boring head in tailstock for setover taper turning?

There are bell shaped center drills, but my concern is your boring head is likely to rotate in the tailstock taper a tad and then your workpiece is gonna catch, come loose and then go flying across the room.

What you need is a taper turning attachment or a tracer lathe.

I've only been doing it for a bit over twenty years, but I have yet to encounter a problem

Dale

I think it's a good idea.

S>There are bell shaped center drills, but my concern is your boring head is

I would tend to agree, but one must remember that a drill chuck arbor has a tang. Not all MT shanks have tangs.

Grant may be able to find a MT boring head arbor but it will probably have a thread for a draw bar as it is meant to be used in a mill. Something to look out for.

Regards,

Robin

The problem is the rotational play in the ram of the tailstock, which might shift the workpiece just enough to cause it to grab the cutting tool. I've not seen one with no rotational play -- it is typically a fairly loose key and keyway just intended to keep the ram from spinning. If you lock it down firmly before cutting, it might work well, but I would suggest rotating it the same direction as the spindle is turning to take out the slack before locking it down, just in case.

Good Luck, DoN.

It is possible to make a plug which will screw into the arbor, and make a tang on it. Loctite it into the shank.

But as I mentioned in another followup in this thread, I think that while it is unlikely that the MT shank will slip in the Tailstock ram, the tailstock ram has a certain amount of rotational play because of the loose (or worn) fit of the key in the ram's keyway. With a large offset, it won't take much slip to cause the depth of cut to change.

Thinking a bit more about it, I would suggest that if the offset is towards the front of the lathe (tailstock end of the workpiece smaller than headstock end), the cutting forces will tend to turn the ram CCW (lift the front), while if you are cutting with the offset towards the back of the lathe (tailstock end larger than headstock end), the cutting forces will tend to rotate the ram CW, so before locking the tailstock RAM, rotate it by hand in the direction of rotation (offset center lifted. This will take out the most likely movement.

Good Luck, DoN.

No, they're available in both tang and drawbar, at least the 7/8-20 threaded ones which is what I'd need. And yes, I'd certainly lock the tailstock quill. My tailstock is in excellent condition and locked is very rigid considering my lathe shipped out of South Bend in 1949.

GWE

"I'm thinking of turning something which has a longer taper than my compound can travel. This leads me to tailstock setover. I am considering mounting a 2" boring head on a MT shank so I can put it in my tailstock "

Seems to me that your tailstock already has that feature. Offsetting the tailstock would be way more rigid.

Hey Grant,

Not an original idea, but I've never done it either, at least the boring head part. Don't know about the "ball". That sounds unique! It's necessary to have the slide of the boring head moving in the same plane and parallel to the cross and compound slides, or the taper won't be correct. I've always wondered how you get the boring head established tightly while perfectly "level", and with the slack of the key/keyway in the tail-stock ram taken out at the same time. Maybe it doesn't matter??

Take care.

Brian Laws>I'm thinking of turning something which has a longer taper than my

Does your tailstock not have an adjustable base? If you want to use a ball center, use a ball center, but the right way to offset is to adjust the tailstock offset at the base of the tailstock, IMHO.

Mind you, with a curvy center drill, there's no real basis for the ball over the 60 degree center, either. I'm forgetting the correct term, but it's the style of center drill which makes a somewhat bell-mouthed hole, specifically to allow this to work nicely.

Greetings Grant, If you can't get enough set over with the adjustment at the tailstock then the boring head will work just fine. It will be less rigid, but with the long piece the setup will already be that way and you will be turning at the appropriate speed. Just remember to turn the tailstock spindle in the direction of the load before you lock it. Then, all the cutting forces will just tend to make it fit tighter against the key in tailstock. Cheers, Eric

And also make sure the criterion head dont come unscrewed from cutting forces.

Keeping the tool tip dead on center with this arrangement will be problematic if a tanged MT shank is used.

A consideration is whether the tang would leave it in the proper orientation. My 12x24" Clausing requires the tang to be horizontal so it will drop into the slot in the socket.

No matter *what* orientation your tang must be, what are the odds that the head will have its ways horizontal when the tang is aligned properly.

If you get the threaded style, and make your own screw-in and LocTite tang, you have the opportunity to make sure that the orientation is what you need. (The alternative might be to use some shim stock of the right thickness to keep the shank from bottoming as it screws into the boring head.

Good Luck, DoN.

Agreed -- and it is not that hard to get it set on center again when you are done. To get pretty close, there should be a pair of lines scribed in the tailstock and the base to tell you when you are quite close at least.

Good Luck, DoN.

snipped-for-privacy@d-and-d.com (DoN. Nichols)

Yes. You can make a ball center for the TS. One way would be to cut down an old MT-shank drill, and adapt or form a ball point on it. Use a dial indicator to set the ts over, and use the DI with a test bar to re-establish the alignment with the headstock. The line-up marks on the ts are ballpark, but that's about it--and too hard to see. Frank Morrison

What I use for reestablishing the tailstock to on-center is a Blake Co-Ax indicator in the headstock (in a collet) turning in backgear, lowest belt speed. It makes it really easy to see when you have it right. Without that, I would use a runout indicator with a flex or hinged shank in the collet, but that is more of a pain to read.

Enjoy, DoN.