ER collet chuck/mill incompatibility?

You'll get a set of 5 R8 collets for about £32, then you can put the chuck in its box and have less overhang and more daylight

You'll get a set of 5 R8 collets for about £32, then you can put the chuck in its box and have less overhang and more daylight

Thanks for the further suggestions.

Duncan, I don't think I'll often be short of daylight with this mill, but I may well end up getting a few R8 collets if I buy one to do this job.

Jason, I'm afraid I haven't got a "proper" lathe yet, only one for woodturning; one is coming as soon as I can work out where it's going to go.

If I were to buy an R8 collet or two, what options have I got for clamping the chuck shaft in the vice [or directly on the milling table] so that I can flip it exactly 180 degrees after milling a flat on one side? The arch-shaped clamps on my vee blocks aren't quite deep enough to clamp down on the chuck's shaft when it's laid in the vee groove, and I'm running low on ingenuity on how to set the job up otherwise.

What Duncan says is true and is a common admonition around here.

OTOH, having the kind of job I did today - multiple parts requiring multiple cutter/attachment changes in each setup - I think I'd have gone slowly mad. I'll stick to ER collets.

I do have sets of both ER and R8 collets. The R8 set is actually very handy as a memory test. ( ...."Now when was the last time I used an R8 collet?" )

Bill, unless I am missing something why dont you use a pair of C spanners, its what I use and its simple.

You say you have a 5mm hole in the spindle but a C spanner wont fit because its pin is too big and square, surely 5 minutes with a file on the C spanner to make it fit is the answer and dead simple.

Might be heresy on an engineering forum but a small stilson pipe wrench would work. Might scuff up the holder a bit though (could line the jaws with a bit of rubber to lessen the effect). Once the jaw width is set it should take no time to grip for both tightening and loosening.

With a suitable pin hook spanner costing less than an R8 collet let alone a carbide cutter that may cut the mustard I would say a spanner is the better bet and saves rounding off your C spanner and which you need for the collet nut anyway..

Yes. You are right. It is heresy.

Or use/buy a drill chuck for the mill and do the same naughty thing?

Thanks a lot for the further replies.

Ron, I'd have to alter the radius of my collet nut C spanner as well as its pin to make it suitable for the spindle hole. I'd then be unable to use it on the collet nut.

I'm going to follow up Jason's suggestion, and see how I get on.

Thanks again.

Jason

Sorry I don't know why I attributed that to you.

How about making up a strap wrench to hold the Collet chuck? The maximum torque that it can withstand will be the limiting factor.

As already said, the ideal is to use another collet in the R8 spindle, to hold a carbide end mill to produce two flats on the current collet chuck. The A / F size should be that of an existing spanner that you have. If there is no suitable spanner, the next job is to take a piece of 8 x 25 or 30 mm flat bar and machine a slot into to it to make a spanner.

If the worst comes to the worst, as an interim, take two pieces of 12mm square bar, clamp together and drill through both, say 5mm, open up the first to 6mm and tap M6. Centre distance needs to be about 8mm greater than the chuck OD. Using two M6 bolts of a suitable length, clamp together, with one each side of the chuck

This is bigger version of the Apprentice's simple Tap Wrench. Tighten the M6 bolts and use the gadget as a handle to hold the chuck while the C spanner is used on the clamp nut for the ER collets.

For greater grip, if you don't mind the scratches, line the bars with Emery!

One job always creates three others!

"Bigger fleas have lesser fleas upon their back to bite 'em, and so ad infinitum"

Howard

Hi Bill,

I think we are at crossed purposes, you wouldnt have to do anything to your collet C spanner that would remain as is. You need a second C spanner for the spindle hole and they are used as a pair, thats what I do.

Jasons suggestion of using a pin hook spanner for the spindle hole would be better than modifying a C spanner though.

Get yourself a pin spanner, you have your collet spanner and away you go.

Just to update, my £4.99 C spanner has arrived and is a good fit, albeit a little short-handled for me to exert the required leverage with it.

While I was waiting for it I bought another, cheaper, ER25 chuck, this time with spanner flats, which I will use at some point to mill flats on the first one when I've worked out how best to set it up for 180 degree cuts.

I have to say that the strap wrench I was using (a Boa aluminium-bodied one) to get round the problem is actually able to do the job of locking the spindle very well indeed - only downside is it's not quite as convenient as spanner.

Drill a hole in the body of the chuck for a bar, or machine flats on it.

Neil

I milled flats on mine and milled an old open ended spanner to fit. Most of the R8 er collet holders from China now have a spanner flat already on them. If you find the holder is hard, you will need a solid carbide cutter to produce the flats. 

Edited By old mart on 20/03/2020 18:54:40