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I have a Frankfort Arsenal 6' nondigital that I've had about 15 years. I think I paid $29 for it. It is very smooth and accurate. I also have a HF 4" digital that I'm not very happy with. I was an automotive machinist for many years and have a bunch of different mics with a Chineese set of 1"/4" mics that measure to .0001 that are very good mics and were cheap 30+ years ago. Just under $100 for the set with standards. The one HF digital caliper soured me on digitals.
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All of our measuring tools had to go thru gage and lay out be certified and a cert number sticker applied to be used in the tool room this was part of our iso certification. Micrometers, calipers ( Vernier, dial and digitals). indicators. This was a very complete check of accuracy. This was so if one plant made a part for another it would fit. Mitutoyo mikes and digital calipers were well regaurded as were federal B&S Starret and lufkin. Indicators were mostly intrepids federals and B&S.
I have 6" and 12" digital Mitutoyo calipers and digital mikes to 2". the mikes read to .00005.
For home use a mike and standard or caliper and standard is fine and your go to. In industry everything has to measure the same part the same. Checking measuring tools to a standard before use is a must. For accurate measuring there are many ways to get the results. A height gage indicator and small granite plate set to size with gage blocks can be very accurate and quick for repetitive measurements.
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I noticed a problem in my shop lately when measuring parts. For some reason things weren't coming out just right, so I checked all of my dial calipers by closing them to zero. Yep, right on! So, what the heck is happening?
Beg, borrow or buy a 1" micrometer STANDARD. This is nothing more than a short length of polished steel, with the ends lapped down to within a millionth of exactly one inch, as set by the Bureau of Standards. Any machine shop supply company should have them. Always use the standard and any instruments at room temperature, 70* or so.
Open your "accurate" dial caliper to a little over an inch, insert the standard between the jaws and close them gently. Out of my three calipers, TWO were off by over one thousandth, but they "zeroed" just dandy. Even my trusty Brown and Sharpe was off and only the Japanese caliper reads correctly. It's wear on the rack teeth that does it, or an instrument that's low quality to begin with. If you use your caliper and mikes on a regular basis, you should do this quick check every six months or so.