Straight Shank ER Collet Chucks?

[hornluv]

I've seen these straight shank ER collet chucks in the Enco flyers and was wondering a few things about them. Is this the kind of thing that you could chuck up in the four jaw to give you the advantages of collets while still being able to turn larger stock if you need it? It looks to me from the pictures that the chuck is tightened using the nut at the front end of the chuck (the end with the collet) rather than a draw bar. Is that correct? Is there a through hole in the shank? If so, is it the same size regardless of the shank diameter? I'm looking at an ER 32 and they are available in 1, 1.250, and 1.500" diameter shanks. I mainly want it to make machining thin walled tubing a bit easier and faster. Anyway, I'd like to know a bit more about them before I spend some coin on them.

Thanks,
Stuart

[John Stevenson]

Stuart,
The ER32's can go up to 20mm or 0.787" max size.
It should state on those collet chucks what the internal bore is.
The two bigger sizes should be able to clear max diameter but the 1" one may be a bit shy.

I have a faceplate mounted one and the clearance hole in that is far larger than the max size of collet.

The straight shanked chucks can be held in 3 or 4 jaw and yes they are front tightening.

HTH.

[hornluv]

Stuart,
The ER32's can go up to 20mm or 0.787" max size.
It should state on those collet chucks what the internal bore is.
The two bigger sizes should be able to clear max diameter but the 1" one may be a bit shy.

I have a faceplate mounted one and the clearance hole in that is far larger than the max size of collet.

The straight shanked chucks can be held in 3 or 4 jaw and yes they are front tightening.

HTH.

Thanks John. That's just what I needed.

[suprdvn]

I use that type of collet chuck all the time. Most also have internal threads in the shank for use with a stop. That really comes in handy once in a while.

[nheng]

The straight shank ETM brand ER-25 collet chuck I have does not have a thru hole. Neither does an MT3 imported ER-40 set. The threaded spindle mounted ER chuck(s) that I've seen do have thru holes.

On the straight and MT shanks, the depth is only several inches, a real limit on stock handling, cutoff, etc.

One thing you might want to consider if you can cut an accurate taper and thread, is to make your own, WITH a thru hole. The nut is really key to the whole operation as it has an eccentric shoulder on the inner front. You tilt the ER collet and snap it into place, whereupon it spins loosely until seated. This shoulder is critical as it extracts the ER collet when your work is done

Zero out a piece of either tool or mild steel (either should last a while in HSM use) maybe 1-1/2" diameter in the 4 jaw and have at it ... creating the bore, taper and thread without removing it. Since you cut the taper without removing the rod, your home made taper will actually have less runout than the collets ... even high accuracy versions

An ETM nut will only set you back around $40 (Travers and other tool places).

Den

[ulav8r]

Nheng,

Check yours closely, all I have seen have a through hole and come with a threaded plug that is used as a stop. The plug is usually near the middle of the spindle and it looks like the hole is a blind hole. Close inspection will find a screwdriver slot in the plug that allows adjustment or removal.

[nheng]

ulav8r, you are absolutely correct ! Not only is there a threaded hole but it isn't even plugged The only feeble explanation I have is that my shop lighting used to be extremely poor back when I got that chuck. All I recalled was a black hole.

That feature will help on small diameters and as a matter of fact, using a tube for the draw bar will accomodate even longer, small diameters. Thanks!

Den

[ulav8r]

You're welcome. Purchased 11 of these recently from MSC, they had the plug in them. Some I got through a local distributer about 8-9 years back in Omaha were the same way. Should be (but might not) standard on all straight shank chucks, might be missing on taper shank chucks. The reason I say it should be standard is that these chucks are often used for cutting tools that need to bottom out against a fixed stop, such as drills or end mills.