Joined: 10/21/2009
Posts: 6
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I have an air gage for inspecting close tolerance bores and the gage tips cost anywhere from $250.00 to $400.00 each. I want to make my own gage tips and I looked at the gage manufacturer's web site for dimensional data. They call for a .44-20 UNF thread. I looked for data on for that thread and found nothing I also looked for a tap and couldn't find that either. I measured the mating part (male) the O.D. is Ø.310 and the threads are around .025" apart wich would make it 40 TPI. and there is a 5/16-40 thread. I could single point the thread to fit but I would rather tap it. Has anyone heard of a .44-20 UNF thread?
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Joined: 11/3/2009
Posts: 3
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Sounds to me that this is just a proprietary thread so the you have to buy their parts. Go ahead and single point your own to 5/16-40 and you should be good to go. I can't imagine what the .44 refers to if the mating thread is .310 od. You should be able to find a 5/16-40 UNS tap somewhere
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