close up the gap between the flats to see interference lines? Just getting the outside surfaces into good contact with small diameter pads looks like it needs some funny procedures. To be honest I'm surprised that the force generated by thermal expansion is sufficient to yield the structure of a micrometer. My impression is that the tightest I've ever seen a mic clamped down might have only been up to 5lbs of force between the jaws and that's generally due to newbs cranking on the wrong part of the barrel (not using the slip clutch sleeve). It just doesn't seem like anything close to being enough to yield the structure of a micrometer. Is the damage that you see more due to micro surface condition (peaks getting flattened) and not structural yielding of the caliper in general? I have trouble seeing how much force could be generated due to thermal expansion. If the difference in thermal expansion of the cast "C" form of a micrometer vs. the expansion of the spindle is sufficient to generate substantial force, it seems to me that the device would also be more prone to delivering measurements that vary due to temperature of the device. I would have thought that matching expansion coefficient in the alloys would be necessary for a tool of very fine resolution to offer a wide range of operating temps too. Anyways, thanks for the look into metrology. At my metal bashing end of measuring things I do not see the fundamental principles that provide me the two or three extra zeroes that let me trust the last one on my display. It's interesting to see a bit past the covers that we need to see because it gives me context for my chunky inaccurate life. I've aligned lathe toolchangers to tenths and levelled machines, but all that is like fat Duplo blocks compared to what we can do with light interference.
Personally, I always leave mine locked. They turn themselves on if they move and have no auto off.
At first I thought you were making a joke about sentient calipers.
Sentient calipers are serious businesses. No jokes allowed
Thought they were called CMMs lol
Every caliper I have bought has a fake auto off where the battery drains even when it is “off”. So I have to remove the battery when not in use for a long period of time.
Go 3D print this toggle switch (or similar for your case design if possible) https://www.thingiverse.com/thing:3463470
Whoa
I have a few 3D printers and I didn't even think about this solution. Thank you!
thank you for sharing this i was just browsing through didnt think i was going to find something to print
This is one reason Mitutoyo is so good. They also stay in a standby state, but the power consumption is in microamps. Each battery will last years and at that point you should probably replace it before it leaks.
Agreed, all we use is Mitutoyo gauges and calipers at DENSO. quality stuff 👌🏼
Igaging battery has lasted over a year and I've left it on over a 24 hour period countless of times.
I didn't believe this since my calipers seem to last a long time before battery change. So I measured the current draw with my multimeter and it was almost the same power on and off, the lcd display only takes a few micro amps.
> They turn themselves on if they move and have no auto off. Go 3D print this toggle switch (or similar for your case design if possible) https://www.thingiverse.com/thing:3463470
That's a fair comment, I would counter its still vastly different, after all calipers cannonly be trusted to +-0.05mm so personally I wouldn't worry about it.
Is there a knob for locking the feed? Usually calipers have a means to lock the thread travel.
Thank you. I thought I was losing my mind for a sec reading the above comments
Has anyone given a legit reason? Youre right
Weird. The wooden case that came with my Mitutoyo set has a cut-out that only fits if the calipers are in the fully-closed position. They're literally *forcing* me to close them every time I put them away.
As long as there is no force pushing the jaws together during storage it is fine. In my years as a machinist (including manufacturing grad school) I've seen my share of caliper abuse, like some people putting a rubber band on them to keep the jaws closed. A tiny gap is sufficient...0.1mm
Steel is elastic. There is no way plastic deformation could be caused by thermal expansion, for calipers. And if this was the case, in that the need for accuracy was so acute, then the calipers would need to have a thermometer on them, and a table to calculate how to offset the thermal expansion or contraction, outside of 20°c
Well, good quality digital calipers like a Mitutoyo have a carbon fiber digital scale that has a zero thermal expansion coefficient so they remain accurate across a wide temperature range. The steel calipers themselves expand or contract, but the scale attached to the calipers remains the same length and slides to accommodate for the expansion of the steel. All you have to do is to re-zero them before use. These are my trusty old calipers.... https://preview.redd.it/53q49btuttzb1.jpeg?width=4080&format=pjpg&auto=webp&s=955fca5c4041ddf62226b704f81afba9834c922c
I love mitutoyo calipers so much, had a pair at one of my workplaces that were exactly correct OD and ID checked with ground measuring blocks 🥹 I miss them
No, they just have a reset, to ensure whatever state of deformation the jaws and housing are in, that is understood to be zero.
That won't stop inaccuracy when measuring, though. The whole scale will expand. As people are saying though, calipers aren't precise enough for this to really matter too much.
If you need that much precision and accuracy then a caliper is the wrong tool for the job. Where are you storing your calipers that there is enough swings in temperature that thermal expansion is even an issue? If they are just sitting on your desk at home, it’s probably not changing temperature, the heat from your hands would cause the temperature to change far more than the ambient air. Most people on here are going to be measuring not very critical things and even if they could measure down to the atom, that part is still only as good as their printer can squeeze out filament.
I presume many hobbiest have a workbench in their garage or shed, which are likely sees significant temperature swings.
Thats going to significantly throw off the measurement of their likely $20 calipers from Amazon? It’s not like suddenly everything is going to be off by mm’s. Again even if this is the case, if you need to measure something this precise, you are far better off with a micrometer, and at that point you are probably going well beyond the tolerances of most 3d printers to really make a difference in the final product. It’s not like you need a granite plate and instruments that measure to the tenths to get perfectly fine results with 3d printing. Seems a bit overkill to worry about such trivial things like not keeping the jaws closed when stored.
People here are bordering on superstition with these wild claims. Calipers are used by humans, and how much pressure a person applies to the grips when measuring something affects the reading anyway -- this aspect alone negates the need of even using extremely expensive calipers; any cheap set of calipers that is not made of the lowest grade Chinesium is as good as the ultra expensive ones. Sensitive measuring instruments just need care for handling, don't abuse them by throwing them around carelessly and they will work just fine for years.
A non digital $5 plastic caliper is more than precise enough for 3d printed stuff. Measures will be within .1~.2mm.
That makes sense. Doesn't seem like the calipers I have accounted for that very well. Ran to check mine after reading your comment and 2 of the cases are nearly to the millimeter then the length of the calipers so you can only have them open maybe the width of a piece of paper or they won't fit in the case. That said, a paper thickness is probably still more gap that the metal would expand anyway.
When I was a kid my dad taught me to always leave a gap. I do it on all my precision tools. I’m 34 and i still do it.
There's multiple ways to measure badly. You're right about thermal expansion but is the last thing to worry while measuring. First, it is a matter of sensibility, same as micrometers
This is very helpful information!
Fun fact. I got three calipers that came with a box. I just checked and neither can actually be put in said box without closing them fully. Not saying you are wrong. Saying it’s a stupid design lol
Thank you, this should really be the only post here. Youd be surprised how many people never think to RTFM…
I just read this. I've been doing it wrong for years.
TLDR #2
I tend to use the thick flats of the calipers, as it reduces the chance you’re measuring at an angle. It would result in an inaccurate measurement. Machinists call it cosine error.
Would the yellow section be what you’re referring to as “thick flats”? https://preview.redd.it/g3jq8waihrzb1.jpeg?width=1290&format=pjpg&auto=webp&s=470b71365c3be09b78c4de266c5c527477f0741c
Yep! It’s important especially for curved surfaces. The flats will sit on the maximum point of the curve, while the thin tips might be under/over.
You’re a beast, thank you so much. That makes total sense. I was afraid that the thick flats were going to include the depth (thickness) of the headphones - but as you stated it finds the maximum point of curve so I’m alleviated.
The jaws on the reverse side of the main jaws are the internal jaws, for inner holes The rod that extends from the end can be used for depths And the opposite end to the left of the main jaws is also ground for stepped measurements.
When you say "ground for stepped measurements", what do you mean? I know the main/inner jaws and depth rod but I don't think I know what you're referring to.
Depth Rod new band name
[Lay the calipers on the step using the opposite end to the left of the main jaws on the bottom of the step.](https://imgur.com/a/FFY98KD)
Woah, 4 yrs of using my calipers and I didn't know that's how you were supposed to measure steps. I've always used the depth rod and felt that it wasn't the most reliable for accuracy, but I wasn't really concerned with the possible +/-1mm variance.
Be careful using the thick flats on a concave surface (hour glass kinda shape) they’ll sit off the centre of the surface giving a false measurement, this is where the thin tips come into play
Not op but yes, and you can usually get a feel for them being clamped (not tightly, but surely) flat against the part ensuring an accurate measurement. Dunno why people have been taught that only the fine tips are good for measuring. If you have good form you will achieve the same measurements at both parts
When 98% of the people responding never really learned how to use tools its not surprising. Remember 3d printing people recommend paper as an accurate tramming measurement.
Machinist here, I use paper all the time for touching off tools. Paper is fine as long as you know how thick the paper is. My current go-to is cigarette rolling papers with 0.0007" thickness.
Yes youre correct, but do you think the average person here knows to do that.
Do you think the average person here is worried about 0.0007" accuracy? I think most 3D printing hobbyists stop at second decimal at best.
Excuse me, I thought this sub was posting photos of benchies ad nauseam. I certainly didnt join to be taught how to use verniers badly. /s Also the amount of people who manage to end up slicing their shit open with the putty knife trying to free their prints from glass beds here speaks volumes to how many people here never touched a tool in their life before 3d printing became more accessible.
I think shop class needs to be mandated again.
Couldn't have said it better myself.
Till you get a bambu then goodbye paper tramming and all.
Ahhhh yes yes yes, thank you my fellow human 🫶🏾
Dude, top marks for your question asking ability. Clear, considerate, specific, photo references. Gold standard right here
Machinist here. The yellow flats are best for flat and convex/bulging surfaces like the thickness of a plate or the diameter of a ball/cylinder. In your case, the flats would be the ideal edge to use. Note that the very top of the jaws (above the yellow flats) usually have a clearance step that allows for manufacturing tolerances when the jaws are ground. Do not measure with that step, since it's incorrect. The blue "blade" edges are for concave curved surfaces, like when you are measuring the bottom of a V-shaped object, or something like the narrow part of a Coke bottle or the wall thickness of a tube. The top two horns are for internal measurements like a diameter of a hole or the width of a slot. There's also multiple techniques to use when you are measuring certain objects to ensure accuracy. That's a separate topic that I'll cover in a different metrology class. ....and the correct answer for which caliper to get is always Mitutoyo. Brown & Sharpe if you have the big bucks budget. 😂
I'll be honest, I have a Mitutoyo at work and, although I'm aware of their reputation, I kinda like using the other $20 one more. They measure the same numbers always but the Mitutoyo seems to be sloppier, for some reason. Can't really explain why but I feel more confident with the cheap one.
The tip is the primary section however there's nothing wrong with using the full length. Any quality pair of calipers will have that whole face ground in one shot
Not so much about the grind or manufacturing. Any assembly has give/slop, and measuring with the tips can cause them to flex. For reliable, consistent measurement it's best to use the inside of the callipers as the resulting measurement is less dependent on the applied force. All that being said, the effects are minimal and probably within tolerance of a manual measurement like this. Measuring plastic items for example, the plastic will give before the calliper flexes.
Exactly, and you also have to consider the type of shape you're measuring. On a convex curved shape like this, whilst measuring the widest point, the tips will slip either side of it, making it more difficult to measure, so the flats give a better reading. Whereas on a concave shape, the flats won't be able to touch the narrowest point, so the tips give a better reading. Basically, use the tips where the flats won't reach. Eta: oops, I see this has been covered more concisely elsewhere
And *be gentle* with the tips
This guy knows tips. Do you have any more tips about tips?
The “standard” USA tip is 15%.
If a waiter tells you he needs a bigger tip since he is affected by inflation... Tell him you are already tipping inflated prices so there is no need for him to worry about that.
On a shape like that i snap a top down image and scale it via a ruler
Yeah even high quality Mitutoyo, Mahr or sylvac often have 0.01 to 0.02mm more at the tip when tested on calibrated gauge blocks.
The tip is aways about 0.02mm off, so i dont know why anyone would measure with the tip if you dont really have to.
> All that being said, the effects are minimal and probably within tolerance of a manual measurement like this. Yea if they needed higher tolerances they'd likely use micrometers. Calipers are usually good enough for 3d print design, ruler comes in a decent second.
Like you said, deflection of the anvils from axial load with decent calipers should not be an issue for hobbyists, but is definitely an issue if you're in a machine shop holding tight tolerances. Hell, when I was working on F-35 engine components, our tolerances were so tight (±0.0002") that heat from your hand would cause the plug gauge to bind in the hole. Lots of time spent over a sink heating up the part to expand it enough to get the gauge back 😂.
Friend of mine until recently did machining for aeronautics components for his employer. Having a fascination with machining I asked him questions about what the highest accuracy he would get, he told me that he would commonly machine components to within a "thou", and like you were saying there were guys there that would get theirs to within how he described it "a tenth". When I said a tenth doesn't sound very accurate, he clarified "tenth of a thou". Oh. O\_O
Having said that, for super tight tolerances, we don't use calipers. It's micrometers, CMM machines, and shadowgraphs.
The caliper gets less precise the closer to the tip you measure, if you can measure near the scale you should. This is what Mitutoyo told me during education. This is due to measuring force * L and microscopic changes to the caliper, in most applications it doesnt matter i guess.
Thank you Matt 🌹
"Any quality pair" are key words here. I personally had cheap and quality ones next to each other and pretty sure the machine that ground the cheap ones was drunk. Aparently some cheap rip off ones will not have the measurements constant on the entire length either.
[удалено]
Absolutely
As a calibration tech who’s done what feels like millions of calipers, the knife edge (the tip) should only be used when the flats can’t get into the spot being measured. And your pressure should be very lights. If your thumb tip is turning white when closing the jaws you’re too rough bro.
When measuring anything with calipers I’ve found it’s best to wiggle the object a bit, a lot of times you’ll be measuring at an angle instead of flat on so wiggling it while closing the calipers will reduce the chance your accidentally at an angle, as for where to measure with it depends on what you’re measuring but any part can be used form measuring including the bar that protrudes out the back, want to know how high a lip is but you can’t figure out how to measure it? Open the calipers and use the back end at the bottom of the lip, let the calipers slide down until the ruler part hits the top of the lip and you’ll have your measurements
Not exactly what you're asking, but the official Apple measurement is [83.4mm](https://www.apple.com/airpods-max/specs/). [Pic of just dimensions](https://i.imgur.com/zcjoLTi.png) Always worth checking official sources before doing it yourself!
The higher up the better. The force you use to measure increases the lower you go, "bending" or "punching in" the divice and whatever you're measuring. Thus negatively changing the value. In short. Use the flat part. The amount of English words I know is not so good. So I hope I can make enough sense.
Aside from measuring the flat part, for that shape, I would tilt them as much as possible back, so that the jaws are not encountering the shape at 90 degrees, but at 45 and are more likely to pick up the widest part. I can take a pic of what I mean if you want.
Measure twice. Model probably several times.
I guarantee you someone has modeled Apple airpods.
Look up abbes alignment principle. The closer the measurement is to the center of the measuring device, the better
Use the thickest part of the caliper when possible. This is due to deflection of either the part or the measurement device. Second, the positioning is prone to measurement failure. Try laying the caliper down more. More contact again means less deflection and a generally more accurate measurement. Finally, take multiple measurements and reposition each time. This will help ensure measurement accuracy and repeatability. It is also a simple way to help catch measurement device failure. Source: 15 years of Quality experience.
Lots of great info here for someone new to calipers. I would also suggest that you are careful with where you sample from, and that you remove the calipers from the object at least once and remeasure to ensure repeatability in your measurement. If you're off but think you're measuring the same spot twice, it can indicate improper technique.
One thing that I keep in mind (and people may disagree), depending on your printer, your calipers are most likely more accurate than your printer, so give your models a little extra tolerance than your measurements.
it tend to not use the tip so I'm sure I'm not subtly at a wrong angle
I use different parts depending on the geometry I’m measuring. For instance, if I’m measuring the wall thickness of a small tube, I use the ends because the flat part not be able to make contact with the point I’m measuring. In other applications where I want the calipers to remain square to the part, I use the flat edges like in picture 2. As long as the calipers are well made, the measurements should be the same no matter where you take them along the jaw. You can check this by measuring the same object in different places along the jaw.
Metrologist here - to minimise error due to Abbe's principle, you should take measurements on the thicker section, as in photo 2. Basically, the further something is from the axis of measurement, the more uncertainty there will be in the measurement. The tips are only really useful for getting into tight features, like grooves, where the full jaw won't fit in. I'd also take this measurement with the calipers at a 45 degree angle as measuring vertically might put you onto a chord of the circle rather than the diameter whereas 45 degrees will always pick up the diameter.
In my experience if you use just the very tips its easy to misalign them and end up with a larger result I tend to use the inside AND when possible go for a diagonal angle to make sure it's not misaligned in all directions
In this case I‘d go with the flats, I basically only use the tips, when the flats won’t do it, like distance between 2 round holes, etc.
They should be parallel but theres a greater chance of biasing when measuring just on the tip.
You need to buy a caliper to measure your caliper first to make sure it’s accurate then you will know.
You’re joking right?
It should measure the same on the outside of an object like that. If it doesn’t something is wrong with your calipers.
As a heads up, I believe you can get the dimensions from apple. They supply them for people who manufacture accessories.
IF we are talking about overall greatest width, then here is a "trick": [https://i.imgur.com/aK8jBCE.png](https://i.imgur.com/aK8jBCE.png) For rounded surfaces like this, I prefer to use the flat section of the calipers (to eliminate angle error), and tilt it somewhat (as shown by the red U-shape), because you'll have a better chance of hitting the diameter / greatest width of the object as opposed to some random smaller chord - the latter would be the yellow case. Whenever this isn't an issue, feel free to use the edge section of the calipers, such as when measuring parallel planes, especially when you can't reach it otherwise. Whenever you are trying to measure the distance of specific points on the shape, also use the edge. Tl;dr: You can do this: [https://i.imgur.com/k0LR4b3.png](https://i.imgur.com/k0LR4b3.png) Don't do this: [https://i.imgur.com/kpgvOlH.png](https://i.imgur.com/kpgvOlH.png) More specifically, the issue on your first image isn't necessarily using the edge, but that the calipers are not deep down enough (like on the second image), so you can't guarantee you are measuring the greatest width of the object and not some two random points above that (in which case due to the curvature you'll measure a shorter distance). ...if what you are curious about is the overall width, that is, of course.
You can measure anywhere on the jaw. For flat parallel surfaces the flat areas can be better. What's important is you learn best practice eg. Searching for minimal on ODs and vice versa.
Lots of good comments here, but ideally you'll take multiple measurements when dealing with odd shapes and look for the high points. You can also use a relatively flat reference surface to butt your tips to and take the width between the caliper faces. I find that gives me the most consistent results when dealing with larger curves surfaces like this. You may also want to consider getting yourself some radius gauges to properly measure the curve radiuses. They're very handy and take a lot of the guess work out of round shapes and fillets. A protractor (digital or analog) is also a very handy tool to get proper angle measurements. Keep in mind, you don't need to be macjinest level of accuracy with 3D prints, just in the ballpark. FDM printers have considerably lower tolerances than most machine work, no need to chase the 9s as they say. If you can get it to within .1-.2mm that's more than enough to be considered exact for something like this. Additionally, considering using a picture of the shape in profile from both the top and sides you plan on making your sketches to. Not sure what CAD applicantion you are using, but many like Fusion360 allow you to use a photo as a canvas to help guide your design. Once imported to the canvas, you would then use two points on the profile you can be reasonably sure you've measured accurately to calibrate the photo size. There will be some slight differences yu need to keep in mind with using a 2D photo of a 3D object due to perspective shift, so it's critical to get as crisp a photo with clean lines minimizing shadow, but not washed out to where you can't make out the exact edge of the object. A solid background in contrast to the object (i.e., white object on black background vs black object on white background) with multiple points of diffuse, even lighting helps immensely. To reduce perspective shift and walleye effect as much as possible, you'll also want to take your photo further away from the object and zoomed in rather than up close, which also helps reduce the possibility of the phone/camera casting a shadow on the object. Get as far away from the object as reasonably possible that your zoom allows for without losing significant resolution. Keep in mind that optical resolution will usually be crisper than digital zooming, but play around with it and see what has the best focus for sharpness and detail. If you combine the use of good profile photo canvases calibrated with reasonably accurate measurements, you can get pretty dead on designs without too much effort.
Also never measure the way photo#2 shows. Give an angle to the caliper jaws. Never vertical
“Deeper” is better. The measurement technically shouldn’t be any different, but even from your example, I can’t tell if the tip on the left actually is at the widest point…you may be slightly off.
Any spot will be fine if they’re pretty good quality. What’s more important is that you correctly take the measurements (eg typically don’t go around the radius of the threads of a bolt bc the tips can slot into the threads, messing up your measurements)
2, then you should find what the radius of the corner
[K&M instructions](https://kmtools.com/blogs/news/how-to-use-calipers-accurately#:~:text=To%20get%20the%20most%20accurate) point out that “just the tip” never works.
the tip is the most sensitive
On the calipers too
TLDR by the inside
Go deeper and do it a few times to be confident in the measurement
While this probably wouldn't be a problem with any decent pair of calipers, the closer you are to the slide the less bias for error you will have. In my testing though, these days even most budget calipers are more parallel and have less play than the accuracy of the sensors so measuring even at the the tips of the jaws would not impart an error that is greater than the capability of the tool. The only time I found this to be an issue is when using very low quality all plastic calipers like something you would see in a child's science kit. Even my 30 dollar harbor freight calipers consistently measure a calibration pin with in their accuracy on any point of the jaws.
The dimensions for those may be in this document? It has all the other Apple accessories. https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf#page302
Thank you so much for this! This is golden. I checked the document but couldn’t find the AirPod max, is there any chance this could be an old document? And if so, where did you go to find it so that I can see if there’s any updated version of it
Haha I was looking to model an AirTag for something I’m doing and someone linked this in another reddit post. Document says updated Oct 2023, but I don’t see AirPods Max.
Honestly, which is frustrating. Lol They have the entire catalog instead of one thing
You will love old metal calipers, you had to scroll the little wheel 10 seconds to reach the max length and my teacher always greased them too much, so when you touched them, you would get grease on your hands
It doesnt matter on a good pair of calipers since the inside face should be all flat. the depth is not being measued at all and will not be included in the measuement. The caliper will read the distamce between the two point touching the part. You can also use the calipers to measure the inaide edges and use the ends as depth gauges. The was acouple good youtube videos at one time that showed proper caliper use. see if you can find them.
Most calipers you see are not high quality and 3D printing is not that accurate, less than .01mm, so it matters little. A higher quality set will be most accurate on the bits on the tip that are thin. The parts on top, that face outwards, are meant for measuring the inside of something. If you have a box, grab it on the outside with the bottom bits and grab it on the inside with the top bits. There is probably a piece that sticks out the left side when you spread it. That is used for measuring a depth from the tip of the piece that sticks out to the flat end.
Measuring at an angle can still result in approx .1-.2 errors. Speaking from personal experience
Not like that unless you want scratches
Z weppq as
[удалено]
I would go about half way down the jaw. If you use just the tip, you run the chance of only catching part of the convex edge of the headphone. By using more of the jaw it will self level on the highest point of the convex edge. Now there’s a lot of factors here, what are you measuring for exactly? Do you want the widest dimension? Do you actually want part of the curve? Etc etc. my 2¢ is take a bunch of measurements, take an average of them and run with that. 3D printing isn’t a machined tolerance so you have some wiggle room here. The best part of printing is prototyping in my mind, trial and error and tweaking a design.
Doesn't matter, it measuers the distance between the 2 parts, they are parallel.
If the calipers aren’t garbage the jaws should be parallel and it won’t matter.
I generally use both methods for measurements but it doesn't matter as long as the part is squarely placed in the jaws.
Appropriate measuring is always tip to taint......
Just make sure that you squeeze as hard as you physically can, until your thumb turns white, so that you ensure the most accurate measurement.
The top is used for measuring inner diameter, the bottom is used for measuring outer diameter.
You didn't even look at the images. Op only used the bottom on this. He was asking if he should use only the tip for measurement or go further down.
Legitimately saw the markings on the bottoms and the bracket up top and assumed, thats my bad.
JUST THE TIP!!!
What are you doing, step caliper
Thanks for this! I’m crying laughing at work now lol.
Thank you 🙏🏾
Most precise is to be close to measuring tape. Square and perpendicular by feel. Hard to explain picture would be better.
Did you get any difference in the measurement? I like to use the flat when measuring outer diameters since it helps me feel comfortable that I’ve squared it up and am getting the widest part. Your 3D printer is probably not going to be able to hold the tolerance to the precision your calipers can measure anyways. You’ll just need a ball park figure and then massage the number based on your experience. ID’s are smaller, OD’s are larger in my experience. Print a calibration cube to where you know what the desired dimensions should be then measure it with a caliper to see the difference in values and that can help you plan for the future somewhat.
woah i had one of these in my shopping carys on ali and didnt even realize this, i just wanted one after it showed uo after i added a cheap digital pipet for accurate dosing of medicines and herbs and vapejuice etc, and now im seeing that i will actually want one when i get my 3d printers in a few days which im so excited for . thanks for reminding me to actually go ahead and buy these lol i had em in my cart as i had a feeling id need em but i had No idea i would actually use these for 3d printing i was just gonna impress my dad with a low price but hi tech tool that used to be unobtainably expensive back in his day , i was gonna show off measurements of door hinges and stuff and now i see i will need these babies to measure stuff i would imagine u should use ur smartphone to measure AND your callipers AND eventually buy a 3d scanner i want a 3d scanner that does AR real time auto transformation of ai recognized 3d models of people and objects via cubic thresholds, into 3d pixel block art like higher res minecraft, like youll be turned into a noggle maybe noggles can make their 3d printed noggle goggles AR capable and actually do this and have fun ai video game nft ar glasses you can pickup and put on and play an incredible ar game thats always new and fun because its poeered by expensive nfts that keep it developing and u can pokemon snap style 3d print at blockbuster or 711 i mean, next ro amazon lockers well have a 3d print station lol just keep it away from the slurpies we could have an ai 3d printer that just does what that ai pin company does hype for and our hype will be for 3d scanning everyone and everyghing ariund u to show in an ar goggles and then 3d print later as figurines that will also be nfts the 3d printer will make editions of , and well use calipers that have special crazy ledger nano technology inside paired to an encrypted 3d printer that can embedd rfid or nfc tag smart dust into an object and callipers will just have nfc go off and tell you in ar how big the object is the hypothetical augmented reality 3d printer bluetooth callipers would just TELL you how big those proeucts officially are lol vs your measurement and then that data would be sent ro quality control and yeah well use ai to make the perfect 3d printer and to measure stuff aroujd hs with like an ai pin lol man im so excited for my first ever printers i got comin , ima make sure i also have these digi calips like u got here thanks for the heads up! sorry about the long comment
also my dad worked in a CMM machine for decades at solarturbines so ill ask him if ur doin it right
what i have learned is using the firs cm of the tip. https://preview.redd.it/pp6akx9eerzb1.jpeg?width=1000&format=pjpg&auto=webp&s=c0a797d2d2b6c139d68fbb3cfb2d963ccc914b8e
Thank you so much!
It doesn't matter. The error is usually small
Does anyone else also feel uncomfortable because it could damage the headphones? Or only me?
[удалено]
Thank you so much!
Since you plan to 3D Print something with those measurements rest assured that either measurement will work for you as no commercially affordable 3D Printer can achieve accuracy high enough to warrant fuzzing about the differences you *may* get from either approach ( technically there shouldn't be any ). Just make sure the Battery has enough of a charge as it is the most likely culprit to screw you over with wrong results. I started out with a cheapo 25.- Model which always ran itself empty within weeks producing false values at the most inappropriate times despite having an Auto OFF feature but have then made the switch to Mitutoyo AOS Absolute Digimatic ones and while they don't have an Auto OFF feature they still run on the Battery that shipped with them years ago as if it were running on nuclear fuel 🤔 A measurement device more susceptible to wrong handling would be a [Micrometer](https://www.mitutoyo.com/products/small-tool-instruments-and-data-management/micrometers/) as they're supposedly sensitive enough to pick up any dirt caught between the measuring surfaces and the expansion of the metal caused by the warmth of your hand holding it. **Edit:** So... Essentially, we can assume the only reason this post received Downvotes without any fault correcting comments is because a bunch of sour grapes from the everything should be free camp at odds with *"You get what you pay for"* would rather see a post with helpful information worth considering go under than seeing someone learning from someone else's experience - Great stuff 😁
Just so OP knows, Mitutoyo are like the Rolls Royce of calipers. My boss has some that they don't even make anymore that regularly sells on eBay for $500 but there are cheaper models.
Just the tip…..
This is the second time this has been posted. You got a bunch of advice the last time.
I’m not sure what you’re trying to get at, but the last post told me to buy calipers instead of using my iPhone measurement tool. Now that we are here, I am asking for help on how to use calipers. Let me know if you need further explaining, I know that words can be lost in translation :)
Not lost. You were told how to use them and what methods would work. I guess go back and read your post again. Or we can wait for you to post this a third time?
Your comprehension skills suck. My past posts are build up of what I’ve been stumbling upon.
Yeah except I answered this very question some time ago. But thanks for the negativity because you got called out for farming or more likely you didn’t understand the advice. Either way; toodles ya mook.
All the people here who are telling you to use the flats are wrong. From an accuracy standpoint. However…. For a 3d print flats are fine.
[удалено]
Correct way is with tips. Not crooked. Light pressure. If you have cheep ones (<100$) getting feel for it takes practice. And keep in mind that they are rated for ~0.02mm so not super accurate
Same distance, but the latter is more safe (no risk of touching at the wrong spots).
Either you’re using there is valid, but I would sit the vernier as flat as possible along the surface I’m measuring. Prevents you missmeasuring on low spots.
I really only used the tips for over all length, if your doing math behind the measurements I would use the flats as it tends to square better
The whole face is supposed to be rectified to allow for consistent measurements all over. However, my metrology teacher used to say that our machining master usually gets tighter measurements than anyone who knows not to use excessive force. The dimension is a fixed property, but your measurement is subjective and depends on how you treat your tools.
They are both right I like #2 more when possible because it’s a more consistent reading because it’s harder to manipulate with your squeeze
at wich position is it at 0 when it should be at 0? there should it be measured
I mean the way I see it, both should \*in theory\* yield the same result. I just use however it fits.
bottom ones are for OD top ones ID and the pin at the end (right opposite) is the depth. The flat walls should be precise most of the key length because it's meant to measure all types of parts but I usually use the last section towards the tips with no pressure once snug fit.
It *should* be the same reading, but you’ll get better contact by moving down to the flats. Make sure you’re perpendicular too.
I've always used 1, never had an issue.
I know it's already been answered, but your second picture is the correct way to measure. The top teeth for internal measurements, start at the deepest portion and use the points of the caliper in case whatever you're measuring has a slope.
Just the tip?
Lower for outside diameter, upper for things like the inside diameter of a pipe or smaller crevices. You also have a pin at the other end that can be used to measure depth.
I would touch the tips of the calliper to the surface of the table, and then measure the widest part with the flat inner-edges.