Pros and Cons of the ER collet system

Exact size on size would be needed to avoid point contact Martin. A condition that is highly unlikely to be achieved in practice.

The plus of ER against the negative aspect is that one collet can hold a small range of sizes. That isn't the case with typical traditional collets. Stuff that is to be fitted into them needs to be pretty close to the correct size.

I suspect that the radial myth comes about because traditional collets are keyed to prevent rotation. They need to be because the taper part is only designed to close the collet onto the work. If used on R8 for milling sizes need to be pretty precise as well.

Comments about Berhard don't fit in at all with my training. They were referred to a bar chucks and for use turning bar where the od isn't going to be touched and accuracy isn't that important. I'd expect up to a couple of thou or so error. Their grip length is also pretty long. For real work I was told to use the ones that came with the lathe I was using. On things like CVA, Langs, DSG's there are rather a lot of them, For the size range they cover there is rather a lot with my Pultra as well.

Crawford specify accuracy some where in their catalogue. My recollection is that it's not a lot different to standard ER that have been made correctly. Like ER there are probably higher spec ones available.

I'm as bad on work holding collets as are some others. I've had my Boxford for some years now and it came with collets that may well have been bought with it. Still in preservative. Lathe dates from 1977, probably 3 owners. I've had the size of Burnerd multi grip that was supplied to go with Myford 7's for a long long time along with a boxed set of the collets. I've never bothered or had the need to mount it. Worse still I recently bought a Jacobs version. There is a reason though, chuck type rather than lever and I tend to worry about not having larger sizes of collet in case I need them. Crazy really as correctly machined soft jaws will hold work pretty precisely. Some think that the scroll in a 3 jaw must be miles out and will wobble all over the place. They don't. Maybe cheap ones do.

I have ER16 and E25. I spent some time wondering about that. I don't really want ER32 or ER40 dangling on the end of my millers spindle. I was sort of tempted to ER32 but there isn't much of a gain over 25 really in cutter size as far as machining goes so I will adapt a 25mm indexable end mill and past that I feel that a face mill make more sense.

Some one passed a comment on here about 5C collets on here. I was thinking of buying a set and a chuck. The comment was don't. I did and have scarcely used any of them so if you do buy as needed.

Really the best all round answer is to think how to make things in one setting as then they aren't needed. Next comes ok can't do that entirely but I can still ............. what ever solution crops up. I find there usually is one.

John

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Interesting comment about 5C sets vs. individuals. I would say I have used 75% of the ones in my 1/32" increments set in the couple of years since I have had them. Yet it was something like 40% cheaper to buy a set than individuals so by my reconing if you only use 60% of teh ones in the set you are quids in.

Set of 29 = £109, 29 individuals = £174

J

Edited By JasonB on 05/09/2016 21:06:21

Always assuming that the clamped item is a true cylinder and not a cone.

Andrew

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Michael Horner,

What I believe to be the original Patent states the following Claims:

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As you will see; the claims do not include any reference to the 'intention' [in the sense of what it's intended to clamp] ... This Patent concentrates on the benefits of the circumfrential groove.

Now: For your 'homework' ... 

See if you can find the Patent, and the ones that build upon it.

MichaelG.

Edited By Michael Gilligan on 05/09/2016 21:34:06

I don't think it will Ian. As the collet closes in on itself, the radii of the segments stay the same, but contact at a smaller diameter of the cone.

Martin.

Yes I see your point.

The more we look into this whole collet business the more one realises how imperfect they ALL are.

The cone within a cone only make full metal to metal contact in one axial position, for the ID of the collet to reduce the collet has to move axially so immediately compromising the fit.

I suppose we could liken collets to the bumble bee which carries on flying even though the laws of aerodynamics say that it too heavy (or something)

I am happy with all the collets I have and use, 5c, ER16, ER25, MT2, Bosch router, Dremel, (actually Dremel no!)

Ian P

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Very true, Andrew

... Or indeed one of many other mismatches of shape.

MichaelG.

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John,

Could you explain (a) please ? ... [do we have a different definition of the word radial ?]

I totally agree with (b) ... to the extent that it is possible

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MichaelG.

Edited By Michael Gilligan on 05/09/2016 22:32:25

It initially started off as a tangential force but got repeated by so many people that it turned into radial as each person whispered it to another.

Myths always change like that.

John

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Aha ... A 'factoid'

[Using the word as coined by Norman Mailer, rather than as recently abused by some radio DJ whose name I don't recall.]

If that's the case, it might explain some of the differences of opinion that are evident in this thread.

MichaelG.

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Deep breath everybody ... When some people say 'radial' they might mean 'tangential'.

... Is there any hope ?

The claims of a patent would not state the intention. They only describe the features that are protected. The intention might be described in the specification, but that is only descriptive text.

Totally confused now.

Radial force should be side acting along the radius through the centre.

Axial should be end acting coaxial with the collet.

Torsional should be rotational about the cylindrical axis.

For all the uses I put the things to they work admirably so I cannot see what all the fuss is about.

regards Martin

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Quite so, Martin

... That's why I raised the point.

The mis-use of these terms might well be what has caused so much difficulty.

MichaelG.

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The whole document is properly referred to as a 'Patent Specification', and, in this specific case, there is no more description of what the collets are intended to hold.

... I quoted the 'Claims' only because they are concise.

MichaelG.

It could be that some one sees torque as a radial force. I have come across that before., I assume because the leverage used to apply it could be radial

There are only broadly speaking 2 types of collet. Both use tapers to close. One uses a key to prevent rotation and the other uses the taper.

John

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Edited By Ajohnw on 06/09/2016 09:48:40

Lucky I haven't binned my Clarkson Autolock yet. Sounds like this ER idea is a load of rubbish!!

Mike

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You may want to think that one through, John

MichaelG.

Michael P, ER's are certainly not a load of rubbish [but I think that you said that with tongue firmly in cheek ]

What im trying to find out is WHY the ER's system is not at it's best when dealing with heavy Radial loads There IS a fall of in performance when dealing with that force. They still work, but are not the best when dealing with Heavy Radial loads.

I await a reply from the following companies, Rego Fix, Schunk, Albrecht and Fahrion. I will find out the reason eventually,. and put the findings on here.

I don't need to Michael. As I mentioned I have seen the word radial force used to describe torque so you do. To me torque is torque and how it's applied is irrelevant.

John

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If you use the BIG brand ER colets, they are far better than the Regofix and all others. I don't have them myself as they are too expensive for me. These hold cutters a lot better than any other ER collet and their collets only have a 1/2 mm range in size with a recommendation of using them on the nominal sizes. For holding milling cutters, you can't beat a shrink fit system with good quality shrink holders and an induction heater system for installation and removal. Mainly carbide cutters are held in the shrink system. The earlier video was a bit misleading by not showing the 1st test at real speed and sound. The second cutter should have been in a new path instead of going in an existing slot. For home use the appropriate ER collet system size is important to get the most out of the holders for cutters. Using a bigger longer collet is only good if the cutting tool is still held by the full length of the collet. I don't see any point using an ER32 as an example when the length of the 4mm end mill does not allow the too shank to be fully supported. Then you are better off to have a shorter collet chuck like an ER16 collet chuck for example or the even smaller ER11 collet chuck.

Neil