Out of four calipers for example:
Two Starrett 120As read .014 slightly over the line but not at .01425. One caliper is very lightly used and the other is my companion.
One import digital readout caliper says .0145, and my Mitutoyo Limited Edition almost never used says .0145.
Looks like the Starrett's are off. Didn't expect this and wonder if others see things like this.
I measured everything more than once under clean conditions. I measured the example with a guitar string.
Once the jaws close that's it. No free play. I tried a little force on the flats, not the front 30 degree bevels.
In real life, the digital indicator is never used because I didn't trust it and I don't like dealing with batteries. Although the display blinks
when the battery needs to be replaced. The Mitutoyo is almost never used as well as one of the Starretts.
My Mitutoyo 8" digital calipers are remarkably accurate, and repeat nicely. This is said within the context of calipers mind you, which are incredibly sensitive to deviations in hand-use person to person given those great, big, long jaws. I just measured a 2" ceramic gage block @ 2.00" even, a 1" block @ 1.0005, and a .650 block @ .6505.
I take care of them mind you, and I don't lend them to anyone else. I'll take digital calipers over mechanical's every day.
Having said all that, what other's have said is common wisdom, which I'm sure isn't news to you: "Precision" measurements in my shop are done with Micrometers (my Mitutoyo digital mics are great), or Indicating Micrometers (we have Mitutoyo and Etalon's), Optical Comparator, or LaserMike.
