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Mystery collet

JimGlass

Stainless
Joined
Jan 15, 2003
Location
Genoa, Illinois
The collet at the bottom of the picture is the mystery collet. The collet at the top of the pic is a 3C



The 3C and the mystery collet seem to have the same thread, .639 dia x 26 TPI. The Body Diameter is .688, 2.422" OAL, large diameter is .953, Keyway width is .136. The collet does not fit a 3C spindle adapter bushing. I also think the tapers are different. The mystery collet is stamped 3/32 POPST bro <Chicago>

What is this collet??? We have a bunch of them. Thanks, Jim
 
Could it be a 3AT?

Here is a chart of collet dimensions: http://www.loganact.com/tips/collet.htm

Thread size and diameter are very close, but not identical.
I agree that it is probably a 3AT. The AT stands for the brand that shall not be named and their 10 and 12 inch lathes, including the C brand, with 3MT spindles had adapters and draw bars available as options. The threads are very close to 3C, as noted.

Porst Bros. was a Chicago collet and lathe accessory maker. They existed in the 1930-1950 era, as near as I can guess.

Larry
 








 
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