Special ER Collets

ER collets have always seemed to me to be a very versatile system and I'm surprised some enterprising manufacturer hasn't come up with special collets.

Two which I would find useful:

- collets with a shortened grip length (longer rear counterbore) so that short screws could be held for end-finishing after cutting from a longer screw. I know there are other ways but they get progressively more fiddly as the diameter gets smaller.

- collets with a recess on the face that would hole thin round parts - washers etc - for facing or boring.

I don't see any particular difficulty in doing these and perhaps other specials. In fact I've made the second one myself a couple of times using carbide toos on a standard collet.

Peter,

Given that the ER gets its extended range by being slit from both ends ... I would have thought that any such modification might lead to distortion of the collet under clamping loads.

That said: I'm delighted to hear that you have had some success.

MichaelG.

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

I have made Delrin ER40 collets, and for special collets , I just made them from P20 tool steel, and slit them with a slitting saw on a mandrel to stop it collapsing in on the saw.

Neil

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

Half inch square ER32 would be handy if it's doable?!

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

Should be able to hold that in an 18mm collet by the corners

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

JasonB

Could you explain elephant's foot to me. Never heard that term in the shop.

Thanks,

John

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

.... but with the added disadvantage that, if you've concentrated mostly on the ER system and your 5C gear is minimal, then you need a considerable outlay to go that route.

Michael Walters wrote:

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.

What I was thinking of more was that, with decent tooling, specials such as these could be modified from existing collets. In that case I wouldn't think it would be a significantly different undertaking than, say, the ER collet blocks.

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.

True, but you could say that of almost any tool (or many other things) that we use. They all have their limitations; we all push them a bit beyond those limitations in a pinch; thus doing, we find out what the absolute limitation is in our own situation and we gain experience.

That's not knocking what you said too much i hope,

Not at all - fair comment. And on-topic

(I do wish this editor would let us intersperse quotes with comments properly. Sometimes it really is the best way.)

More often used when talking about DTIs, basically its a flat "foot" on teh end of a shaft. As the usual 5C end stops are about 8mm dia they would not support a large flat washer so fit a "foot" to the end and you have something to push the washer against.

.... but with the added disadvantage that, if you've concentrated mostly on the ER system and your 5C gear is minimal, then you need a considerable outlay to go that route.

The ER system is really a tool holding system and its model engineers with there usual deep pockets that have taken to using it as a work holding system. The are other advantages of having two collet systems, for example if you have gone for an all ER system and are holding say a 10mm dia bar in your ER block on the mill and want to use a 10mm shank cutter on that work how are you going to hold it? A second set of ER collets maybe

Edited By JasonB on 04/04/2016 07:45:33

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

Another option is a simple split bush. Below is a collet from my router on the right which is very similar to an ER type collet and on the left a 1/2" to 8mm reducer which only has one of the slots cut all the way through, just slips into a 1/2" collet. Good for 23,000rpm and quite deep cuts so should be OK for a drill bit or small item of work

Edited By JasonB on 04/04/2016 12:30:46

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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.

For gripping short ends you can put another short end at the rear.

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This ^^^ is true

The Jacobs rubberflex collet chuck was supplied with rubber bungs for putting in the tail end for just this purpose