Jacobs chuck problem

[martin baker]

Hi, I need so advice on this one, I have noticed on a jacobs chuck I bought second hand ,that its not running true, is there a way to correct this problem, thanks, Martin.

[Russell Neyman]

What do you mean by "not running true"...? Not aligning with the live end? Do the bits wobble? Is the morse taper not seating properly? Is this occurring when you mount it in the live end, free end, or both? And, how is it mounted onto the taper?

[martin baker]

The chuck & morse taper is a one piece unit, & my problem is a wobble , so with drilling on the lathe my boring s are off center.

[Russell Neyman]

Well, if you've eliminated dirt or a wood chip inside the taper opening, that pretty much narrows it down to being bent or dented. And that might explain why the previous owner decided to sell it. I've seen machinists re-work the morse faces by reverse-mounting the chuck and running a file over it.

[Greg Just]

not sure how much you have invested in the chuck, but I would recommend taking it to a machine shop and having them check it out. However, it might cost more than it is worth.

[martin baker]

Thanks for the info, looks like I will have to replace it & count my loses!

[martin baker]

​Thanks, I was fearing that.

[Russell Neyman]

Can't you use it on the free end of your lathe, statically, and let the motor turn the wood? In that arrangement it should give acceptable results for hogging out a starter hold, and it can't wobble. Besides, the tailstock usually has a little play in it, so you can align it and tighten it down.

[martin baker]

Gota tell you guys what I have done today! this morning after reading your feedback I thought I would check it out a bit deeper, so I released the morse taper from the chuck body, mounted the morse taper in the head stock , there I could see the "wobble" so I thought I would turn down the stub end by lining up a square "t" rest to that taper & with a carbide bit holder that I have made out of a piece of gas pipe ,carefully reduced the stub taper( I think its called the "J" taper) until the "wobble" disappeared, now I am a happy man again, I do so hate to throw tooling away, & love it when I can , fix or improvise with stuff from the "junk"? box. Just a end note, if anyone out there would like to see the carbide tip turning chisel I will gladly add a image, I was given some carbide bars years ago & have been experimenting with different grind angles etc, & I am very pleased with the results in finish & ease of use. Thanks again for the feedback . I am a new boy but already fell I am among friends. All the best, Martin.

[Russell Neyman]

Gota tell you guys what I have done today! this morning after reading your feedback I thought I would check it out a bit deeper, so I released the morse taper from the chuck body, mounted the morse taper in the head stock..... Thanks again for the feedback . I am a new boy but already fell I am among friends. All the best, Martin.

Glad that worked out, Martin. When you said the chuck and taper were a single unit, I was skeptical but didn't want to argue. Lesson here is never give up! Good luck.