Help on mounting ER40 collet chuck to backplate

[lobocnc]

I've got an ER40 collet chuck fixture on order from tools4cheap.net that I need to mount to a D1-3 backplate. The collet chuck plate has 3 threaded holes at 120deg. and the backplate had no holes at all. What's the best way stick them together? Just face-bolt them together then keep tweaking until the runout is zero (or close enough)? Or should I try turning a pocket on the faceplate to match the OD of the collet chuck plate and assume the plate OD is concentric with the collet chuck internal taper? What should I watch out for so as not to screw it up?
-Jeff

[Harold_V]

Before making any decisions, might be a good idea to determine how concentric the OD is with the internal taper. If you find they are concentric, it's not a bad idea to counterbore a register, so the mounted collet head can't shift under a heavy load. Assuming I was going to mount it, I'd make the register a snug slip fit (not a press fit), so the collet adapter can be removed without excessive force.

Harold

[stevec]

Lobo, Is this the adapter?

ER 40 adapter plate.jpg (26.35 KiB) Viewed 5150 times

Can you put an ER 40 collet in it and tighten it? If yes then you could machine
a concentric shaft in your lathe and then install the adapter and collet on the shaft.
Then you could check the concentricity etc. and machine the OD true (if, indeed , necessary).
Then machine a recess register in your D1-3 plate, drill and tap and you should be good to go.

[lobocnc]

Yup, that's the one. Sounds like the consensus is to true up the collet chuck plate (if necessary) and then machine a recess in the back plate. So I start by chucking up a 1" rod, true it, mount the collet chuck plate to is using an ER40 collet, and then true the collet plate OD. Do you think I'll have to worry about the weight of the collet chuck cantilevered off the 1" rod in the chuck throwing things out of whack? I'll be doing this on my spanking new South Bend 8x18 lathe.

Thanks for the help.

[SteveM]

Never saw one of those. Looks like an easy way to get a collet chuck without a lot of overhang (which you can get with some 5C collet chucks) and with the ability to pass stock through (which you don't get with a collet chuck on a morse taper).

Steve

[lobocnc]

The other advantage of an ER40 collet chuck is that it works on smaller lathes. I don't know think my lathe has a big enough spindle bore for the hollow 5C collet drawbar.

[SteveM]

The other advantage of an ER40 collet chuck is that it works on smaller lathes. I don't know think my lathe has a big enough spindle bore for the hollow 5C collet drawbar.

The 5C collet chucks use internal gears or collars with a threaded ring in the chuck to tighten the collet, no need for a drawbar, but they do extend further out:

Like this one:


Steve

[toolman49]

G'Day,
I bought the ER32 version of the same collet chuck a couple of years ago, it came with a recess machined into the rear surface. I turned a length of stock to 20mm (ER32 max) then mounted the chuck with collet to it, measured TIR of recess which was dead nuts , machined firm fitting but not crazy tight step in backplate. Blued backplate, marked holes with transfer screws, drilled backplate and bolted up. TIR in most collets is .005mm (I have a couple of dodgy ones that need replacing) I hope you are as happy with yours as I am with mine. I don't what know what material the chuck is made from but if need to turn the chuck itself be prepared for lots of sparks, its bloody hard.
Regards,
Martin

[lobocnc]

Good point - I forgot that the collet chuck is probably hardened. Hopefully the bore will be dead center, and I can reference off of that. I guess it's just the back plate that's designed for machinability.

[metalmole]

I like that idea, I checked and they are out of stock, does anyone know who else carries these...

[mclarenross]

Why not machine the backplate and chuck OD like a set-tru Buck so you can true it with set screws?