Done up correctly you will have to try very hard to push the cutter up or have it pull out of an ER chuck.

Threaded, plain and Weldon shank cutter s can all go into an ER chuck

Speedy, I have both Clarkson and ER32 collet chucks and both hold equally well under normal use. However, if I have a threaded mill suitable for use with the Clarkson – then I always use it.

I have had a mill move out of a collet chuck when working it hard (on a large Bridgeport mill – with a large & expensive work piece that I'd just surface ground externally) – and it didn't move out just a few thou either. I cannot remember the exact set-up details now – I guess it was probably an MT-type collet chuck (non-Clarkson) with a 1/2" mill fitted (which I know was tightened up) but I can certainly recall how pee'd off I was at the time with the unwanted groove it cut.

So although I've never had a problem with my ER chucks (and nor should anyone else under "normal" circumstances) – I still prefer to use the Clarkson when given the choice. Frankly, it just makes me feel better…

Regards,

IanT

Hi Bob,

Where I live milling cutters with a threaded end is very rare, Weldon is the normal, so I use ER collets to hold my milling cutters, I also use ball bearing collet nuts and have never had a cutter move in or out of an ER collet.

Thor

Interesting! I have just gone down the ER route having previously used a similar tapered collet system but with only 3 slits down the collets. I also have a pucker Clarkson for the (increasingly rare) threaded enders.

Anyway, first trial with the ER25 set showed the cutter was pulling out on a modest cut with a freshly sharpened 16mm end mill on 6082T6 ally. Maybe I need to be a bit more ham fisted in the spanner department? Even so, it took a fair bit of getting out again. The ER25 set was from Chronos, fresh from China.

The bearing collet nut sounds interesting – are they on e-bay or similar? Should I bet putting little grease round the inside of the closing nut as an interim step?

Martin

I think it ought to be possible to use a nut on a threaded cutter behind the ER collet. This might require the nut to the thinner or smaller diameter than standard, but if you really are concerned about the cutter moving this could be an answer. In my experience they don't come loose anyway.

Cheers, Tim

Thanks for the link Thor – they look like pretty high torques to get on the C spanner as supplied! Certainly a bit more than these arthritic hands can cope with these days.

Jason, Yes I am up to speed with locking the collet into the closing nut.

Thanks to you both.

Martin

I have one collet chuck (ER11) with a hex nut and two (ER25) with the slotted nuts, and much prefer the latter as long as they are used with the "industrial" type spanner that locates with the nut in four places. Changing to this from a C-spanner was a revelation.

Brian

Oddly enough I find that just about every cutter that I have will stay in the collet when loose so that leaves me both hands free to use the two spanners (mine has flats too) The only time I need to support a cutter is when using drills that are less than nominal size of the collet plus about two cutters that seem to have a fractionally undersize shank. I do have imperial collets for the imperial shank cutters.

Martin is right. There are some which don't have flats on the main body – perfectly normal. In such cases, spindle lock/find some way to hold spindle/spindle drawbar/peg type spanner with location pins (usually supplied with machine specifically for this purpose) to hold certain spindles at the bottom/ or grind flats on body as suggested.

Ketan at ARC.

Edited By Ketan Swali on 18/03/2018 13:09:54

Don’t make a lot of difference. I still cannot tighten down some of my collets, by hand, to grip the minimum size for that collet.

No problem with first half a mm, but not for 0.9mm ( for example) under the nominal maximum size of the collet. You might be able to, but I can’t. So fitting a nut to hold some threaded end mills in the collet while tightening with two spanners, requiring both hands to be used, seems to me to be a good tip if changing tools repeatedly.