I have a Jet mini lathe that has a jammed live center stuck in the quill. Reversing the hand wheel is no use. I have tried to place a flat bar between the head of the live center and the quill, only to have the head come loose on the shaft. I also tried using a knock out bar inserted in the hole in the hand wheel and tap the center out with no luck. Does anyone have another solution to freeing the live center?
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Stuck live center
- Thread starter Rich L.
- Start date
Are you unable to retract the quill until the live center self-ejects, as indicated in the Owner's Manual (Fixed or Variable Speed--see section on Removing and Installing Live Center)?
If no other option, a tapered shaft can often be loosened by applying force perpendicular to--rather than along the axis. Some sideways taps with a non-marring object might loosen that live center for you.
The last option that comes to mind would be chilling (freezing) the Live Center shaft while heating the quill, combined with one of the above methods.
If no other option, a tapered shaft can often be loosened by applying force perpendicular to--rather than along the axis. Some sideways taps with a non-marring object might loosen that live center for you.
The last option that comes to mind would be chilling (freezing) the Live Center shaft while heating the quill, combined with one of the above methods.
Rich
I have had some trouble with centers that had short shafts not ejecting. But in those cases the knockout works fine.
But you have to retract the quil all the way, then use the knockout
I have had some trouble with centers that had short shafts not ejecting. But in those cases the knockout works fine.
But you have to retract the quil all the way, then use the knockout
Hi Rich,
I had a stuck spur drive on my lathe. My method, although crude, worked. I used a pipe wrench to get mine to turn. Once it turned, it came right out. Also by suggestion from another forum member I soaked it with WD-40.
Hope this helps!
I had a stuck spur drive on my lathe. My method, although crude, worked. I used a pipe wrench to get mine to turn. Once it turned, it came right out. Also by suggestion from another forum member I soaked it with WD-40.
Hope this helps!
Tap???
It might help to get angry when you "tap" with the knockout bar or a drift punch, and use some vocabulary your mother didn't teach you.
I bought a Black & Decker hammer drill at a garage sale. It uses Morse taper bits. Really, Morse taper in a hammer drill. 😱 I reckon the bit had been stuck for several years. Normal Morse taper release is by a wedge in a slot in the MT body. It eventually succumbed similar to the above treatment.
The WD-40 is a good suggestion, but a pipe wrench won't work on a live center unless it's no longer live.
It might help to get angry when you "tap" with the knockout bar or a drift punch, and use some vocabulary your mother didn't teach you.
I bought a Black & Decker hammer drill at a garage sale. It uses Morse taper bits. Really, Morse taper in a hammer drill. 😱 I reckon the bit had been stuck for several years. Normal Morse taper release is by a wedge in a slot in the MT body. It eventually succumbed similar to the above treatment.
The WD-40 is a good suggestion, but a pipe wrench won't work on a live center unless it's no longer live.
john lucas
AAW Forum Expert
A good penetrating oil is better than WD-40. However the suggestion to use the knock out bar and hit it hard is good as well as the twisting. Either method is good and bad. Hitting it too hard could damage the bearings although one good rap that may release it is better than a bunch of half hearted raps that just beat up the bearing. The twisting motion can scratch the morse taper surface however if it's rusted in it's already got pit marks. I'd go with the rap and penetrating oil and if that doesn't work then try twisting, and if that doesn't work have a friend twist while you hit. Do give the penetrating oil a chance to soak in. I've been able to release almost anything with enough patience and a good oil.
Joe: Good point! I kind of missed the live part. 😀 I wonder if a small air hammer would be effective applied to the back of the live center or the knock-out rod?
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Oh my! I'm covering my ears -- or my eyes. If the spindle socket wasn't trashed before, it will be trash after using a pipe wrench.
That is good advice, Joe. What is needed are very forceful "manly" man whacks and not "girlie" taps.
Twisting it out is never good. If you hit the back of the taper with a forceful enough impulse to release it, then almost none of the energy will be absorbed by the bearings. Anything less than sufficient impulse to separate the parts and practically all of the energy is absorbed by the bearings. If you are really concerned about damaging the bearings, then remove the spindle from the lathe before knocking out the stuck taper.
The important thing about an impulse is that it needs to be very high speed -- as fast as you are able to hit the stuck taper with the knockout bar. Slow speed taps spread the energy out over too long a period of time to be effective.
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He seems, from title through discussion to be talking about a live center, Bill. That is normally on the other end, with no bearings but its own, and that is also a moot point by his post.
Grip with the pipe wrench and rap the handle. Toss the live center if it's one of the shorties that don't self-eject.
ruined my first PSI pen mandrel when it stuck in the Jet 1220 and I then compounded the problem when in frustration I used the knockout and then got it stuck to the pen mandrel and neither of them would move! finally got the mandrel to move by striking downward with a deadblow hammer, then pipe wrenched the knockout and mandrel apart.
Learned my lesson, I clean everything before i insert centers and spurs now.
Learned my lesson, I clean everything before i insert centers and spurs now.
Stuck Live Centers
I used to have the problem of stuck centers in the tail stock and learned from a lathe manufacturer what caused it.
The tail stock is cut to #2 MT specified tolerances set by industry standards as well as setting the depth that the automatic eject has when you screw the tail stock all the way back in to eject the center. The problem is that a lot of center manufacturers don't follow those industry standards, and make their centers too short so they won't automatically eject.
Then you complicate things a bit when that center is drilled through, because a knockout bar goes right through it.
I've gotten my stuck centers out by using a thin wrench used for bikes between the center and the tail stock housing and popping it out.
Then after I learned what caused it to begin with I either cut a dowel plug, or threaded the center from the back and put a bolt in - in order to make it long enough for the tail stock auto eject feature to work.
I haven't had a stuck center since.
I used to have the problem of stuck centers in the tail stock and learned from a lathe manufacturer what caused it.
The tail stock is cut to #2 MT specified tolerances set by industry standards as well as setting the depth that the automatic eject has when you screw the tail stock all the way back in to eject the center. The problem is that a lot of center manufacturers don't follow those industry standards, and make their centers too short so they won't automatically eject.
Then you complicate things a bit when that center is drilled through, because a knockout bar goes right through it.
I've gotten my stuck centers out by using a thin wrench used for bikes between the center and the tail stock housing and popping it out.
Then after I learned what caused it to begin with I either cut a dowel plug, or threaded the center from the back and put a bolt in - in order to make it long enough for the tail stock auto eject feature to work.
I haven't had a stuck center since.
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A knockout rod can be angled a bit so that it does not go through the hole. First crank the quill out as far as it will extend. This will enable you to get the knockout rod more solidly onto the shoulder of the back end of the live center.
Rich L
Did you get your live center unstuck and if so what method did you use?
Did you get your live center unstuck and if so what method did you use?
The Last Resort...
This has happened to me before, and I had to resort to what will hopefully be a last resort. Try this last.
I had gotten a live center stuck in the tail of my Jet Mini. It was a hollow center, and too short to work with the auto eject. I usually just angled the rod to knock it out, but I couldn't get enough contact to deliver a good blow. I used the method of putting a piece of metal between the center and the quill, only to have the entire head come off. At that point I had a tube stuck in a tube, and I was not about to try to twist it in the taper. Finally a light bulb went off and reminded me that it's easier to pull in a straight line than it is to push.
So, here's what I did... I drilled and tapped the center, and inserted a long bolt. I then stuck the bolt behind the jaws of my chuck just like a woodworm screw. Lightly tapping, vertically, on the bolt while retracting the quill brought it right out. I'm not sure about the design of your center, but I think mine is still repairable.
This has happened to me before, and I had to resort to what will hopefully be a last resort. Try this last.
I had gotten a live center stuck in the tail of my Jet Mini. It was a hollow center, and too short to work with the auto eject. I usually just angled the rod to knock it out, but I couldn't get enough contact to deliver a good blow. I used the method of putting a piece of metal between the center and the quill, only to have the entire head come off. At that point I had a tube stuck in a tube, and I was not about to try to twist it in the taper. Finally a light bulb went off and reminded me that it's easier to pull in a straight line than it is to push.
So, here's what I did... I drilled and tapped the center, and inserted a long bolt. I then stuck the bolt behind the jaws of my chuck just like a woodworm screw. Lightly tapping, vertically, on the bolt while retracting the quill brought it right out. I'm not sure about the design of your center, but I think mine is still repairable.
Would it be possible to run the live center out a ways, then put a block of wood or a wide piece of metal between the rim of the live center and the tailstock, then run the live center back in?
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No because it would very likely damage the bearing unless you can make certain that you only make contact with the inner race of the bearing. If you apply pressure against the outer race (which is what would happen if you inserted the piece of wood or metal between the rotating bearing housing and the tailstock quill) then it will damage the bearing races by applying a very large axial load.
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Is/has anyone read the original post? He tried the insert the wedge object and retract, and "the head came loose on the shaft." The bearings on that end no longer have a role to play.