Jacob's chuck probs>>>

[follow3]

Hello All,

I recently bought some kits for bottle stoppers and decided to try my luck. The "mandrell" that was speced. for the kits is mounted in a Jacobs chuck, and the blank then turned.

Everything went well for me until it was time to part off the "tail end" and back off the tail stock. As you can immagine, the whole time I was wet sanding the acrylic blank, the chuck was working it's way out of the headstock.

My question: Is there a way to keep the Jacob's chuck from coming out of the headstock when the tail stock is not in use?

Thanks,
Steve

 

[desert1pocket]

How are you mounting the jacobs chuck in the headstock?

 

[follow3]

It has a MT 2 on it, so it just slides in.

 

[desert1pocket]

It shouldn't be coming loose like that. You should be popping the chuck in with some force to get it seated, not just slowly sliding it in there. If you can turn the chuck inside of the headstock, or pull it out by hand, you didn't get it fully seated. If seated, the only way it should come loose is with the use of a knock-out bar. You also want to keep things clean, because sometimes dust and dirt will build up inside the headstock or on the chuck, and will prevent it from properly seating.

 

[VisExp]

My jacobs chuck has a hole threaded in it on the MT2 side. I have not had occasion to use it but I think it takes 1/4 20. If yours has the same you could make a draw bar by threading a piece of all bar in there then pass that through the headstock, put a washer on and tighten it with a nut.

I've figured this out by doing some research online for draw bars. I haven't done this myself so if I'm wrong or have described the process wrong someone please feel free to correct.

 

[gwilki]

My head stock is bored through, and my the MT 2 has an internal thread. I just put a wing nut onto a long 1/4" bolt, put the bolt through the head stock, thread it into the MT 2 a couple of threads, then spin the wing nut up to the hand wheel on the head stock. I've never had the problem of my jacobs chuck coming out, but I have had my Beall spin out once or twice. This solves that.

 

[brough]

I had same problem, found my MT 2 chuck was to long on the morse taper by about 1/16 inch or so, ground off the end of taper and then it would seat in my Jet mini lathe and not be a problem.

 

[Firefyter-emt]

Yep, you need a draw bar. If it's a 1/4-20 I would suggest you make a knob from wood that has a t-nut in it and keep all spinning objects round so that it can't catch your shrit or what not.

 

[desert1pocket]

If the MT on the chuck is too long like brough's was, a draw bar will hold it in place, but it probably won't run true or centered. Just a thought.

 

[Randy_]

Steve: Not all Jacobs chuck arbors come with threaded holes for draw bars. If yours does not, the best thing to do is purchase a threaded arbor. They can be had from a number of vendors for less than $10.
Here is one source: THREADED ARBOR.

If you buy an arbor from LMS and have one of the mini/midi, you want the one with the short Morse taper. You will probably need the one that goes from #2 Morse to JT33 if your chuck is a 1/2" chuck. If the chuck is a 3/8" chuck you may need a different size JT. The correct size should be marked on the body of the chuck.

If your arbor is threaded, be sure to check the threading before you purchase hardware to make up a drawbar. The comments in this thread have all talked about 1/4" x 20 tpi threading; but I have also seen arbors threaded for 3/8" x 16 tpi threading so be sure you know which you have.

What to do in the meantime.....

If you have a good fit between the lathe spindle and the chuck arbor it probably should not come out so you might do a couple of things to be the fit it good. Stick a rag or paper towel into the spindle t be sure there is no dust or dirt interfering with the fit. it wouldn't hurt to use a little solvent to be sure there is not an excess of oil or grease in the spindle. Likewise, clean off the shaft of the arbor and run your finger over it to make sure there are no burrs or rough spots. If the arbor has any surface rust you could clean that up with some steel wool or 600 grit sand paper. When everything is as clean and smooth as you can get it, stick the chuck back into the lathe. Fully retract the chuck jaws and give the chuck a good rap with a block of wood. Don't over do the "rap" because you don't want to damage the spindle bearings.

The above may help or it may not; but I consider it only a short-term, temporary fix. Do work toward getting a drawbar set-up if you plan to use your chuck in the headstock on a regular basis.