ER Collets

[Martin ConnellyParticipant @martinconnelly55370]

I know you have chosen Er32 but just thought I would add this. I use Rotabroach and Rotobor cutters for quite a few jobs both with the mill and the lathe. These all have 19 mm diameter shanks so I have ER32 collets for them.

Martin

[MuzzerParticipant @muzzer]

I'm a little wary of opening these matters (wounds) in the current environment, with the air full of flying handbags and toys but The Haas Guy has just posted a pretty down to earth video on the use of ER collets.

Nothing radical, just good common sense stuff as ever. A few things to pick up here if you are open to such things.

Murray

Edited By Muzzer on 20/12/2017 19:21:11

[Anonymous]

Well, that was an interesting video, and I learnt a bit – thanks Muzzer.

Andrew

[JasonBModerator @jasonb]

Yes thanks for that helped pass 1/2hr and I forgot about my back pain a bit, some useful things to remember there

For those that have the Int 30/40 type holders can I ask if they all have that back-up screw or is it just the expensive ones?

[Neil WyattModerator @neilwyatt]

Notice the swift cut as he walks away from the vending machine(!) and under the fork lift…

(Bright Electronic Music)

Very good though!

[Clive FosterParticipant @clivefoster55965]

Jason

Some makes have them some don't. Guess there is demand for both types.

But back up screws seem to be a bit contentious. With, so far as I can see, good reason on the anti side given that pull out rather than push back seems to be the major worry with a hard driven cutter in an ER collet. If bottoming the tool against the back up screw seriously reduces grip I'm darned if I can see how you can use them in a CNC centric world where most things have air drawbars acting on pull studs. Undoing the pull stud to get at the back up screw isn't going to happen.

Maybe the old style threaded shank cutters aren't such a bad idea after all. Except for the TIR problems inherent with using a screw on cap to close the collet. The Haimier system for stopping pull out looks interesting. Expensive but interesting.

This link pretty much summarises what the man from Hass was talking about :- http://usa.rego-fix.com/colletcare/. Printed out a copy for my reference notes. Dangers of over torquing surprised me. Although the mechanism is obviously theoretically possible I'd have expected other things to give up first.

Clive.

[egaParticipant @ega]

I enjoyed the video but it was sobering to be told that as little as 0.010" oversize on a tool shank would damage the collet. Instinctively, it seems better to spring the collet ever so slightly than to close it down by as much as 0.030".

By the way, are Rotabroach cutter shanks 19mm or 3/4" dia? I prefer to use them in a (shopmade) standard holder equipped with two side screws. Their intended use is not high precision, I believe.

[SteveIParticipant @stevei]

One thing to note that I don't recall hearing from the video (perhaps I missed it) is that you should tighten the back-up screw after you have tightened the collet nut.

 

Jason,

I've got QC30 ER32 and ER16 collet chucks and they do have the back-up screw. Supplied by gloster tools. The screw system is not designed as well as it might have been; it's very fiddly. There is a 4mm hex through hole in the back-up screw. So it can't be used for very small tools. The side that the cutting tools bears down on are soft (a file marks it). Over time I expect it to show wear and will need to be replaced before any deformation causes it to jam.

 

I have some ER16 collet chucks from Arrand with MT2 and MT3. These also have the back-up screw. And they are much easier to use (less fiddly) and they do not have a through hole. On the side that the cutting tool bears down on they are narrower (to mitigate against mushrooming) and are hardened. All of these details show quality and are how I think it should be. The Goster tooling is ok but it is simply not as well made.

Once again I have thoughts of its a shame the hobby has lost Arrand as a supplier. I don't know the reason that no one took over the business. Alas in the days he was still trading I did not have a QC30 spindle.

 

The above are some of the reasons that I am setting out to make my own QC30 tooling in future.

 

Who are the suppliers that don't have back-up screws in their ER collet tool holders and who are the suppliers that do? I would appreciate to know so I can decide who to buy from.

 

Edit: I wrote this before Clive posted. I do agree that with a pull stud these are a pain to get to the beauty of the obsolete QC30 system and any manual drawbar system is that you can always get to the back of the tool to adjust these.  I always use the back-up screws. 

 

 

Steve

Edited By SteveI on 21/12/2017 17:40:04

[Neil WyattModerator @neilwyatt]

He does say to tighten the collet first. The hole is for through spindle coolant systems.

I suspect that those of us who rarely remove the chuck from the mill would rather not have the back up screw?

Neil

[MuzzerParticipant @muzzer]

Well that's interesting. Although I'd seen a couple of these back up screws in my collet chucks, the penny hadn't dropped that it may actually be the default.

Just checked my collection of 20 assorted ER16, 32 and 40 chucks in 30 and 40 taper and the vast majority (I'd guess all but 2 or 3) have some sort of adjustable stop. Some look difficult to adjust after the chuck is tightened, so may not be usable in the way recommended by Haas Man.

As mentioned, the tendency seems to be for tools to work their way out of the chuck rather than into it. Probably depends what you are doing.

Murray

[SteveIParticipant @stevei]

Posted by Neil Wyatt on 21/12/2017 18:04:58:

The hole is for through spindle coolant systems.

Neil

 

Neil, of course! It's obvious now you mention it!

Edited By SteveI on 21/12/2017 18:57:58

Edited By SteveI on 21/12/2017 19:01:24

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