Arc euro do a separate chuck and backplate, I used their chuck and a D1-3 adaptor from another supplier ( Arc don't supply D1-3) for my current lathe and very pleased with it. They sell a pre machined Myford backplate so an easy adaption. Previously when I had an ML7-R I bought a one piece ER32 chuck from RDG to screw straight on the spindle thread, this was so far out in terms of concentricity and alignment it had to be returned and I purchased separate chuck and backplate from Arc which after some simple machining of the backplate register was as accurate as I need to be.

Edit John is a much faster typer!

Edited By Dave Wootton on 15/08/2023 12:38:30

ER holders are available to screw directly on to the Myford spindle nose. Try looking on Arc Euro, Chronos and new Myford / RDG websites, they should be available in ER 25 and ER 32 sizes.

The backplate ones do have the advantage of being easy to tweak should you find any runout issues which are not so easily dealt with using the direct screw on types.

should you find any runout issues which are not so easily dealt with using the direct screw on types.

Amen to that.

I bought a Soba branded one piece Myford nose mounting ER collet chuck from one of the Harrogate ME shows several years ago, but left it a long time before getting around to trying it on the machine – too long to try for an exchange or refund when it turned out bad. It didn't screw fully onto the Myford spindle nose and was pot hard – took ages to lap it to fit using a soft 2MT Myford nose adapter to carry the compound.

Then, when it did (eventually) screw on up to the spindle shoulder, I found that it had excessive runout in the ER taper. I can't recall exactly how much runout, but it was several thou, which rather defeats the idea of a collet system. I may get around to regrinding the taper socket in situ at some point to try to make it useable, but a 2 part design like the RDG Tools item would have been a lot easier all round.

After a couple of bad experiences with Soba stuff, I positively avoid it now & always try exhibition purchases for fit & accuracy as soon it gets back home.

Nigel B.

I have an Arrand screw on type . If you can find one of those, then grab it. They are extremely accurate and I can detect no run out on the collet angle.

Andrew.

Russell, I assume your home made one had the taper turned in situ so I would expect that to run true

It's when you screw a shop bought one onto a possibly worn or abused nose that things can cause problems, there have been several threads on here where that has been the case if you can get the chuck to even screw on in the first place.

I bought a large bore Myford at the final sale.I asked Chris More if he had a faceplate as it only came with a 3 jaw.He told me all stock was with with RDG.I told him I needed a collet chuck for it and he said he had one in his desk which he sold me for cash at 50 gbp when opened it it was a ER25 so I have made a ER32 screw on adapter for the lathe,I have thought about makeing another but ER 40. The Myford ER25 adaptor is on a backplate which is removable so a chuck adaptor can be fitted.

Thinking of making a direct screw-on type for my Boxford C, but not sure whether to go for ER32 or ER40. Any suggestions which might be preferable?

Thanks,Rob

What's the spindle bore? I got ER40 for my big bore Super 7 to accommodate the maximum diameter the bore could but otherwise ER32 would have been fine.

If it is any help,

ER32 collets will accept work up to 20 mm diameter, which is 0.7874"; a shade larger than your 3/4" nominal bore.

ER25 atb 16 mm is just smaller so not much use to you.

FWIW, I would favour a backplate type collet chuck, so that longer work can extens into the spindle bore.

When I fitted a chuck mto the backplate on my lathe, I coated the surfaces with anaerobic sealant, and with the bolts lightly nipped, clocked the taper bore until it was within 0.0005", before fully tightening bthe bolts and rechecking.

Howard