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Does anyone have experience using a Mitutoyo High Accuracy Micrometer?

ttrager

Aluminum
Joined
Jul 23, 2015
This would be the Mitutoyo 293-130-10 High Accuracy Digimatic Micrometer.

If you have one, what are your impressions?

Thanks in advance.
 

Cyclotronguy

Stainless
Joined
Sep 21, 2005
Location
Northern California
Pretty spendy. But it seems OK, at least it agrees with gauge blocks. Pretty sure the resolution is better than the actual accuracy.
Bottom line, don't abuse it and check it often against a known standard.

The form factor encourages people to assume it's a common mic to just knock about, it's not.
 

ballen

Titanium
Joined
Sep 25, 2011
Location
Garbsen, Germany
That's a remarkable tool, 100nm resolution and 500nm instrumental error. That error is about the wavelength of visible light. Assuming that it's made from steel, a 2 Celsius differential in temperature between handle and probe shaft will expand the gap between the tips ~500nm. A 0.4 Celsius differential will expand the gap by 100nm, the resolution of the instrument. So it's not trivial to operate at the instrumental error level!

Edit: here's a video about it
https://youtu.be/z27zFsMtkjo
 
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ttrager

Aluminum
Joined
Jul 23, 2015
Pretty spendy. But it seems OK, at least it agrees with gauge blocks. Pretty sure the resolution is better than the actual accuracy.
Bottom line, don't abuse it and check it often against a known standard.

The form factor encourages people to assume it's a common mic to just knock about, it's not.

The one demo vid I remember had the fellows using a mic-stand to eliminate body-heat altering results. Because of the price I decided to double-check my urge to buy stuff by checking with real people who may be using one.

Thanks to you and ballen for the responses.
 

jccaclimber

Hot Rolled
Joined
Nov 22, 2015
Location
San Francisco
Pretty spendy. But it seems OK, at least it agrees with gauge blocks. Pretty sure the resolution is better than the actual accuracy.
Bottom line, don't abuse it and check it often against a known standard.

The form factor encourages people to assume it's a common mic to just knock about, it's not.
Correct, this is noted in the product literature. This is also true of their normal digital micrometers which typically read to 0.001 mm but have +/- 0.00125 mm (inch to mm approximation there) stated accuracy.

This would be the Mitutoyo 293-130-10 High Accuracy Digimatic Micrometer.

If you have one, what are your impressions?

Thanks in advance.

Have one, and like it. Like any other micrometer you have to keep it clean, zero it, gradually approach contact, and click over the ratchet at a consistent rate. I keep the larger plastic barrier around it, and tend to keep it in a micrometer stand whenever possible. Doing those things I've always found it to perform well within its rated accuracy when checking gauge pins, blocks, etc. It is worth noting that the definition of "keep it clean" is a bit more stringent at this level than when measuring a +/- 0.01 mm tolerance, but it's not an order of magnitude more difficult.

One thing worth noting is that the anvils are chamfered so the contact area is smaller than a normal micrometer. This means you can't quite measure up to a shoulder. It also means that if you're trying to measure something compressible you're going to get an artificially low value as your sample compresses. If you're just measuring solid metal components this won't be an issue.

One related cool story: I was measuring bearing IDs and had one that could go on one end of a class Z gauge pin, but not the other. Using the mic. we discovered that the pin had some barrel and taper error adding to about 0.002 mm. At one end of the pin it was a 0.001 mm slip fit, in the middle it was line to line, and 3/4 of the way along it the pin was a 0.001 mm press fit. It isn't often I come across a set of parts with good enough form and roughness that I can clearly demonstrate what all three of those fits feel like.
 

ronwild

Plastic
Joined
Sep 21, 2021
Mitutoyo micrometers are so good. I use the 293-821-30 I would swear by it. It is pretty similar to the 293-130-10 digitmatic other than it doesnt measure to a tenth of a micron.

These micrometers are insane. i'm curious what your measuring for this amount of precision?
 

texasmci

Plastic
Joined
Oct 2, 2021
Ive used them before measuring some parts that had a .0002" tolerance on part length. very repeatable.
I talked with the people who calibrate our standards, the micrometers stated accuracy was better than the labs supermic.
I had them locked up for "special" jobs due to thier cost.
 

Halcohead

Stainless
Joined
Apr 10, 2005
Location
Bay Area, Ca
I missed this thread when it was first posted, but I've got some thoughts after using one of these high accuracy mics for ~2yrs, (primarily to measure grade 5 bearing balls 5/32" and below):

1. It was annoyingly difficult to find the rated measuring force of this mic. For a unit with this resolution, hertzian deflections can be a very large factor in the measurement error, so not knowing the measuring forcecan be a dealbreaker.

2. They don't document the anvil material for the micrometer anywhere. It certainly looks like steel anvils, but some people claim they can see a seam where carbide is brazed in. I don't buy it, but either way for a $1600 micrometer I shouldn't have to debate people about appearances to figure out the anvil material. See point 1 about hertzian contact stress: carbide vs steel anvils have very different hertzian contact deflections under the same load, so this is another annoying potential source of error. (Also, why couldn't they be bothered to put carbide anvils on a $1600 mic?)

3. Repeatability and accuracy seem very good, but I wouldn't use this to try to measure 25mm +/- 0.2um, even though in theory it can (of course using it as a comparative tool w/ a good set of calibrated gage blocks is another story, and this is primarily how I use it).

4. Usability is low; it's a standard .025"/rev screw, and it doesn't fit the hand anything like a normal mic. Of course the thermal cover is essentially required if you're doing handheld measurements, and really the right way to use this is as others described, on a mic stand (and in a temp controlled room).

I used this mic to lap a 3/8" shaft to a +/- 20uin tolerance. The lapping was a pain, but the mic made it pretty easy to identify taper and hourglass form errors as I worked. I assume a nice indicating mic would do this similarly, or better. The chamfered anvils were nice in this case because they made it easy to measure shorter sections of the shaft at a time.

I assumed the chamfered anvils were to make it easier to hold the necessarily very tight flatness and perpendicularity tolerances for the anvils. But maybe there are other reasons (maybe off-axis measuring force causes the screw to tip a bit which is an error source?). Either way, they're nice in some instances, and other times (like measuring near a shoulder), they're infuriating.

It's the only game in town for 0.1um resolution micrometers, and I'd rather have one than not if I'm working on a well-funded project that needs a mic with submicron resolution. However my guess is there are indicating micrometers which achieve the similar functionality for less $. Personally I'd choose the indicating mic for my toolbox, and for a company job I'd probably want both.
 

Conrad Hoffman

Titanium
Joined
May 10, 2009
Location
Canandaigua, NY, USA
Just checked the website and they do specify carbide anvils, the diameter and the measuring force. Took all of ten seconds. That said, I suspect very few people have the knowledge to get full benefit from these. At almost $1700, I'll never know!
 








 
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