- Joined
- May 14, 2015
- Messages
- 179
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
-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