Morse taper slipping

Do ya'll use anything on morse tapers to prevent slipping? Sure, they're not supposed to slip but my M2 tailstock does slip if I get a bit too eager with a drill bit in the chuck. I have used powdered rosin in the past and it works for a while but eventuall builds up, causing more problems. Lathe is a 40 year old Sheldon

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In my experience, the only morse tapers that I've seen that slip are ones that are moderately nicked or scored. You might consider reading the tapered surface to determine where it fits properly, and where it doesn't.

It could be that the socket is badly worn or moderately stretched, and a new male taper won't seat properly in it. If a new male taper fits the socket properly, it would be easiest to replace the MT arbor that the chuck is mounted to.

You could examine the condition of the socket, and if it's in poor condition, it should probably be reamed or carefully cleaned up using curved face stones. If it's in good condition, you can concentrate on the male taper. I'd start by making sure it's not too long, and if it is, I'd remove a small amount of the small end (either lengthwise or reducing the diameter only at the very end).

If the length is good, I'd probably put a slightly dull polished finish on the taper then firmly seat and unseat the taper several times (without rotating it), to get a reading of where the taper match is taking place. From the reading, you would be able to determine where to gradually reduce the size of the male taper in small increments, taking more readings as you proceed.

WB ..............

Reply to
Wild Bill

I have a South Bend 13" circa 1915 - MT3 tailstock taper. I ran a reamer into it shortly after I obtained the lathe (it was a bit of a mess) and it has never slipped. Things to check; Clean - no oil, no rust no nothing. No dings - either in the socket or on the tool - if it has slipped numerous times chances are there is some damage - clean this up with a MT2 reamer - very carefully - removing the very minimum required. It is real easy to remove too much. Emory tape will clean up the drill taper. Accuracy of tapers - again the tool and the socket - run a few lines of layout dye axially on the drill taper and gently run it into the docket and give it a twist. This will show up any inaccuracies. When inserting your drill taper into the socket do it with passion! MT tapers are 'self locking' and will withstand lots of torque if clean, accurate and in good condition. Hope this helps. Ken.

Reply to
Ken Davey

:-) My 50+ year old Sheldon has a little of that - I find a good ram fit with the hand does it mostly. Also - I swab it out with a cloth or paper get the oil out. Make sure the oil is off the taper (both sides). I had one that was just touching the screw - the tang was a bit long. Nominal fix did that one. Another, short in length really does good - a new Morse - precision one. So I think my male tapers are getting worn and fit in deeper and bottom out or such. One I see a shinny ring showing it is the tight fit region.

Might want to clean and test - might have to check for a 'pill' or a rub out lump of metal that builds up and does a jog to the side unlocking the taper.

That is all I can think. Hate to think of reaming - but maybe a light final reamer.


Reply to
Martin H. Eastburn

As others have suggested, get a new, clean MT2 arbor, mark it with lipstick or a sharpie pen, and test the tailstock socket for dings or lumps. If found then gently apply a MT2 reamer.

All the above is with the understanding that it is not a hardened ram in the tailstock.


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Reply to
jim rozen

All the things the other posters said need to be checked, usually there's something wrong on the mating surfaces if things slip. The Morse is a self-locking taper. One of the old-timer's dodges is to draw three or four stripes using regular blackboard chalk on the shank lengthwise. This does work, I've used it on drill chuck arbors as well as MT-shank drills. The socket still has to be clean and dry, though. Not sure if it's the chalk or the binder that does the trick, I think rosin is one component of the binder. The chalk would absorb a certain amount of oil, too.

They sell MT socket cleaners, the ones I've seen have been like a plastic reamer. Enco is one source.


Reply to
Stan Schaefer

A way to take the load off the taper is to put a protruding cross pin in the arbor just behind the chuck that can fit in a slot milled in the bottom face of the tailstock ram. Mine is a MT2 also and I used a 3/16 drill rod pin that fits in a 1/4" slot milled in the ram. The taper seats before the pin bottoms in the slot. Of course, you now have the torque load transferred to the key that keeps the ram from rotating in the tailstock.


Reply to
Randal O'Brian

Hi Sheldon --

This is the reason why Morse Taper shanks have a tang on their end, which is gripped by a receptacle to prevents slipping (turning). See:

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Tapers without this tang are incapable of transferring any significant amount of torque unless they are driven together with so much force that they essentially weld in place.

If you examine your tailstock carefully, you should find it has a rectangular cavity at the end to the taper that prevents the tang from turning.

Are you sure that you are using a Morse Taper tailstock chuck having a complete Morse Taper shank? (Some of the Cheaper imports omit it to save money at the cost of performance.)

Headstocks are a different situation, and the shaft is threaded on the outside to provide torque to chucks, faceplates, etc. The taper on the inside of the headstock is not designed to transmit torque. This is why collets, etc. employ drawbars that in addition to holding and tightening the collet, supply the needed torque.

Harry C.

Reply to
Harry Conover

Only if they get scored, worn or have a burr in them. Buy or borrow a finish MT ream and clean it up. If its in good condition it should hold and no rosin would be needed, just keep it clean and dry. Visit my website:

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expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.

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