Are you chasing threads, or making new fasteners? Sizes, etc? Calipers are not a close tolerance measurement tool. If it has to be "on", then you will need a micrometer. Depending on how I angle, twist, alter pressure, etc., I can see differences approximately .005" with my digital calipers on the same item. Probably could get more with some persuasion! This is not to say you need to run out now and buy a new set of mics! You might be fine with what you have.
minime said:Wareagle wrote
Again, thanks for your advice, I don't generally have fine tolerances to worry about, I'm only repairing/ making new parts for my and other peoples toy steam engines.
Eg, currently I'm making a small wide topped screw, out of brass, to blank off an existing BA3 threaded collar in a toy steam boiler (14psi type). The threading doesn't seem to be going well, even though I've changed the OD of the brass a few .0001 each time. I'm now wondering if its the cheap set of BA taps & dies I bought, lack of tolerance in my cutting or the threads of the die I'm using blocking up. I do use a cutting/threading compound, but the thread on the last two I tried to make, simply got chewed up each time.
I have a high quality 3BA die on order, but an wondering if it's me or the cheap die.
Cheers
Chris
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