Has anybody made ER Collets

[rmuell01]

I have the ER25 for my Clausing Mill but I need a 3/4" collet. How would you make them?

Rob

[Greg Q]

I believe that 3/4" is outside the range of an ER25...the chart I have shows 5/8 as the maximum fractional size.

3/4" is the largest that can be held in an ER32 collet holder.

Greg

Also...the good collet suppliers get fancy money for them because they are not easy to grind accurately. There are eBay sellers in Hong Kong that sell ER collets for reasonable money. I have a couple of sets-very happy, and good value.

[PixMan]

Actually, 22mm (.8661") is the largest diameter you can hold in an ER32. For ER25, it's 16mm (.6299").

[Ian B]

ER collets have a normal published maximum capacity for each range, for instance the largest ER40 is a 26-25mm. However, you can sometimes find "oversized" collets - here's a 27-26mm ER40:

http://cgi.ebay.co.uk/ER40-collet-27...item335ef6174d

They work fine. Unfortunately, going from 0.629" to 0.750" is probably too much of a stretch. What size is the hole through the nut? At a push, I suppose you could have a collet up to the same bore size as the nut itself.

Another option would be to buy a larger size ER collet chuck (say, and ER40) and then only buy the individual collets that you need, or from 5/8" to 1". This is a nice solution anyway, as the larger size ranges tend to be very stiff when they have small bores (eg. a 2 to 3mm ER40 takes some tightening). Ball bearing nuts help a lot.

Ian

[Ian B]

From this:

http://www.rego-fix.ch/pdf/Katalog_E...-13_2004_e.pdf

it looks like the socket behind the collet is 18mm diameter for the ER25, which is smaller than the 19mm that you're after.

Ian

[rmuell01]

What I should have asked is: Has anyone made an ER Collet. Do they have to be ground? I've made 5C collets, wondering if it's the same process.

Rob

[jkilroy]

For the price I can't see any economy in making your own, unless you happen to have a fully stocked shop with ID and OD grinding and heat treat facilities and even then unless you employ CHEAP labor its got to be cheaper to buy them.

[TGTool]

If I understand the OP's problem, he has an existing system and a need to hold a workpiece that's just bigger than standard collets allow.

If you treat it like an emergency collet situation I'd say sure, it's perfectly feasible. I've not done it but the process should be to turn up a solid piece to the external dimensions of the ER-25. For short term use there's no need to even harden it, but it would be good to get the 8 degree feature fairly accurate. Then chuck that up in the collet holder and bore it out to 3/4 for some depth probably just short of full collet length. Clearance hole behind if that seemed desirable. Then bandsaw some slots from both directions and carefully remove any burrs to restore accuracy. It's a compromise and there are clear limits to what can be done such as the through hole behind, but the short answer to "can a collet be made?" is yes.

[plunger]

I have made my own collets. In Africa things are expensive and thers no harbour freight It was for a er 50 collet chuck I built. I ordered the nut and made some blank collets which I machined with the idea of finishing when The size I need comes up. Nothing fancy to it. I just used plain old mild steel.When I looked into it I needed to buy a special steel with spring properties as well as hardening properties which would be hard to do in a home shop environment. My solution was to sacrifise the clamping range considerably.( er 50 clamps in increments of 2mm I think) I made a collet to suit my needs for a specific job and if I need another specific job I just machine and drill and slit my spare blanks. . I simply Held the er collet in a vice and sliced it with a slitting saw on the mill.I also reduced the number of slots compared to the real ones. But I too would like to know how a jig for the slitting could be made because dont forget an er 50 collet is a big collet and is easy to hold in a vice Not so easy with a smaller collet.They work very accurately and I can put a straight shank er 16 collet or bigger in my er 50 collet if I want to do smaller stuff
eugene