Morse Taper Slipping between Drill Chuck and Tailstock

[extropic]

It's my understanding that the tang on a Morse taper shank is intended for ejection only and not intended as an anti-rotation feature. That may seem counterintuitive and I can't site any authoritative publication(s) but, it's what I've read and come to believe. In other words, a properly mating Morse taper will successfully resist the torque requirement of the tool.

Regarding your lathe, If you cut the tang off, will your tailstock still eject the shortened shank?

I suspect that either (or both) your tailstock taper or tool shank taper are damaged and not mating properly.
Any ding on the tool shank causes a raised area (around the ding) that will interfere with proper mating.
Both tapers should be kept clean because the slightest sliver or chip will prevent proper mating.
Once a tool shank has been spun in the taper, the source of the problem is imprinted on both parts and needs to be eliminated.

I keep a Morse taper finish reamer to touch-up my tailstock spindle, should it ever become necessary.
I also keep a good quality (vintage unused Jacobs) tool shank to use as a Master Reference for checking the tailstock taper.
Mating the two (with Prussian Blue) verifies, to my satisfaction, that the tailstock spindle taper is inn good shape.
I also keep a cylindrical OD x Morse taper ID adapter as a Master Reference for checking (with Prussian blue) tool shanks.
Mating the adapter (with Prussian blue) with the master reference shank verifies the adapter.

If there are high spots/rings on a tool shank, they must be stoned off. Don't be concerned about any remaining low areas.
Small low areas will not significantly reduce the contact area.
Just cut down the high spots until you get a satisfactory print with the Id Master.

 

[erikmannie]

Thank you for all of the very helpful responses.

I understand that a proper Morse taper is, by itself, able to successfully prevent rotation. I also see that a tang works very nicely to facilitate ejection. So it is a fact that a tang is not designed to help prevent rotation?

Do some tailstock quills have a female slot for a tang? If so, is this a benefit in any way?

 

[erikmannie]

Are any of you guys willing to recount stories of how you had slippage while drilling and then managed to solve the problem? The slippage is very annoying.

Sometimes my drill gets stuck in the work. I believe that this is caused by too high of a feed rate. Am I the only person that has had to remove the work from the lathe, chuck it up in the bench vice and get the drill out with vice grips? That is not a good way to go if you want to maintain concentricity.

 

[extropic]

Are any of you guys willing to recount stories of how you had slippage while drilling and then managed to solve the problem? The slippage is very annoying.

Sometimes my drill gets stuck in the work. I believe that this is caused by too high of a feed rate. Am I the only person that has had to remove the work from the lathe, chuck it up in the bench vice and get the drill out with vice grips? That is not a good way to go if you want to maintain concentricity.

If you collect the bits and follow the procedure that I described in reply #11, I'm sure the Morse taper fit will be cured.

Remove the work from the chuck? Not so far.
Why not just back-off the tailstock and use a wrench on the tang to back the drill out.

So far, to me, your approach to eliminate the slippage seems scattered and non-systematic.
I think you need to take a more systematic approach.
You can't get to the bottom of the problem with a scarred tapers.
I'm sure yours are damaged (based on the problems that you've described).
After you get your tapers in good shape, we can go on to other possible factors such as material, workpiece dimensions, drill condition, drill point geometry, lubricant/coolant, feeds and speeds, etc.

 

[ErichKeane]

On my old lathe, I picked up a MT reamer and re-reamed the taper, but that is because it was pretty rough. That and clean, correctly tapered tools got rid of my slipping.

 

[Dabbler]

Just a couple of ideas to supplement what is already written above.

--Using a MT2 - even with a taper tang drill - I would never ever go bigger that about 1/2 or 9/16 of an inch. There is an upper limit on what a Morse taper (on a lathe) can hold. If it breaks free, your taper and tool are both going to get damaged. I limit my MT3 drills to .750 - yew they will even sell you a mt2 taper tang drill that is bigger than 9/16, but I'll never use one. I just learned you can buy a 1" drill in MT1 -eek-!

-- always clean your taper -with your finger - and wipe your male taper, again with you bare hands, before mating anything in the tailstock. I have lost count of how many damaged tail stocks I have seen due to crud in the taper when seating a tool in the taper.

-- it is quite possible that your male mt2 is incorrectly ground. The only remedy (unless you have rotary grinding facilities) is to replace it with a properly ground one. Here's a hint on how to be sure: buy your self a MT2 drill bit. The use the bluing or magic marker on it to check your tailstock. If that passes, then the tail stock can be used to check your taper on the tool you want to insert.

-- lastly do you insert your tool very quickly? I mean 'jamming' the tool into the taper so it seats properly?

If you take my advice on the mt2 drill to check your tailstock, here's one for comparison shopping. remember buy a REPUTABLE one, not an offshore knockoff. I've even had a tiny number of MT3 drills made in the USA not being spec - but it is very rare!

https://www.mscdirect.com/product/details/01520246

 

[Lo-Fi]

I run a ~13/16" drill in my Myford with an MT2 tailstock just fine with no more than a sharp push to seat it. I rarely drill more than a small pilot to clear the webbs, so load it up heavily every time I use it. Not once have I had it slip. As previously said: the tang is only for ejection, not to stop rotation. Morse tapers were designed at very specific angles to lock well when seated correctly, while still being removable without excessive force.

I suspect you're probably right that the taper on your drill is not correct. I've only ever had trouble with new tools or damaged old ones. Lots of new budget stuff seems to have "that'll do" baked into it, sadly.

 

[Lo-Fi]

I run a ~13/16" drill in my Myford with an MT2 tailstock just fine with no more than a sharp push to seat it. I rarely drill more than a small pilot to clear the webbs, so load it up heavily every time I use it. Not once have I had it slip. As previously said: the tang is only for ejection, not to stop rotation. Morse tapers were designed at very specific angles to lock well when seated correctly, while still being removable without excessive force.

I suspect you're probably right that the taper on your drill is not correct. I've only ever had trouble with new tools or damaged old ones. Lots of new budget stuff seems to have "that'll do" baked into it, sadly.

 

[Janderso]

Interesting, I assumed all mt had tangs. I know my mt4 tail stock does.
What’s the limit on an mt4?
1” on a mt1? Eeeech.

 

[Tozguy]

Maybe check what KBC is selling to get an idea of the practical limitations in drill size of each MT?