Thread: Self ejecting tailstock problem

I would hazard a guess and say that your centre is too short on the taper.

Try a different centre or jacobs chuck.

Anything with a longer morse taper.

Tim

Hi Again,
I found one of mine must have been short, so whoever, Drilled & Tapped a Thread & put a 1/4in. Screw in it, to make it longer. Or I suppose you could weld a small piece onto it.

and Tim- the taper being short seems to be a fair guess but oddly enough, all of my centres are too short. They are Carbatec and Hafco centres. Do you have any suggestions as to where I can get longer ones?

Issatree- Welding a screw sounds good but I'd be afraid of messing up the thread at the join. Would a floating piece of bar do the trick? Is there any reason why this wouldn't work?

Not all tailstock quills are the same. I guess I should not be surprised that manufacturers haven't gotten together to establish standard lengths, but, that would be too co-operative. I have used the wrench from my routers to pry them out, and have used the wrench with a wood ship between the wrench and the tailstock shaft while cranking it in to do the same thing.

robo hippy

Originally Posted by bookend

I have just bought a tough lathe and the tailstock centres won't self eject.

I pulled the tailstock apart and the quill is hollow but threaded to accept a threaded rod that turns with the handwheel.

Is there anything missing from this picture that should eject the centre?

If the quill is threaded all the way, or threaded and bored oversize, you could get a piece of allthread and put a 3 inch knob on the outside end to force the centers out. Bevel the inside end of the allthread so that it doesn't mushroom and be hard to remove

My Hegner quill is hollow and my Oneway center body comes up to the tailstock body and comes out when the quill is backed out. Another live center is made so that it is pulled apart when I do the same. I have a 1/2 inch rod salvaged from a Xerox machine as a knock out bar for that and the drill chuck, which is mounted on a Jacobs taper on the drill side and 2 Morse taper to the tailstock.

G'day bookend!
You don't actually say which brand of live centre(s) you have but as they are from CT and H&F they are more than likely be of Asian origin who are renowned for saving material in manufacture, so I agree with and Tim that the Morse tapers are likely to be too short.

All the remedies suggested are reasonable or you can source good quality centres like Vicmarc or Sorby.

I think a short bit of rod just sitting in the quill to make up the shortfall is the easiest option. You could remove it when you don't need it, by attaching a little ceramic magnet to a rod you could poke down the hole.
Ted

Ted- The magnet idea was something I was playing around with when I suggested the floating bar and in the short term seems the simplest idea. I have a couple of rare earth magnets floating around.

As many of you have suggested, the morse taper on the live centre is too short as I tried my jacobs chuck (as Tim suggested early in this thread ) and it does self eject. Now I just need to ensure that I get hold of some lengthier centres.

There are some creative ideas here.

Thanks to all.

How about drilling and tapping a thread into the end of the centre?

Then inserting a very short bolt?

Might need a bit of trial and error.

Better than messing about with loose bits of steel and magnets.

Cheers

Tim

Life is too short to muck around, buy a better quality centers...
Jim

Woodfast have good quality centres I have been using them for 40 years, give them a call and ask if they could measure one and you can compare it with the one on your chuck

Woodfast Machinery Co. (Aust.) Pty. Ltd. -

Just cut a short length of pipe (PVC / alum / GI whatever works) with an internal dia a little larger than the quill dia in half to slip over your tailstock quill between the offending live centre and the tailstock body. Then retract the quill to eject the centre. May also pay to keep the morse tapers very clean and free from debris to prevent binding in the taper. The collar distributes the ejection forces so the centre is ejected horizontally rather than on a slight angle when only a small slip is used.

That one would most likely not work for me. I would have to remember to put the ring on BEFORE I insert the quill. That is a lot to remember most days.......

robo hippy