Odd Ball Thread

Cobra

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Apr 24, 2013
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I am using the collets and closer nut from a Dremel for a project.
Measuring the thread shows larger than 1/4 inch at 0.2756 which would make it 7mm.
The odd thing is that there is no matching metric pitch. The pitch is a perfect match for 40 tpi.
Anyone know, is this just an odd thread that Dremel uses or some standard thread?
Thanks
Jim
 
Several years ago I fabricated a Dremel mount that threaded over the nose of the housing. I also adapted (by drilling & tapping) an HF slot cutter arbor (originally meant for use in a router with a ½" arbor) to thread onto to the spindle of the Dremel.
This photo shows both of these "in place".
kHPIM1326.jpg
The tap I used for the housing thread was ¾"-10 TPI. I don't recall where I bought it, but the brand name on it appears to be "Bath".
The tap I used for the spindle was 9/32-40. Bought some crappy ones somewhere, and good ones from VME.
I've read elsewhere (including the Alisam's website) that the housing nose might be a different pitch. Worth checking before you buy a tap. But both of these worked perfectly for the Dremel 400 XPR I was working with. And AFAIK, Dremel accessories are interchangeable between models. So I'd think the 10 TPI pitch is correct for all.
 
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