MT removal problem - help please.

[Acanthus]

I have found a problem with the tailstock of my Axminster M950 lathe.
This has a MT2 taper, and I want to take the live centre out, so that I can fit a chuck. However I have thus far failed to shift the arbour of the live centre at all.
I have been told to use the screw advance mechanism, but when I tried this all that happened is that the point of the live point got pulled off the base of the LC leaving it and the arbour still firmly stuck in the taper.

My son suggests heating the body of the tailstock, while cooling the arbour with a stick carved from a block of frozen ice.

Any ideas on how to shift it.

David

 

[loz]

Is the tailstock not hollow to allow pushing of the live centre out from behind ?

 

[chrisbaker42]

I have the M900 which is very similar and for me it has always been a case of putting a bar in behind and tapping it with a hammer, if it still remains stuck tap a bit harder.

 

[Acanthus]

Thanks guys, but the arbour seems to be hollow. Using a rod I can just about feel an edge where the arbour ends, and the hole through the tailstock continues, but this is not large enough to hit.

David

 

[loz]

Ok, but the live centre cannot be hollow all the way, at some point it will be closed ! - just put a long screwdriver/bar/rod whatever in from the end of the tailstock and give it a whack.

 

[loz]

ps - once out - clean/ream ( with an MT reamer ) gently the MT ! before putting anything back in

 

[gus3049]

I had exactly the same problem with the Clark equivalent.

Had to take it to an engineering company in the end. They got it out all right but not without separating the various bits of the revolving centre! They heated it and hit it with a pretty big hammer apparently. It sounded horrendous from outside the machine shop.

After cleaning both inside and out and thoroughly drying it all out, the next time I tried to get it out it was jammed solid again. I gave up!

I suspect that putting too much pressure on with the tailstock didn't help but it still shouldn't do it.

Not a great help I'm afraid.

 

[CHJ]

There should be a retaining screw, or maybe it's just the quill clamping lever/stud, can't remember, but removing that and continuing to wind the quill forward and you should be able to remove it from the tailstock, once it's disengaged from the screw.

Once out of the tailstock you should find it easier to drift the centre out.

Centres are normally ejected by the rear of the centre coming up against the end of the actuating screw, some centre brands however are shorter than the morse standard and fail to eject this way, I have drilled and tapped one of mine and fitted a short large headed bolt in the rear end.

Sounds like the morse taper socket/centre has corrosion bonded together, careful cleaning with some fine abrasive on a suitable wooden taper may clean the socket up enough to avoid the expense of having to ream it out.

 

[Acanthus]

Thanks guys - I have managed to shift the pineapple. No signs of corrosion or other reason for it sticking. Will give it a bit of oil before re-fitting, then keep fingers crossed.

I now know more about morse tapers and arbours than I did yesterday

Cheers
David

 

[János]

Hello,

You should not put oil on the mating surfaces of a Morse-taper, as the whole concept of the Morse-taper is based on friction fit. The best practice is to take out the arbors from the bore of tailstock and headstock every time, you finished your daily work

By,

János

 

[Acanthus]

Thanks for that Janos. I live and learn.
So I will go and take it out again, and wipe the oil off with an organic solvent, then dry it all and take it out at the end of each session.
This site is fantastic - I have read dozens of books on lathes and woodturning, and would never have come across advice of the quality and usefulness that I have had today.

And hey I also found out that you can tap down through the jaws of a chuck and knock the arbour out! Little things, but I was only allowed to do woodwork at school. If you were doing sciences then metalwork was off limits.

Does any one know of a readable book that explains basic engineering machinery for the thick?

Again Many thanks guys

David

 

[jumps]

I believe that there is a push-out rod supplied as standard with that model for exactly this purpose - if you are missing it you might want to contact Axmister for a replacement; it's rather useful!

Alternatively just source a length of rod in an appropriate diameter.

 

[CHJ]

I believe that there is a push-out rod supplied as standard with that model for exactly this purpose - if you are missing it you might want to contact Axmister for a replacement; it's rather useful!

Alternatively just source a length of rod in an appropriate diameter.

Problem the OP was having though is that the revolving centre he has is supplied with interchangable centre bits so that a ring centre can be used for tailstock boring.
Trying to knock one of those out just results in driving the small centre out and you are left with a bore hole more or less the same size as the quill actuating screw for an auger and not enough of a lip on the rear of the centre body to engage the knock out bar.

 

[jumps]

I believe that there is a push-out rod supplied as standard with that model for exactly this purpose - if you are missing it you might want to contact Axmister for a replacement; it's rather useful!

Alternatively just source a length of rod in an appropriate diameter.

Problem the OP was having though is that the revolving centre he has is supplied with interchangable centre bits so that a ring centre can be used for tailstock boring.
Trying to knock one of those out just results in driving the small centre out and you are left with a bore hole more or less the same size as the quill actuating screw for an auger and not enough of a lip on the rear of the centre body to engage the knock out bar.

I had thought the design / sizing of the dedicated rod would cope with that - obviously not!

 

[CHJ]

I had thought the design / sizing of the dedicated rod would cope with that - obviously not!

The rod can not be a bigger diameter than the bore of the actuating screw, and this is invariably only just big enough for a standard auger.

 

[myturn]

David
Even if the arbor is bored right though there must be enough of an edge on the rear to get a drift on it. Not all lathes have a self-ejecting tailstock and the only way to remove them is with a drift. You did say you could feel an edge at the rear of the arbor.

Extending the tailstock quill to its maximum should help as the arbor would then be furthest away from the end of the threaded screw with more chance of getting the drift on the rear edge.

If that doesn't work it may be that the drift needs to be bent slightly and/or the end ground at an angle to get a good purchase on the edge.

Glad you got it out in the end