How to set/adjust center line adapters

mickri

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The center line adapters for my caliper arrived today. They will live on an 8" vernier caliper. I put them on the jaws and then got to thinking how do you adjust these things so they take a accurate measurement. I have some thoughts on how to do that but thought it might be best to ask you guys what is the proper way to do it.

Took some measurements. Each adapter is .375 OD. When the two adapters are pushed against each other the measurement is .75 which is what I would expect. And I would expect the caliper to read .375. It doesn't. The caliper reads .383. How do I adjust out this error?
 
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I tend to agree with you John. I thought about maybe adding a shim to make it .010 off. That would be easier to remember and make the math a snap.
 
That would be a good instance to use a digital caliper where you could zero it as needed, or set it for the appropriate dimension
 
My digital caliper was an el cheapo that went through batteries in the blink of an eye. I don't use it any more. One way or another I will get this figured out. Thanks for all of your suggestions.
 
Thanks for the suggestion on a digital caliper. I will stick with my old school vernier and dial calipers for now. I have been fiddling around with the fit of the center line adapters. The error is now down to .005. I'll have another go at it later today. Then live with whatever it is.
 
May I ask where you bought the adapters, so I won't make the same mistake? Thanks.

Edit: Nevermind. I just ordered a set from Walmart. No joke, Walmart. Mitutoyo center attachments, $66 + tax. If they don’t perform up to expectations, there’s a Walmart return counter about a mile from my house.

Tom
 
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I am done trying to adjust the adapters. By carefully filing off the black coating I got the adapters down to no error. As soon as I tighten the set screws I am back to .005 error. I will live with. To be honest my skill level probably isn't good enough to drill holes within .005 anyway.
 
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