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View Full Version : ER Collet quandary



QSIMDO
03-07-2009, 09:48 AM
I appreciate the quick-change aspect of ER collets but it seems they hold a tool quite far from the spindle when used in a milling machine.
A problem or not?

John Stevenson
03-07-2009, 10:19 AM
So do most commercial machines using INT and BT series collet chucks.
It's only the HSM crowd who have had the dubious advantage [ cost wise ? ] of holding collets direct in the ends of spindles who have had the minimal overhang advantage.

Could be a cost issue, could be lack of daylight on small machines, could be the wimpy R8 collets on Bridgeports ..........now look you have got me started :rolleyes:

One answer is to machine an ER fitting direct onto the spindle.

http://www.stevenson-engineers.co.uk/files/X3nose1.jpg

.

lazlo
03-07-2009, 11:22 AM
I appreciate the quick-change aspect of ER collets

ER collets are not quick change. You have to snap the collet into the nose nut, and then screw the whole assembly onto the ER chuck body. You're supposed to torque the nut down to ~ 60 lbs.


it seems they hold a tool quite far from the spindle when used in a milling machine. A problem or not?

The ER collet chuck does reduce the rigidity of the quill.

This is a picture when I was using a ER-40 collet chuck on my Millrite -- it sticks out about 2 1/2" more than an R8 collet with the same tool would. That servo plate is 10" in diameter, for reference:

http://i164.photobucket.com/albums/u15/rtgeorge_album/Servo%20Plate/ServoPlate015.jpg

QSIMDO
03-07-2009, 04:59 PM
ER collets are not quick change. You have to snap the collet into the nose nut, and then screw the whole assembly onto the ER chuck body. You're supposed to torque the nut down to ~ 60 lbs.


When you have arthritis as I have they could be friggin' welded to the spindle and be "quick change", capice?

lazlo
03-07-2009, 05:02 PM
I'm not sure I follow Len, but if you have arthritis, it's probably going to be easier for you to screw in an R8 collet, than to torque-down on the ER collet nose with the pin spanner they use.

QSIMDO
03-07-2009, 10:09 PM
Gross movements are now so much easier than fine manipulation of fingers and wrists as in twirling the draw bar to thread into a collet.
Things we don't even think about normally I now need to look for short cuts...but hell, many have it worse than I so I'll stop complaining.
It's enticing to have a snap-in collet charged with the appropriate sized cutter just sitting there waiting...yeah, like I'm under some deadline.

It's like having "Tim The Toolman" sitting on your shoulder saying "Ohhhhh, look at that collet setup, HO, ho ho, ho ho!" ;)

Mark Hockett
03-07-2009, 10:28 PM
Why not just add a power draw bar to the machine, Then all of you tooling will be easy to change.

Timleech
03-08-2009, 08:02 AM
The actual projection will vary with your spindle taper and choice of chuck. Lazlo's does look a bit extreme.
On a 30 taper, my ER32 chuck brings the nut 1.75" below the spindle face, I do have an ER40 which is a bit more at 2.25"
Probably less overhang than with the equivalent Clarkson (threaded cutter) collet chuck.

Tim

Bguns
03-08-2009, 08:18 AM
TG series handles that... on a 50 taper Machine at least.. With different Projections available..

On the Smaller Machines ER is fine, but by no means Quick Change...

It all depends on what you have ...

If a little R8 Spindle, you will have some loss of ridgidness due to the overhang on smaller Spindle Diameter Bearings, but also not that much HP to push out of whack..

Use what you have, and if that does not work, get a bigger machine

John Stevenson
03-08-2009, 08:39 AM
Yes the Clarksons were a bit extreme but a good system.
I have a speed increaser for my CNC mill for doing small hole work it's either 1:4 or 1: 6 [ can't remember I have two and not sure which one this is ] but it has a fitted Clarkson chuck that can't be changed, Problem is Clarksons only come with 1/4" collets as the smallest, or 6mm, there are no others.

So I use a tiny parallel shanked 16mm to ER11 collet chuck in a 16mm collet, then hold the drill in that.
Sounds extreme but it's the best of what I have, using small stub drill it measures 7- 1/2" from spindle to tip of drill :eek: but it's a testament to the makers of the various parts that there is no measurable run out on my welded Micron gauge :rolleyes:

small.planes
03-08-2009, 08:49 AM
I use ER32 and ER16 mostly in my INT40 TOS. The 32 does step down from the quill size, but I dont think it is to weady:
http://i306.photobucket.com/albums/nn274/small_planes/SSC_4450.jpg
Thats a 16mm endmill in the collet for scale, from the last job I ran.

This is the ER16 tool holder held next to the 32 in the quill.
http://i306.photobucket.com/albums/nn274/small_planes/SSC_4451.jpg

And the ER16 holder. I use this a lot as a 'drill chuck', as I dont have a 40 taper drill chuck, and the er16 collets I have a full set from 0.5mm to 10mm. I find the collet change is probably as quick as a drill chuck, especially as I have acres of mill table to leave things lying close to hand.
http://i306.photobucket.com/albums/nn274/small_planes/SSC_4452.jpg

Dave

lazlo
03-08-2009, 11:02 AM
I use ER32 and ER16 mostly in my INT40 TOS. The 32 does step down from the quill size, but I dont think it is to weady:

The problem with the stickout on these adapters is because they have the collet chamber starting outside of the quill.
I'm looking at an INT40 I use as a paperweight on my desk, and there's plenty of meat there to put an ER40 inside the quill, so that only the nut would stickout.

With R8, you might be able to fit an ER16 up inside the quill.

QSIMDO
03-08-2009, 11:36 AM
I think once over & done, Mark has the right idea.
Bob Warfield made what looks to be an effective power draw bar, though I do still like to "feel" how things are tightening.

I should have phrased my initial question more accurately to ask what would be a reasonable distance for tool spacing with ER collets in a R8 spindle...but then that too would be based on speed, feed, material, etc. wouldn't it?

To hell with the ER's I'll spend my money on a solid parting setup! ;)