I know the feeling, I always double check the readings on my cheapies, funny how my two Mitutoyos always give perfect measurements, and they are nearly 30 years old.

Dunno if they've improved, but the early dial calipers in the 70s sometimes skipped teeth and gave false readings, and I've never trusted 'em since.

I've got a cheapy Aldi or Lidl digital that sometimes jumps 200 thou for reasons best known to I don't know whom – I use it for rough or dirty work –  but my M&W value line one is good enough to its half-thou resolution.

For double-checking I've got a Mitutoyo mic that I bought new in 1976. Originally it also had a mechanical digital counter reading to 0,01mm, but that jammed after a month or two so I took it out. Its Imperial vernier mic still works within a tenth or so – I checked it with slip gauges today.

Edited By Mick B1 on 12/08/2019 21:43:42

How is the vernier implemented on the dial caliper?

Change the battery (Ok I know I should call it a cell).

Mitutoyo are fantastic calipers but beware of fakes. They are extremely good copies and hard to distinguish from the real thing unless you know what to look for. Plastic case, paperwork, every thing looks right, but it's not. Buy only from a reputable dealer to be sure.

If you are doing precision work you must use a micrometer, a caliper is not a repeatable tool for precision work in my book.

Regards plasma

Moral: Don't look a gift horse in the mouth…

Neil

The inaccuracy of the callipers may just be an adjustment issue , on the side next to the little locking knob there are two tiny screws that adjust the jaw tension so maybe giving these a tweak will sort the problem out . I adjusted mine so they just start to cause some drag but still operate smoothly . After that clean the inside surfaces of the jaws by lightly clamping some clean paper ( i use printer paper) between the jaws and pull it through then close the jaws and hold it up to a light source and look at where the jaws meet there should be no light shining through – if there is repeat the cleaning process and if it doesn’t improve they are stuffed so only good as a scriber or checking approximate sizes only .

As nobody's mentioned technique yet, I'll mention it takes practice to get accuracy out of calipers. Straightforward enough to get to within 0.05mm with a digital caliper but care is needed to exceed that. The amount of pressure applied to the thumb wheel should be consistently correct as should the angle of the jaws to the work. Although digital calipers display to 0.01mm, they are rarely more accurate than ±0.02mm – don't be surprised if the digits bounce about!

Cheaper calipers can be less smooth in operation which makes them harder to use. Some people are better than others at getting consistent results. When accuracy is needed micrometers are best. And even though they have a stiffer frame and a ratchet eliminates most human error, they too need practice.

Dave