Looks like R8, but won't seat properly in BP mill

[G-ManBart]

I bought a lot of drill chucks at a local machinery auction to get a couple that I wanted to keep with plans to sell the others. Luckily, the two I'm keeping are fine and fit perfectly in my 2J 2hp Bridgeport, but two I plan to sell don't seat properly. I can tighten the draw bar all the way and the chuck is still hanging maybe a quarter of an inch low and hasn't seated. I tried two drawbars and got the same result. Then I measured the shank on the two that are loose and found that they're 1.235" at the widest point where the chucks that seat properly are 1.250".

Is there a shank size that looks similar to R8 but slightly smaller? Could it be a draw bar issue (I think both of mine are the same)?

I'm not out anything either way and I can always sell just the chucks....one is an Albrecht and the other a U.S. made Jacobs 14N, but it's a bit confusing to a newbie like me. Here's a pic of the two that won't seat next to an R8 Albrecht (far right) that does seat properly.

 

[markba633csi]

I do seem to remember there is one type of shank like you describe, but I can't recall which mfg. used it- Cincinnati? Gorton?
The clue is the missing collar at the drawbar end- most R8 stuff has it but those don't
-M

 

[Ulma Doctor]

the smaller diameter tooling should suck up higher into the spindle.
you may be bottoming out inside the collet threads
you can test the theory by stacking a couple washers under the drawbar's hex, and trying to insert the collet again
it may take a couple times to get it right