Of all the tools I got....

[EdK]

(07-08-2013, 03:05 PM)doubleboost Wrote: http://www.metalworkingfun.com/showthread.php?tid=113

One of those for my ER40 collets is on my list of projects. Both a square and a hex version just like you did.

Ed

[doubleboost]

(07-08-2013, 03:22 PM)EdK Wrote:

(07-08-2013, 03:05 PM)doubleboost Wrote: http://www.metalworkingfun.com/showthread.php?tid=113

One of those for my ER40 collets is on my list of projects. Both a square and a hex version just like you did.

Ed

I use mine all the time very handy
Nice to make as well
John

[PixMan]

The reason I can't use an ER style collet for this is because they have no rigidity for holding a very short piece like the one I have to machine. The ER collets do have great grip for anything near the length of the collet though, and are nice in that they have a 1mm (.040") range in each collet.

[Highpower]

(07-08-2013, 04:33 PM)PixMan Wrote: The reason I can't use an ER style collet for this is because they have no rigidity for holding a very short piece like the one I have to machine.

Really? I did not know that. That's kind of how I feel about 5C collets. I've had to grip a very short piece a couple of times in the past, and didn't like it at all. Had to crank the snot out of the nut and even then the parts moved slightly under light cuts. Of course it's probably because my collets are imports.

I've lusted after a ER40 setup for a long time, but now I'm not so sure since I would most likely only use them for short hard to hold pieces.
I hardly ever do multiples of the same part.

[PixMan]

My 5C collets are all in excellent condition. Only if they've been used for short pieces quite often do they seem to get "sprung" open at the end. Even then, it's usually just worn to a bell-mouthed shape that causes parts to pop out. It's not a lot of grip anyhow with such a short length for the piece I want to make, so I plan to make very light cuts.

The ER collets are slitted alternately from top to nearly the bottom, and from the bottom to nearly to the top to give them that 1mm size range. Because of that range, they collapse easily upon tightening down the collet nut and if there's nothing to grip at one end you get a very cone shaped bore.

I've used a LOT of ER16 and ER20 collets to hold tools in CNC swiss-style lathes during my 30+ years work as a machinist, and never had any luck holding onto short tool shanks with them. My "rule of thumb" was that anything being clamped in an ER collet had to go in past at least half the bearing length of the collet bore. I never used them for holding onto work pieces, so things may be different (though I can't see how.)

This is a quote from the RegoFix catalog, and those are the highest quality ER collets and holders I've ever seen and used.

"Insert tool to the full length of the collet for best results
if possible. However, never insert the tool less than
2/3 of the collet bore length. Improper tool insertion
can permanently deform the collet and will result in
poor run-out."

[Mayhem]

Would inserting a slug of the same diameter further down towards the back of the collett help?

[EdK]

(07-09-2013, 04:46 AM)Mayhem Wrote: Would inserting a slug of the same diameter further down towards the back of the collett help?

I had the same thought and am curious as to the answer.

Ed

[PixMan]

Well, think about it. If you have a very short piece at the nose of the collet, you'd be OK to clamp another piece of the SAME diameter down at the opposite end of the collet. I just don't know how you get it there and hold it there squarely.

[Mayhem]

Given the length of the collett, the slug could be long enough to be able to square itself. Slide it in first and let the part you want to grip push it in for you. I guess there is only one way to find out...

[Highpower]

(07-09-2013, 07:08 AM)Mayhem Wrote: Given the length of the collett, the slug could be long enough to be able to square itself. Slide it in first and let the part you want to grip push it in for you. I guess there is only one way to find out...

My only problem is, that will mean that I won't have an extra slug on hand that isn't one size too small already - and nothing larger on hand that I could turn down to size. My local metal supply has 3 acres of storage building with racks 20 feet high full of every kind of metal under the sun.

Me - one SMALL shelf.