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Stuck Morse Taper in headstock

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Bodger7

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Hi
I have got a jammed/stuck morse taper drive centre in my lathe headstock and would be grateful for any suggestions for freeing it. I have tried knocking it out with the knock out bar but without success and I have hit it fairly hard. I have used stilsons on the drive centre and can rotate the drive centre clockwise but very slowly and using a lot of force. However, this has not loosened the drive centre and using the knock out bar at the same time as rotating the drive centre is not achieving anything.
Any suggestions or is this a job for an engineering workshop?
 

CHJ

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Sounds like the taper has rotated in the spindle and galled the metal surfaces.

What lathe do you have, is it reasonably easy to remove the spindle.
Someone with a fly or hydraulic press may be able to push it out after suitably supporting the spindle.

How substantial is your knock out bar is it the maximum diameter of the headstock bore? a thinner bar may be springing and absorbing some of the shock load.
The trouble with hitting the knock out bar too hard whilst the spindle is held in its bearings is that you are side loading the bearings which may not do them a lot of good. Be prepared to change the bearings if they show signs of play or rattle after hitting the taper out.
 

finneyb

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Never tried this - but I wonder if a hammer drill on the end of the knock out bar would be any use, taking it slowly

Brian
 

Dalboy

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Something I have done on stuck parts similar to this is take two hammers hold one tight against the side of the drive centre and tap the opposite side. After a few taps try the knock out bar again
 

Bodger7

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What lathe do you have, is it reasonably easy to remove the spindle.
My lathe is a Wivamac. I have read the instructions for removing the spindle and, to me, they do not seem entirely accurate. Most of the steps to move the spindle are fairly straightforward but removing the pulley from the spindle is causing me problems that I am about to try and overcome.

I suspect that the problem has been caused by the drive centre as I have not had problems with other MT fittings.

Thank you to Delboy and finnyb for their suggestions. I have started to try and remove the spindle now so will persevere with that at the moment but if that fails I will try your suggestions.
 

Robbo3

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When my AT1628VS was new I didn't clean out the head stock as thoroughly as required & the drive centre stuck. It didn't matter how hard I hit the supplied knock out bar, the centre wouldn't budge.
I tried a mallet, then a 2 1/2 lb lump hammer. I had visions of the ball on the end of the knockout bar shattering but it stood up to all the forces that I applied.
In the end I couldn't get enough swing, so pulled the lathe out from the wall then hit the knock out bar with all the force that I could muster & the drive flew out, hit the tailstock & flattened the centre point.
Other than that no damage occurred
 

Simon_M

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Avoiding damage to the head bearings is very important. A slow turning force is preferable to a frustrated quick well intentioned blow with a hammer.

Could you grind way some of the morse taper to get “purchase” on it and then use an impact driver to rotate/free it in direction of rotation (in reverse) with headstock locked (not using the indexing pins)?

Or make a “flat” drill a hole and use a peg/wedge to pull it way (like removing the chuck from a pillar drill)? Many problems with dealing with hardened steel in a situation like this, although hardened steel is very resistant to galling.

And/or use a threaded bar/nut/washer and spanner to exert a force e.g. against a wall (spread the load) to push it out slowly instead of the knockout bar?
 

Trevanion

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I’d try heating up the spindle then blasting the centre with freeze spray, then quickly try knocking it out.
 

Bodger7

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I have now managed to remove the spindle from the headstock. The problem with the pulley was that there were two grub screws in one of the threaded holes and having removed one I had assumed that that was the only one. Examination with a torch showed another one in the same hole.
I tried a couple of engineering workshops without success but eventually found one near Dover that was prepared to have a go at removing the drive centre. The spindle has now been detached from the bearings but all efforts to remove the drive centre failed. Heat and heavy blows from increasingly large hammers had no effect whatsoever and I have now left it to be bored out on a lathe and a new MT made. The engineer doing the work couldn't believe how tight it was.
Thank you for all your suggestions but I suspect that it was always going to end up in an engineering workshop. However, the suggestions made will be filed away for future use if the problem arises again.
 

Inspector

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Bummer. While it is apart write down the numbers from the bearings so you can order them should the old ones start making noise if you haven't already decided to replace them. If it has a belt then sizing the old one too for a spare would be a good idea before it lets go. These problems never seem to be a one and only if you don't have spares.

Pete
 

Simon_M

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If the belt is captive (between bearings) then it’s worthwhile to inspect and/or change it whilst you can. If the morsel taper is MT2 or MT3 then buying one rather than making one is a cheap/better option. Just a shame the spindle doesn’t come with an internal thread - would help in these situations.
 

Bodger7

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Thanks again for all the helpful suggestions but I reckon that the only one to work would have been the exploding hammer!!
 

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