As both of those uses are work holding then emergency 5C collets would be a good option with the added bonus that they hold at the business end as Michael mentions. The washers can already be done in a 5C with an elephants foot extension to a backstop.

All these specials would mean a large outlay for any supplier if they were to be in all the increments of the popular ER ranges, could quite easily run into 100 stock items which would have a limited turnover.

I do think there would be a market for emergenct ER collets as ER1-40 would only meanhaving to stock six products which the purchaser could then make to exactly their screw, washer, tool, etc. size as most people don't want to set up to get the angles and cut the slots.

J

It may be worth talking to JWA Tooling

**LINK**

MichaelG.

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Edit: This is going off-topic, I'm afraid, but

have a look this mad and rather pricey collet nut !

Edited By Michael Gilligan on 03/04/2016 20:14:25

Well I could imagine that would work on some materials and at high spindle speeds and if someone wants to spend that much then its up to them. A moulded plastic fan with a bore to suit normal ER nuts and then just pushed on, would do the same job.

You could buy a 3D printer, print a fan and have lots of money left over!

Then again you could do the job properly and print it using 3D laser sintering…..

Ian P

Expensive nut! They do collets in 1/2mm steps (which could be handy) but at $27 each they can keep them.

I think they don't exist commercially speaking, for precisely the reasons you gave, those uses are far too specialist for it to make any kind of money in the volume you'd need to sell. I would add further that they probably do exist but only when commissioned to do so.

The latter collet could be quite troublesome if you were tempted to use a longer piece of rod or take too big a bite as the grip range would be too small, even with ER collets as they are they can slip occasionally.

That's not knocking what you said too much i hope, i do like to hear new ideas people have, i just hope too much criticism doesn't put people off putting their head above the pulpit.

Michael W

MG mentioned quite correctly, that as ER collets are slit at both ends they are unsuitable for gripping items that only touch the very front of the collet.

However it one had a particular requirement (and only had ER and not 5C) that justified making a one-off collet then a custom ER collet could be made that was only slit at the front.

It might not have the optimum taper angles or closing system but I cannot see why it would not work.

Ian P

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Quite correct, Ian

I was thinking along those lines whilst we were out this morning [domestic chores].

It would, of course, remove the 'extended range' … but that should not be too much hardship on a 'special'.

MichaelG.

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This ^^^ is true

I don't understand why there is a belief that you can't use ER collets for short work-pieces. I frequently do that with no problems. The design of the collets, with slots from both front and rear, ensures that the bore remains parallel as it closes down. There should be no need to put another short end in the rear.

Russell.

My 7-6mm ER32 collet has a larger diameter for the back half of its bore as do all the smaller ones in my set. This does not cause these collets to grip out of parallel. This implies that it would cause no problem to hold anything with just half the length of any ER32 collet's bore.

Martin