ER collet chuck/mill incompatibility?

I've met with a very basic problem when trying to use an R8 ER25 collet chuck in my Warco WM18: I can tighten the tool in the chuck OK, but when I try to loosen the collet nut [whilst holding a spanner on the flats of the large silver-coloured nut just below the top of the drawbar] all that happens is that the silver-coloured nut [and sometimes the drawbar itself] loosens off but the collet nut doesn't. To change a tool, I have to remove the drawbar and the entire collet chuck from the spindle and hold the shank of the chuck in a soft-jawed vice; only then can I loosen off the lock-nut. It's hardly ideal.

It strikes me that if either the collet chuck had flats on its shank or the spindle of my machine was lockable [it apparently isn't] this problem wouldn't have arisen. Interestingly, I can't see any information anywhere by retailers of machinery and collet chucks of this potential incompatibility issue.

Any suggestions for a best solution to this would be welcome. I would mill flats on the collet chuck myself if I had either a mill in which I could reliably use my present collet chuck or a collet chuck I could reliably use in my present mill! [joking]

Edited By Bill Phinn on 07/03/2020 12:11:05

Bill, this is quite a common problem.....

have the same thing on my Bridgeport and Myford VMF mill's...

on the Bridgeport use a low gear and shock the collet spanner with my hand.....

simmilar on the VMF but have to use a spanner on the quill.....

BUT u dont need to tighten the collet nut very tight in the first place.....

just a good nip is all u need.........

there are all kinds'a mod to use air guns and drill drivers to Auto / ease the change-over of tooling

but I don't need a production problem solver.....

for me using these machines is for pleasure, NOT a race.....

can't explain a good nip, but use the spanner on the draw bar nut and then give the collet ring a good nip.....

practice will help....

I've been undoing nuts and bolts all my life and can't explain the feel.....

unless ur hogging metal off on the mill the cutter will not come loose anyway.....regardless of what others may say...

never happened to me in my lifetime....and sometimes I'm machining on the edge of what should be OK....hahaha...

this is providing the cutter and the collet chuck it's free of oil and metal swarf....

I always use an airline to clean the chuck before use and cutter swap over....

if u have an old cutter u could mount it in the collet holder and try to turn it with pipe pliers to gauge how tight u need the ring nut to be......

wish I was local to show u how I do it.....sorry.......

I have an WM18, place a bar in hole provided in the spindle to hold it, there was a small tommy bar provided in the tool kit with my mill for this purpose, you should have one.

ps,

looking at the length of ur collet chuck u could machine a couple of flats for another spanner to hold the chuck body whilst u undo the ring nut I suppose.......

But I've not found it necc..........

Lacking a spindle lock you will indeed need some way of holding the collet body.

If you aren't in a position to mill spanner flats on the body maybe drilling a hole for a C spanner would be satisfactory. Best to make the spanner with a deep pad, at least 1/2", to contact the body. Ordinay C spanners tend to be abit unstable unless working on something quite solidly stable.

Alternatively some sort of hinge open collar with handles on both halves might give adequate grip. Hook round and squeeze the handles together. Aluminium on steel has a better grip than steel on steel so making the collar halves from aluminium might well suffice. Probably wont mark things either. Thin rubber pads would probably give best grip. Ages ago I used some chunks out of an old inner tube for better grip in a similar sort of application.

A screw to hold the handles together would be the ultimate but way over-engineered.

Clive

Bill

On my WM14 the silver collar goes over the drawbar. That the enables the drawbar to pull on the end of the mill spindle to draw in your tool holder and push on the inside of the silver collar to loosen your tool holder.

”It strikes me that if the collet chuck had flats on its shank this problem wouldn't have arisen”

I have a number of ER collet chucks in different sizes and they all have flats. Surprising to see one without.

I think it is the same as a PM 30 which comes with a C-spanner to hold the spindle or as mentioned above a tommy bar would fit the same hole. Have a look at their manual which also describes how the drawbar and nut are fitted and used to eject tooling.

Many thanks to everyone for your replies.

No tommy bar for the spindle hole was supplied with the machine. I tried using a piece of round bar stock for the purpose but the hole is only 5 mm diameter and the thin piece of bar bent terminally when I loosened off the nut; this is without overtightening it to begin with, which I was careful not to do.

The pin projection in the end of the C spanner that came with my collet chuck is also too big for the hole unfortunately, and it is square-section not round-.

I've found a temporary solution in the form of a large strap wrench, which just fits the spindle projection on the machine. I would still much prefer to have flats on the chuck's shank, as I'm sure a spanner applied to these would give better feedback for tightening and loosening than a strap wrench, as well as make the whole task rather easier for someone with a brachial plexus injury like me. Much as I like the collet chuck for its lack of run-out and general quality, I'm not sure I want to live with it long term without some flats to put a spanner on.

One other thing as a warning to others: if you have a similar machine and similar collet chuck to mine, don't do what I did and tighten the collet lock nut whilst holding a spanner on the flats of the silver-coloured nut just under the top of the draw bar. You risk inadvertently putting too much preload on the spindle bearings and then wondering why they are getting very warm whilst the machine emits unpleasant noises.

Edited By Bill Phinn on 07/03/2020 14:17:39

On my SX2P I use two C spanners, one on the collet nut and the other using the hole in the spindle.

Bill,

The article by Dave Fenner MEW 153 referred too above by JasonB contains the words "draw bar which is now self ejecting". This could only happen if the silver collar that your draw-bar sits on actually sits over the draw-bar.

That silver collar should be bored out to take the collar of the draw-bar and act as a restrainer when undoing the draw-bar Then with it over the draw-bar it becomes self extracting. The fact that your draw-bar sits over the collar and still is able to pick up the thread on your R8 taper is amazing.

This leads me to ask:- Is this a new machine or second hand if so has someone before you made a new draw-bar for some reason.

Please see if you silver collar will fit over the draw-bar collar if not then I believe my surmise will be true.

The penny has just dropped. You have the problem with the draw-bar and your R8/ER25 holder not having any flats.

I've given the answer to the draw-bar. The ER25/R8 holder you will have to modify when you get it out.

I was supplied with a ER collet chuck from Warco when I purchased a mill from them.

The chuck had no means of holding the body so I used a carbide end mill and machined spanner flats on it.

As the chuck body had been hardened had to use a carbide cutter it did the job ok.

Edited By Windy on 07/03/2020 15:16:29

I have an SX3 and the silly hole below the quill are a pain to use .I drilled a hole in the quill and made a c spanner to fit,now I have no problem holding the quill while undoing the collet.It is also handy for turning the qhill when tapping by the use of the c spanner.I can't understand why Sieg didn't do this in the first place.

Frank

You must have bigger muscles than me. The recommended tightening toque is about 80 Nm. as far as I remember.  However I tend to tighten them by feel.  When the force required to move the spanner increases rapidly I stop.

Russell

Edited By Russell Eberhardt on 07/03/2020 16:19:51

David, not sure what you looked at but my link is not to anything by Dave Fenner it does however tell the user how the nut and drawbar should be fitted as well as saying a C spanner is used to hold the spindle.

Looking on eBay most R8 ER25 collet chucks seem to have flats for a spanner although there are one or two without. I’m guessing then that you could machine some flats if the materials not too hard or you have a carbide mill?

Next up may be a suitable spanner. I’ve bought a couple of large ones on eBay by searching for “DIN spanner” and invariably something comes up.

Thanks a lot for the further replies.

Just to reiterate for a couple of respondents, I can't mill flats on the side of the chuck because it's the only mill holder I presently have; I'd have to buy another collet chuck, or at least a single R8 collet or endmill holder [neither of which I was planning to get] to do the work with. This assumes the material the chuck's made of isn't piggishly hard to mill, which it might be.

The Precision Matthews arrangement, with flats milled on to the sides of the spindle, looks like the best one for ensuring both types of collet chuck [both those with flats and those without] can be conveniently loosened and tightened. Too bad it's not the arrangement on my mill.

Buy yourself one mt2 finger collect and one 8mm carbide end mill to fit. Mill flats on the holder. Also buy a ball bearing closer nut for your er25 chuck. Closer needs to be tightened up very hard to hold er collect true.

MT collet won't be much good in an R8 spindle but R8 collets are as cheap.

Do you have a lathe? could probably clamp to the cross slide and hold a milling cutter in the chuck for a one off get out of jail job.

Edited By JasonB on 07/03/2020 19:43:52