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Digital caliper accuracy?

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Just picked up a cheap digital caliper from Harbor Freight (20 $ stainless steel model). Instructions say it should be accurate to +-.001", but as far as I can see, it measures -.002 or more, not really +- .001" accuracy (yes, I zerod it). Am I expecting too much, or are other, more expensive calipers more acccurate?

Even though it's good enough for what I need, I'm exchanging it. It doesn'r look new anyway (it looks like someone else's chicken fingers were on it).

Or maybe I should spend a little more for a better one?:moon:

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My Mitsumi goes to .0001". Accuracy is also delendant on the condition of the 'jaws'.

Harbor Frieght, you get what you pay for. Yours is fine for checking wheel alignment or a bolt length.Did you zero it? You should do that on each use.

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Regardless of what the readout is capable of, accuracy depends on proper and consistent technique, also what you are measuring. You will tend to get more error trying to measure something out at the tip than in near the beam.

If you the jaws are clean and it doesn't read within the advertised accuracy of zero every time you close it I'd take it back.

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My Mitsumi goes to .0001". Accuracy is also delendant on the condition of the 'jaws'.

Harbor Frieght, you get what you pay for. Yours is fine for checking wheel alignment or a bolt length.Did you zero it? You should do that on each use.

I really really doubt that. Calipers are accurate to .001", many show the next digit but it is either 0 or 5. This is not to be trusted however.

Micrometers are accurate to .0001 however and are recommended for high accuracy.

-Engineer who uses these on a daily basis.

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A buddy of mine picked up a set of the digital 0-6" from harbor freight and we measured a bunch of gage blocks with them and a set of digital starrets and found almost no variation.

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You shouldn't be using a caliper for really percise measurements anyway. A micrometer should be used for measureing pistion diameters, valve stem diameters and such.

I have a pair of calipers but I mainly use it to measure ballpark lengths like when setting up forks. I also use it to measure the size and length of screws. If you need .002 accuracy or better, use a mic

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I use the a harbor freight digital caliper at work a lot measuring valve shims and other applications. They are quite accurate for things like that and they are cheap so if you lose it or break it, it is no big deal. For real accuracy crack out the mikes.

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I brought the caliper back and exchanged it. The replacement has the +- .001 accuracy claimed. I guess you need take them home and test them ....

I'm not using it for "machinist" type work anyway ... good enough for a commoner. :moon:

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I bought one of those cheap $20 digital calipers at Harbor freight about 4 years ago. All i`ve used it for is checking shims. It will read what is on the shim everytime, if it`s 1.75 on the shim thats what it`ll read.

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I bought a pair for around the house and they are actually pretty good. They are identical to several other brands except for color and name.

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My Mitsumi goes to .0001". Accuracy is also delendant on the condition of the 'jaws'.

Harbor Frieght, you get what you pay for. Yours is fine for checking wheel alignment or a bolt length.Did you zero it? You should do that on each use.

Mics will go to .0001"; calipers generally don't. My expensive set ($200-ish) of digital calipers I use at work are .0005".

If you have a set of gauge blocks around, you can check it with that. Make sure the calipers are clean and don't bind up or stick. I usually wipe mine down with WD40 on a lint-free cloth after i'm done with them.

Good news is that most digital calipers are very repeatable, meaning when you measure a part it'll read the same over and over. Accuracy may not be as precise as a more expensive set (One inch on yours may not be the definition of one inch). But if you're comparing two parts to see which one's thicker, the cheap ones work great.

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