Thread: Metrology for Amateurs

Hi Stuart,

Screenshot-dti test.xls - LibreOffice Calc.png

Interesting reversal there.... is that hysteresis? or something else?

Regards
Ray

Hi Ray,
Thanks for that
I really couldnt say where the errors are coming from.
The zero point is only about 0.001" of travel from the rest point. maybe thats not enough?
The compac does seem to have some hysteresis when you are moving the master. Hard to say and I dont think a video would show it. Though the numbers show its repeatable within 0.00002" so maybe I'm making it up.
My normal "Stuarts theory of measurements" would say the master was out.....not so sure about that.

Must run, time to pick up some pretties(I hope).

Stuart

This is an affordable micron caliper. Unmistakably made in China. Resolution is 0.001mm. Retails for around $180. If this was well made, this could not only replace a conventional micrometer, it would be a FAR more versatile tool in an amateur shop, since it can measure internal, external and depth to 0.001mm.
Micron Digital Calipers

This seems to be the same brand, US$118.50 each
Micron Digital Caliper - China Digital Calipers,High precision

For comparison, this is a "real" micron caliper made by the Swiss Sylvac. This sells around the $1,000 mark. Clearly not an option for the amateur.
http://www.sylvac.ch/doc/print_vm_cat_4_en-GB.pdf

I just wonder, has someone already tried a Chinese micron class caliper? Is it really repeatable? It does not appear to have carbide jaws, nor a constant measuring force device. But at $118 this is really dirt cheap.

Chris


PS: there is one in here too, among an incredible choice of different special purpose calipers:
http://www.f-m-s.dk/CalipersPDF.pdf

Originally Posted by Stustoys

They were checked against a master height gauge graduated in 0.00001"(not to be confused with calibrated).

G'day Stu.

If you get a chance, can you please post a picture or two of your master height gauge? I'm interested in how you are reading that 5th decimal place. Does that have a dial in tenths, and a vernier on that again?

Regards Phil.

Originally Posted by cba_melbourne

I just wonder, has someone already tried a Chinese micron class caliper? Is it really repeatable?

G'day Chris.

Surely that's just a marketing ploy. So what if they have tweaked the resolution up to give them a third decimal place. By their own admission, the accuracy is plus / minus 0.009 mm, in the range 100 through 150 mm. 18 microns of permitted error, on an instrument that displays to one. That third decimal, may as well be a random number generator, on those cheap models.

Meaning the ability of being about to display down to one micron is nearly redundant. Smoothing and rounding on a two decimal display, surely is just as accurate?

I'm thinking there's a reason the Japanese aren't offering them. You have really expensive highly refined examples like the Sylvac. And then there's knock off copies.

I'd bet mechanics measuring disk brake wear are gonna love them though.

Regards Phil.

(A P.S to your P.S)

PS: there is one in here too, among an incredible choice of different special purpose calipers:

Be careful of dropping links to that Danish Company here. The owner of that company is a notorious windbag and spammer, on several other forums. Don't be surprised if he google's him self and ends up here flagging his gums.

Agree with Phil, the whole mechanics of calipers is such that they will never repeat accurately to that resolution anyway. Nothing more than a gimmick in my opinion.

Pete

Originally Posted by cba_melbourne

This is an affordable micron caliper. Unmistakably made in China. Resolution is 0.001mm. Retails for around $180. If this was well made, this could not only replace a conventional micrometer, it would be a FAR more versatile tool in an amateur shop, since it can measure internal, external and depth to 0.001mm.
Micron Digital Calipers

This seems to be the same brand, US$118.50 each
Micron Digital Caliper - China Digital Calipers,High precision

For comparison, this is a "real" micron caliper made by the Swiss Sylvac. This sells around the $1,000 mark. Clearly not an option for the amateur.
http://www.sylvac.ch/doc/print_vm_cat_4_en-GB.pdf

I just wonder, has someone already tried a Chinese micron class caliper? Is it really repeatable? It does not appear to have carbide jaws, nor a constant measuring force device. But at $118 this is really dirt cheap.

Chris


PS: there is one in here too, among an incredible choice of different special purpose calipers:
http://www.f-m-s.dk/CalipersPDF.pdf

I really don't know why they would make a Digital caliper with a resolution of 0.001mm, they would flex more than that and the sliding head is not a precision fit on the bar. 0.001mm is micrometer territory where the tool is rigid enough to hold that sort of accuracy.

I doubt the accuracy in my 0.01mm digital calipers because of the way they are made, though you can usually rely on the 0.1mm in the reading.
For comparing readings of something where you hold the caliper the same way to measure each part I will use the 0.01mm reading and always think of it as +/- 0.02-0.03 mm.
If I am looking to get withing 0.01-2 etc mm exactly I will get the micrometers out.

Dave

Originally Posted by Stustoys

Well we know what Marco thinks about a micron.

I know what he thinks about 5 microns. What he thinks about one is probably not fit for a family timeslot.

For those of us trying to follow along at home, I found this old document from Mahr which describes indicator errors:

http://docs-europe.electrocomponents...6b800314b3.pdf

Originally Posted by Machtool

Does that have a dial in tenths, and a vernier on that again?

Hi Phil,

Yes,
I'll snap some pictures in a minute.(wish BT was here so they wont look like rubbish)

Originally Posted by Bryan

What he thinks about one is probably not fit for a family timeslot.

Possibly not, but its likely to be pretty damn funny.

Stuart

These 48 pages are worth printing out:
http://www.gagesite.com/documents/Me...easurement.PDF

Much more of the "same" metrology know-how can be found here:
http://www.gagesite.com/metrology-tool-c-1153-l-en.html

(Sorry if the link had been posted before, I just found it and can't stop reading....) Chris

Originally Posted by cba_melbourne

This is an affordable micron caliper. Unmistakably made in China. Resolution is 0.001mm. Retails for around $180. If this was well made, this could not only replace a conventional micrometer, it would be a FAR more versatile tool in an amateur shop, since it can measure internal, external and depth to 0.001mm.
Micron Digital Calipers

This seems to be the same brand, US$118.50 each
Micron Digital Caliper - China Digital Calipers,High precision

I have a set of Anyi digital calipers, just the normal 0.01 resolution. The quality is pretty good, at least as good as the MarCal, and up there with Mitutoyo, hardened lapped sliding parts, and smooth operation. Long battery life ( never needs to be turned off). I think micron resolultion is ridiculous, might as well be a random number (as Phil suggested) but the quality of the calipers themselves is pretty good.

Regards
Ray

Here you go

Originally Posted by RayG

I have a set of Anyi digital calipers, just the normal 0.01 resolution. The quality is pretty good, at least as good as the MarCal, and up there with Mitutoyo, hardened lapped sliding parts, and smooth operation. Long battery life ( never needs to be turned off). I think micron resolultion is ridiculous, might as well be a random number (as Phil suggested) but the quality of the calipers themselves is pretty good.

Regards
Ray

Thanks Ray I was considering buying a set of Anyi caliper