ER40 Collet Closer

[barnbwt]

In recent months, I've become a big fan of ER40 collets on my 12X28 lathe, since they are;
-So grippy compared to any kind of tailstock chuck
-So much faster at getting a low-runout turn at the spindle
-So rigid that chatter/harmonics are totally changed (for the better) on my machine; it cuts like a heavier verson of itself when I've got collets holding drills or stock, or both
-Large enough for 1" stock, so it's not often I feel restricted cutting anything that needs a collet vs. chuck/centers
-So compact they take up practically no room on the spindle or bed; almost like using Morse taper tooling, but even lighter weight

Unfortunately...

...changing out and tightening the collets is kind of a pain. I really like how simple (and cheap) the collet holders & chucks are, but the threaded collet-nut needing a spanner wrench and truckload of torque to cinch down is a real downer if you're having to manipulate the collets a lot. Especially when doing a series of drill operations that require indicating, spotting, pre-drilling, drilling, finish drilling, and reaming (for a gun barrel chamber, for instance). This is why ER's are normally part of tool holder setups like CAT or Morse Tapers, so you don't have to fiddle with them as often. This as you may imagine, is more expensive, considering there's 23 collets comprising the range of diameter from 1/8" to 1".

I think the 5C guys have it figured out, as far as having a spindle-mounted arrangement that uses a chuck wrench and considerable mechanical advantage to quickly swap & snug a collet down, as opposed to pure muscle like something out of the steamfitter days. Sadly, nothing similar exists for ER's that I know of, just some insanely expensive pneumatic fixtures that don't even spin. ER collets are a little different from others in that they are pressed into a tapered socket from the front as opposed to pulled in from the rear, but I think an ER40 collet nut threaded on the outside, could be drawn back down onto the collet to compress it similar to the 5C shown below (only the ring-gear would be on the nose-end of the assembly & pulling on the collet nut). You'd need to key the nut against rotation just like 5C's or R8's are, but I think that's all there would be to it. The threaded nut would still have the internal taper and lip to properly tighten as well as extract the collet as the ring gear's rotation drives it in and out of the chuck, so you'd back it all the way out of the assembly to remove the collet, same as for a 5C (but with an extra moving part)

One would actually be able to make non-collapsing solid tool holders that plug into the same socket very easily/cheaply; two tapers, a tapped hole for the set screw, and reamed for the desired size (or merely reamed if you are set up to do shrink-fit carbide tooling)

Even better would be a lever-style closer at the far end of the spindle, but I don't see how that'd be doable without violating several laws of physics; seems expensive. I'd even settle for a powered ball or lever-locking system like the CAT holders do to secure the things, since a true quick-change arrangement would be ideal, but that also seems difficult & expensive.

TCB

 

[Bob Korves]

A hand wheel 5C collet closer is also a good setup. Accurate, as quick as anything but a lever type, relatively cheap, can make one yourself.

 

[kd4gij]

If your are only holding stock, and using the proper size collet. You do not need to torque it much. I just snug it up works fine.

 

[barnbwt]

A hand wheel 5C collet closer is also a good setup. Accurate, as quick as anything but a lever type, relatively cheap, can make one yourself.

Indeed; I believe they operate similarly (only the handweel is a second ring-gear with some mechanical advantage). I like the versatility of 5C (stepped & shaped collets), but it lacks large through-bore capability and larger contact areas of the ER series. Apart from the closure difficulty, it really does seem like the ER's are pretty ideal for everything but really short or non-circular items.

If your are only holding stock, and using the proper size collet. You do not need to torque it much. I just snug it up works fine

True; I don't ever go to the full 100 ft-lb or whatever crazy number it's supposed to be. I don't think you could even get there safely without the ball-bearing collet nuts. I often find myself considering buying a second set of collets simply to bore them up one half size, even though it's really not needed. However, I am considering ER40 as the primary spindle system for a higher speed mini-lathe project (5000 rpm) so I'd be wanting things pretty snug for that.

Something with the convenience of the handwheel setup is what I'm after, but for my preferred choice of collets. A true actuated quick-change system would be really cool, and I'll look into that as an option if it seems viable, but screw-on/screw-off collet installation without the workout would be a huge step up.

 

[Bob Korves]

Indeed; I believe they operate similarly (only the handweel is a second ring-gear with some mechanical advantage). I like the versatility of 5C (stepped & shaped collets), but it lacks large through-bore capability and larger contact areas of the ER series. Apart from the closure difficulty, it really does seem like the ER's are pretty ideal for everything but really short or non-circular items.

I am in the middle of making one. Some examples:
http://www.hobby-machinist.com/threads/collet-adapter.30906/
http://www.homemadetools.net/homemade-collet-closer
http://kinzers.com/don/MachineTools/collet_closer/
http://www.hobby-machinist.com/threads/make-a-collet-closer.1748/
This style collet closer is as accurate as the spindle taper and the 5C adapter are, and can be trued in place with a tool post grinder or equivalent to essentially perfect repeatable accuracy by indexing them. It is cheap and relatively easy to make. It is quicker than collet chucks to change collets, and more inherently accurate. It holds collets tightly, quickly. It accepts 1" round through stock, and round work up to 1-1/8". It can be changed to a 3 or 4 jaw 5C collet chuck
http://www.ebay.com/itm/SHARS-4-4-J...LET-ARBOR-SHANK-TAPER-MOUNT-NEW-/350982812341
for work held in jaws in a minute or so, and back again just as quickly.

 

[barnbwt]

I guess you're right about 5C's going up to 1-1/8" --I remembered their shank being narrower than that for some reason. ER's still have the flexibility advantage, and a larger gripping surface with less tendency to mar parts. They're also a good bit shorter overall, though I think both would work fine in the ~8" spindle length I'm dealing with.

And even though I have some reservations about the rigidity of that 4-jaw setup, it does demonstrate that the pure versatility of 5C is pretty much peerless. That, combined with the ease of closing a 5C through the tailstock, does make the idea of a 5C spindle very interesting to me. Could always make an ER40-5C adapter along the lines of the large Morse taper ones unless I'm missing something (don't know if I'd bore a 1" hole through that 1.25" shank & subject it to heavy side-loads, though)

Sort of like a hollow R8 setup, or like how you see CAT spindles with ER tool holders. As with R8, I don't care for how 5C only grips at the very front on three contacts if there is any real collet deflection, but I do see the potential as a solid-shank tool holder that still has large through-bore capacity. Has anyone rigged up an actual quick-change system that doesn't require unscrewing the 5C's? Again, sort of like the CAT pull-stud arrangement, but hollow?

TCB