dwhite

Help with new tailstock

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turret.jpg.4cb40062f4cf21a590a4bcfddca6102c.jpg   I just bought another Perton lathe and it came with two tailstocks.  A regular one that isn't broken (yay!  I finally got a lathe with a functioning tailstock) and this one in the picture.  I took several pictures but Apple is conspiring against me and won't let them upload so I'll start easy.  I think this is a turret tail stock from looking at pictures online. One end has a taper that looks like it would accept a collet although an 8mm collet sinks so far in that it is flush.  Could it be for a 10mm collet?  Or something else entirely?  I tried a morse taper 2 drill chuck from my wood lathe and it doesn't work on either end.  How in the world do you attach things to it?  If I can get my photos to come through I'll post more.  Also, it doesn't lock down because the button is all bent up.  I hope someone can enlighten me.  Thanks!

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OK, I got my iphone to work.  Here is a picture of the bottom of the tailstock showing the button is badly deformed.  It doesn't lock down.  Can I put it in a vise and tap the steel back into position?  Should I heat it with a torch first?  It sort of looks like a crack might be forming where the round button connects to the shaft.  Help!button.thumb.jpg.d625cc31c04d5e9ef8bfd88a9a4d208a.jpg

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More.  Here is a picture of the front bore showing what looks like a taper for a collet.  The second picture shows a standard 8mm collet in it.  It sits way too deep and would probably go even deeper if you could rig a way to tighten it up.  There isn't a pin to fit the keyway of a collet.

frontbore.jpg.2ee66e86d713b46bc1b5e90b450a4e68.jpgfrontcollet.jpg.211cff22db89075a6dc657aee7f24e20.jpg

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L ast one.  Here is a picture of the rear bore.  It has a short chamfer and, down deeper and hard to see, a ridge where the diameter decreases by a fraction of a mm.  I don't know how one goes about measuring something that deep.  Here an 8mm collet sits about right but there isn't enough material to support it.  I tried a MT2 chuck in both ends and it didn't fit as you might expect since neither taper is long enough and the taper appears wrong.  So that's my best description of this piece.  Anybody know what it is and how to use it?backbore.jpg.87f705070cbc09039d26519ba13747e2.jpgbackside.jpg.88444900ae6fe336430e8a429f2b7995.jpg

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There may only be two of those on the planet and you found them both, nice!

Its not a turret tailstock - example of a turret tailstock below.

I do think watchmakers lathes that take collets in the tailstock are somewhat rare, at least they sell for a premium.  I've a Pultra that does, buts a bit bigger, 10mm.  No idea why its seating the collet so deeply.  what are the drawbar thread particulars - dia and pitch?

A Morse taper is a self holding taper - unlike watch collets that are steep and self releasing.  The taper per foot is much less (around 5/8" irrc).  MT 2 or even 1 will look huge compared to a watchmakers lathe....there is a MT 0 but I can't see from those photos where it would go.

As for measuring the bore, there are lots of tools but the most basic is a set of small hole gauges and telescoping gauges.  These are set then measured with a micrometer.  Cost and accuracy goes up from there.  A set of small hole gauges irrc usually covers from 1/8 to 1/2"

As for the bent piece, some ham fist maybe got a little over zealous.   You could start banging around on it, but you could also wreck the fit of the rest of it easily enough.  I'd make new one out of something tough - a preheated chrome moly like 4140.   As its not holding, I'd say make one or draw it up and get it made.

MBjCgD7.jpg

 

 

 

 

 

Edited by measuretwice

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Thanks!  I called it a turret because it was the only thing with a lever that matched what I have.  Do you suppose it had a draw bar at one time?  I'm wondering if that's how it worked.  I have some casting equipment that I'm not sure still works but if it does, I could cast an insert for the back to accept a drawbar out of brass.  As far as the button, that's way above my ability to make and I don't have any way of holding stock that big.  I don't know for sure but I'm guessing a machinist would charge a young fortune to make something like that so I'll probably be going the hammer route.  I'm guessing that getting it red hot would make shaping it easier but I really know nothing about steel.  The thing, whatever it is, is really a precise machine and functions very smoothly.  It would be a shame to let it go to waste.  Think of the watches I could ruin with it!

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lol, before you take a hammer to it, carefully measure it and draw it....if hammering does scrap it, you'll have what you need to get some quotes.   I don't know what is not shown on the rest of it, presumably just a cross drilled hole for a cam?  imo its well less than an hour's work so might not be too bad to have made.

The problem with getting it red hot, is the metal has the consistency of Plasticine.  you can easily bend a 1" bar by hand for example.  So, a hammer strike might bend it downward, but it will also spread out under the hammer, as if you were hitting Plasticine.   If you can, with a small oxy acetylene torch, get a red zone as strip along the bend line, that would be ideal and bending it back easy, otherwise you may better cold forming....but be really careful not to bend the vertical column.

Also, on heating it, if its cross drilled for a cam, it may be that that part of it at least would have been heat treated (although the mushroomed bottom suggests its something less than tool steel strong).  Get the whole thing red hot and you undo the heat treating.

I would guess it was made to accept collets so would have a drawbar...no knowledge of that lathe, just probable speculation based on a tailstock quill that appears to have a self releasing tape (as in collet style) vs a Morse taper. 

Edited by measuretwice

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Thanks!  I'll try the cold approach.  If it cracks I have a neighbor that is an expert at welding small cracks in steel and he would happily do it free.  Now I have to come up with an idea for a drawbar.  I'm not very mechanically minded yet (which is why I'm having so much trouble with watches).  Since the 8mm collet didn't fit I suppose it was made for a larger size?  I've never seen a 10mm collet, do you happen to know if they are that much bigger in the face and tapered part?

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4 hours ago, measuretwice said:

I just measure a 10mm PTA, it was 15.1mm dia, large end of the cone.  Body of course is 10mm.

I'm doing some research and wondering if you know if the standard 10mm watchmakers collet is the same as the type D collet?  I see both names tossed about, sometimes in the same discussion.  Also, I found an ebay listing for a 10mm lathe with a Levin micro drilling tailpiece that functionally does the same thing as mine so that must be what it is for.  Levin makes a modern version which sells for $1800!

 

 

 

 

 

 

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My impression is "D" collets are 10mm collets, but don't go buying a set on the strength of that.  There is some info here http://www.lathes.co.uk/derbyshire/.  i'm sure I have at least one Levin 10mm collet, let me compare it to the PTA collets.

 

You could probably find a drawing of a Levin collet and see if it will fit.


With all these collets, there is no "standard" unfortunately.  Their origins date to a time when everybody did their own thing.   Now a large number are interchangeable, but not all ....there can be slight differences in the thread and length overall and even the body dia.    If you hunt about on the web are two lists of collet dimensions I remember seeing, one for European lathes and one for US lathes.  They might give some clues

 

 

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Finally found the proper name for this tailpiece.  It is a Levin 10mm collet holding tailpiece.  I got a drawbar that seems to fit exactly although I don't have a 10mm collet yet to test it.  I have one on order.  From dimensions I have found online for 10mm Levin D collets it should be long enough to engage the threads.  If not, I'll have to find a machinist to turn a bit off a shoulder on the drawbar.  Thanks everyone!

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