replying to Norm Dresner, drillpress wrote:
I also have a JT 2 1/2 Chuck on a Columbia 515 drill press made in Taiwan. I
compared the taper dimensions with the published Jacobs taper dimensions and
found that it was likely consistant with a current Jacobs 6 taper. I
purchased a new Jacobs 6 chuck and it fit perfectly. I have no idea how that
conversion can be explained.

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