Accuracy of Digital calipers

[redneckalbertan]

According to their catalogs, some can be used in inspection and record the readings in a computer. That just seems to be a big investment for an inherent "imprecise tool"..To be very candid, I love my dial and vernier calipers and would like for anyone to dispel negative feelings that have been raised about them.

The data recording feature of the calipers does not denote precision in QC work. I would see that feature as a boost to production, it would eliminate the time it takes to manually enter the information and reduce the risk of an error made by the QC personal entering the wrong number. Not everything requires the precision of aerospace components, but still needs QC controls and records in place.

[georgepapa]

hi Mr Ron,
to my opinion the only difference, regardless of how many decimlals the digital has, is not accuracy but readability of the result, particularly now that I am 74....
regards,
george

[pete]

FWIW, unless things have very recently changed with Starett's digital caliper design, then the Mitutoyo's are recognised by almost everyone over on the PM site as vastly superior over the Starrett's the last time the question about digital calipers was raised. Starrett's caliper's take a specialised and expensive battery, and there internal circuitry design is more than poor compared to the Mit's according to a lot of people who seem to know what there talking about. I bought a set of Mit. solar powered, and if I was looking for another digital caliper I'd certainly buy the exact same thing again. Yes there a bit expensive, and there really expensive against the cheap Chinese battery powered digitals. But they are the best set of calipers I've ever had my hands on. I've also got a set of 6" & 12" Mit. dials, and the digitals are way nicer than them for feel, and I think due to that there accuracy is better. But you can split the measurement on the dials if the needle is between divisions. Checking multiple parts that have the same dimensions might allow you enough repeatability with calipers to do that. (maybe)

Many here do know how to properly measure with caliper's, but for those that don't yet. The thumb wheel on most calipers is only for quick movement's. To get the best accuracy caliper's are meant to have the fixed and movable jaw squeezed either between your thumb and fingers for the smaller measurements, or lightly between both hands for the larger measurements. And like any other piece of quality measuring equipment, a light, consistent, and experienced feel is required to get the best and most repeatable accuracy. You'd be surprised just how many very experienced people don't know that. But compared to a decent micrometer, then yeah even good brand name caliper's aren't that accurate. But they do have there place. For me they would be the most used tool in my shop so I bought good one's, and the price of those makes me NOT stack tools on top of them, or leave them where they could get covered in chips. I dropped my 12" Mit dials just once and the repair cost's were 60% of a new set. And the only Mitutoyo repair location in Canaduh is over 3,000 klms away. So I'm real careful now how I treat any precision tools.

There is of course an easy way to double check both your own abilities and your caliper's average accuracy if you own a set of gauge blocks. Just randomly pull 5-10 blocks out, arrange them in different combinations of sizes, DON'T look at the sizes before measuring them, and write your measurements down. Then just check what you measured against what the blocks actually are.

Pete

[Charles Spencer]

It's been over 35 years since I last worked in a shop. I obviously didn't use digital calipers then. I did however have a 4" brass and wood caliper that I carried in my breast pocket. It was 100% accurate at telling me if that screw was 3/8" or the stock was 3/16" x 1 1/8". I find that my cheap HF calipers also perform that function, probably even better.

Of course back then I also had micrometers as I do today. They will tell me if a part is 0.753"

Charles

[tornitore45]

I have a metric dial caliper made of plastic, made in Switzerland, it resolves 0.1 mm
Bought in 1974, has been used through my work to size electronic components.
Plenty good for layout or winding transformers, even tiny ones.
The advantage is that nobody would steal a green, plastic, metric caliper.