How to use direct collets?

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cidrontmg:
I bought some M2 taper direct collets to use in my mill. They would save quite a lot of vertical space, which is always at a premium, small mill (Quantum BF 16 Vario). Problem: how do I hold the collet (and cutter) when tightening (or loosening) the drawbar? I also have some tools with an M2 shank (a dovetail cutter, for instance), with exactly the same problem.

The collet extends below the quill almost exactly 5 mm when it´s tightened (as in the picture). There are 3 equispaced cuts in the collet, 1.5 mm wide when not tightened. I´ve put a bit of 1 mm spring steel into the cut, and worn a thick glove, to be able to use the collet at all. But that´s too complicated. There must be some sort of a tool for this. How does it look like?

BTW. The obvious solution would be to drill a hole to the collet, and use a bar. Except the collets are hardened. And in the 12 mm collet, which would need the most torque to tighten, the wall thickness is just 3 mm at its thickest point. And, a hole would introduce imbalance, and that´s exactly what I don´t want... :scratch:
:wave:

Bluechip:
Not quite sure what the other end of the draw-bar is, but

The arrangement seems to be like the one I had on my first Myford ML7T
I tried a long hex headed bolt to draw the collets in, but it didn't work. Bit like yours maybe?

Then, on advice from someone who knew of these things, replaced the bolt with a draw-bar screwed 3/8" BSW at the collet end, and a sleeve nut threaded 3/8" BSCy, (26 tpi), at the other. This nipped up straight away. No need to hold the cutter at all. Never came out un-heralded as it were.

Not Myford collets, Crawford IIRC. Was 2MT.

Not sure why it should be any better, but it was.

Dave BC

Edit

Just remembered ... did give the collet/cutter a light tap with a small lead hammer to seat it, after that they stay in while the nut is nipped up.?

Tried that ? You should be able to hold the doins with the spindle flats then.

Not sure whether this has any relevance whatsoever .. :scratch: Zebedee calls

John Hill:
Can you 'wring' the collet into place? That might hold it while you screw the draw bar in and tighten it, to get it out loosen the draw bar then give the head of the draw bar a bit of a tap to loosen the collet.

Thats how I manage tapers on my lathe anyway.

Bogstandard:
You should be able to spin the drawbar down into the collet by hand until it starts to grip in the spindle. If it doesn't check below.

Take out your drawbar and make sure that the collets screw onto it very easily. If they don't, run a tap down the collet threads until they do. Be careful though, MT fittings can have a choice of two different threads, some are metric, some imperial. Either M10 or 3/8" Whitworth, both very close to each other in pitch/tpi.

A friend had the same sort of problem, and he found he could easily recut the threads in the collets from Imperial to metric with no ill effect on the grip. That choice would have to be yours.

It might be that the threads on the end of your drawbar are just too long for the collets, in that case just make up a collar that sits under the drawbar head, say 3/4" long.

Been in this situation with my old mill, but in MT3, I ended up with two drawbars (two different threads) AND a collar just for the sake of it.

Bogs

cidrontmg:
That´s what I have now.

The collet set has 3/8 x 24tpi (UNF) threads, I made a drawbar for them, the rightmost one.
The extra collet has a 3/8 x 16 tpi (BSW) thread, the drawbar for it is in the middle. That drawbar also works with lots of other tools acquired from England, of course.
The original drawbar is M10 x 1 (fine) thread, on the left. It fits most of my stuff, drill chuck, ER25 collet chuck, etc.
Don´t you just love standardization...
All the threads are very easy fits in their resp. tools, "tuned" with split dies.
There´s also two brass washers in the middle drawbar, to adjust the length of any of them. I can fix any tool I have, easily, securely, but without unnecessary force - except the collets. I just can´t hold the collet tight with only 5 mm protruding from the quill, without doing awkward contortions.
I´ve been thinking about something like the tools used to extract oil filters, but in miniature. The collets are 18 mm dia. at the end, and of course, slightly tapered (M2). So there´s not much for the band to grip on. But such a tool would have also the advantage that it would close the collet around the cutter, and prevent it from falling down when it is being tightened. Something like this.

That is for diameters from 50 mm up, so maybe not usable with 18 mm... But the idea seems worth experimenting. Is there something like that, but small, ready-made, or should I cobble one up myself?

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