Tailstock Quill Hardness Question

I've searched this forum and google for information on how hard in Rockwell Hardness Number a tailstock quill generally is and can't find a thing. Do any of you guys know or know where I can get the information? The lathe is a 14 X 40 Rockwell model 25-210.

I'm trying to determine what type of insert to use to cleanup a 3MT in a hardened quill prior to finish grinding. Besides the quill being hard the DOC will be only a few thousandth at a pass and I know most inserts perform better when the minimum DOC is taken. Which is generally much more than a couple thousandths.

I'm guessing 0.010" to 0.015" needs to come off before finish grinding and the quill nose will probably need to be cut back.

I have already tried cleaning it up with a new HSS finish reamer but the reamer wouldn't touch it.

Why do you want to remove that much material? All that is needed is restore the angles and surface finish. A low spot that does not clean up is no problem. If it is not in horrible shape then .002-.003 should give you a 90% clean up easily, probably much better.

I'd just dress the high spots. Wrap a strip of emery cloth around a round straight dowel (piece of drill rod or something straight), and carefully 'file' lengthwise with it, feeling for those spots where it wants to catch in order to reduce the bumps. Have a new trial shank handy that you can blue up and slide in to twist a little to see how the contact is coming along.

I'd probably take an old drill or something with a decent shank or turn up a new 3MT and then mill a few flat spots lengthwise, leaving a few lines of contact with the 3MT and put some abrasive compound in there and lap the taper a little. Test for fit. Don't worry about scores and dings that make the thing ugly, they're going to happen again anyways. Even the rattling around that occurs as you slide a taper into a socket is enough to ding it now and then, hard or not it seems.

tdmidget said:

Why do you want to remove that much material? All that is needed is restore the angles and surface finish. A low spot that does not clean up is no problem. If it is not in horrible shape then .002-.003 should give you a 90% clean up easily, probably much better.

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You may be right about the amount of metal to be removed to get it reasonably clean. However there are some nasty gouges that look .010" to .015" deep and that's what I was thinking of when I first posted.

Good idea with the lap, I think I'll try it with one of my old 3MT drill bits or maybe an adapter I have.

Thanks

nc5a said:

However there are some nasty gouges that look .010" to .015" deep and that's what I was thinking of when I first posted.

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Wouldn't matter if they were through holes as far as accuracy goes. So long as no raised burr is left at their margins, [1] nor debris allowed to accumulate enough to fill them anyway.

Would justify extra attention to cleanliness so they don't camouflage a chip and perhaps lead to sumthin' jamming in the taper, so yeah, full-cleanup is not a BAD idea.

[1] The burrs on my AB5/S 5MT were indeed at azures. the knockout most of all, but the locking-wedge cutout as well. A former Sov Block 5 MT reamer (Moldova or Ukraine, IIRC) was hard enough to clean those up, thankfully.

With the amount you're thinking about taking off your tools are going to seat waaay further in the socket than before, to the point that they may simply not seat, unless you take off a considerable amount on the face, then you have the ejector to think of...

.010" out of the bore will put you almost a quarter inch deeper.

In the past I've just bellied up and gotten a 3mt reamer, turn it carefully, couple of turns and all the burrs and crap are gone. To remove any material past that you'd need bigger arms than I have or be really motivated. The bore might still look ugly compared to fresh ground but it will be darn true to its original condition.

Also put wood dowell in the chuck and push into the reamer and turn with a end wrench that fits the reamer. This way any misalignment of the centerlines is void. A little pressure and i mean a little with sme cutting fluid on the reamer and a couple of turns should do the rick and as others have said if you have 5% deep scores, that will be ok to leave. Merry Christmas. Rich

Get a quality 3MT shank and coat one small part of it with abrasive compound. But not the kind with carbide particles, otherwise they will be hard to remove. Maybe never. Then insert into taper with straight in and out strokes on an high spots. Now all high spots are taken down.

If the same shank is still in good condition then insert straight side into the headstock with a collet. Slide tailstock into shank with a little compound and turn the headstock hand wheel.

If you don't use collets then a point inserted into a chuck will center the shank as it is being turned. The shank blanks I have all have a center point.

(This is not a off the wall idea, did this myself some years ago after some discussions)

Screwmachine said:

then you have the ejector to think of...

.010" out of the bore will put you almost a quarter inch deeper.

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This MATTERS. A LOT. That's why a simpler de-burr is the usual go-to.

Otherwise? One can "accidentally" if not by intent, wander into the non-trivial exercise of making a new quill. From "scratch".

Not rocket insemination. We probably all know how to do that. Or can learn fast enough if we must.

But if one can avoid the expense, time and distraction from other needfuls...