Thread: Preventing collet slip & tool holder torque

Hi Stewart,
That was me asking about draw bar torque. I'll have to try that once get Mlls head back on.
As for collet tightness i obviously havn't pushed either mill hard enough as i have never had a cutter come loose. Michael G mentioned this was a problem he had and he then went to sidelock holders for a lot of his cutters.

Cheers
Ew

Originally Posted by Ueee

Hi Stewart,

As for collet tightness i obviously havn't pushed either mill hard enough as i have never had a cutter come loose.

Cheers
Ew

Same here.

Never had collet slip with my ER32 system, and I run a really large double tipped carbide fly cutter on it at high speed at times.

Not an issue with me.

I just pull it up with a safety wrench to what feels right.

Rob

Originally Posted by nearnexus

Same here.

Never had collet slip with my ER32 system, and I run a really large double tipped carbide fly cutter on it at high speed at times.

Not an issue with me.

I just pull it up with a safety wrench to what feels right.

Rob

I've managed with the "what feels right" method and avoided slippage so far.

I just had a look at the Rego-Fix site and their recommendation for tightening torque for ER32 collet nuts. 136 Nm or 100 ft lbs. for collets from 3mm to 20mm. I don't know how close I get to that with a spanner and the mill in low gear, probably nowhere but I wonder how they managed in the old days. Schaublin were selling E32 collets back in 1951 ( date of a catalogue I have ) and the chuck they fitted was supplied with a spanner of modest length. Removing a chuck to change a cutter on a stunted mill like mine isn't often a real convenience so I imagine the collet nuts would be undertensioned as would those back 60 years ago.

I imagine the 136Nm would be intended for high horsepower machining centres and not for low powered machines, in my case, 2 horsepower.

How are others tightening their collet nuts?

Bob.

G'Day Bob ,
To tighten the ER32 collet chuck on my RF 31 which doesn't have a spindle brake I hold the chuck body with a 36mm open ended spanner (an old 1 1/4" AF ground to 36mm) and tighten with the "C" spanner, I have no idea what torque I am applying but I've never had a cutter come loose.
Regards,
Martin

Hi Martin,
The nt/iso collets don't have spanner flats like the mt ones do. If I'm using one on the lathe I just use a big shifter and the safety spanner. With my hm50 I made a bench mount holder for changes.

Hi Bob,
100 ft lbs? I doubt I even get half that. With Mlle I just pit her in low and tighten like you do. The biggest problem I find is it seems to take heaps more to loosen the collet than it did to tighten them.

I almost feel like making up a crow's foot style spanner to use with the torque wrench, more out of interest than anything else.

I'm at Mlle now with the head back on, 30lbs on the db feels like less than I what I have been doing her up, but then surely nt40 would need more than R8? The hm50 is currently more like 20lbs, that's about as tight as I can go holding onto the chuck.

Cheers,
Ew

I'm now using an ISO40 version of the spindle spanner that (I think) Dave showed us and a safety spanner. My collets are ER40, but assuming 100ft.lbs, with maybe a 300mm lever arm on the spanners it means I should be pulling 100lbs (or roughly 45kg) on the end - I don't think that is happening. I may have to get a ball bearing nut and see if that helps. Interestingly I also use ER40 collets on the lathe, but don't have a problem with them. Although the forces for single point turning may be less, I also have a spindle stop to push against and can arrange gravity to assist too.

Michael

I think previous discussions on this concluded that a bench mounted fixture was the best way to tighten NT collets. I've only ever tightened in the mill, using a custom made spanner, (same as Dave made since the HM52 doesn't have a spindle lock) made to fit the drive dogs, only time I've ever had a cutter slip was with one of those carbide rippa cutters that worked it's way down slightly when climb milling. Ever since then I just tighten the collet as hard as I can, so far so good.

The collet spanner is one of these types.



And the NT30 spanner is this one, (this picture was taken just after I finished it a few years back... the paint is pretty much worn off now.. )



Regards
Ray

I was taught at Tafe to applie the spindle brake or put it in low gear and tighten the draw bar as hard as you can. At work we do the same although the drawbar gets some love taps with the copper hammer

HI ALL,
I Myself have never had a Cutter slip in a ER32 Collet. I use a 63mm Face Mill held in a ER32 Collet and that has never slipped. I did Shear the R8 alignment Pin once while using a R8 Shanked 75mm Face Mill whilst trying to see if I could Machine some Railway Iron. I guess I would have had the Drawbar at 20 ft-lb, but not at 30 ft-lb. I agree with You Bob in regards to the 100 ft-lb. I cannot see that kind of Torque being needed on a Mill Drill or a HM-50.
I tighten My ER32 Collets using a 36mm open ended spanner and the same type of Collet Spanner as RayG. I did actually Buy a second hand Clarkson Collet Chuck and Collets a couple of Years ago thinking that if I ever have a Cutter slip I was going to change over to using that. I have never used it in the time that I have had it and I probably never will.

Sort of on-topic:

Once you've tightened them, how do you release them? I use the "feels about right" method to tighten the MT4-ER40 collet chuck in my lathe. To release it I give the draw-bar a whack with a soft-headed hammer. I've always wondered if this is bad for the headstock spindle bearings. Should I buy or make a threaded spindle nose protector to act as a 'pusher' to release the collet chuck?

Something like this (although it would need a hole drilled in it to take the pin of a C spanner):

spindle thread cover

Chris

OK you blokes, you've had 24 hours to think about my question. That's long enough.

How do you release a MT collet chuck from the headstock spindle? Hammer, or something with a little more finesse?

Chris

Originally Posted by jack620

OK you blokes, you've had 24 hours to think about my question. That's long enough.

How do you release a MT collet chuck from the headstock spindle? Hammer, or something with a little more finesse?

Chris

Ok Ok.

That spindle nose protector/ejector would be the ideal means to remove the collet chuck from the spindle only if the flattened section of the chuck's arbor doesn't prevent the ejector from contacting the rear face of the chuck.

If I'm using a tanged arbor and the ejector won't work on my lathe I use a length of 20mm solid aluminium rod as a drift inside the spindle bore and knock the arbor out with a Thor hide mallet.

The little Hercus mill has no provision for a nose ejector. All the tooling I use in the mill is drawbarred. I loosen the drawbar a couple of turns and tap it with the Thor.

A lot of that tooling fits my lathe and I use the some procedure for its removal.

Given the effort, stress and sweat involved in removing the horizontal arbor from the mill when I initially acquired it, I am not over zealous when it comes to installing a Morse arbor.

Bob.

ps. Just thinking about it a bit more Chris. I made my nose protector from some easy to machine 1214. Couldn't buy one from Hercus and Mal hadn't set up shop back then. It would not be too difficult to make a protector that straddled the flattened section of the arbor (if it's in the way). Would save the spindle from a lot of hammering if you intend to use that ER40 on a regular basis.

Thanks for the reply Bob. I am constantly swapping between the ER40, 3-jaw and 4-jaw chucks as my lathe is also my mill. I think Mal's spindle protector should fit into the space nicely.
Chris

I think those spindle nose protecters are cast,he did have some made out of steel a while ago for around $35,they may be a little stronger than cast if the taper is really tight.
I collet chuck fitting directly to the spindle thread would of been better for milling in the lathe and for turning smaller stock.