Arc Euro ER16 runout

NDIY and JH,

I think that NDIY was referring to the OPs request for assistance. Also, I have known JH for many years.

With these kinds of issues, it is difficult to figure out sometimes if the issue is with product or with user.

For example:

We as ARC have long standing customer relations with the likes of NDIY and JH... to include their representations on this forum. So, if either of you made a valid observation/comment about a faulty product, it would be easier for ARC to form an opinion about the fault, and resolve the issue quickly.

If the user is new to the hobby with limited experience, it is more difficult to form an opinion about the fault, to figure out if the product is faulty or if it is an issue with the users ability or experience. It should also be noted: If a person is a time served engineer at a blue chip company such as 'Rolls Royce' for example, it doesn't automatically mean that qualifies that person as having knowledge of a particular problem, until and unless they specifically worked on such an operation.

We do get people who wave their professional credentials at us as stick to beat us with, but that doesn't necessarily solve a problem.

And yes, ARC too can get things wrong or can take things out of context. With a certain level of respect and understanding, issues can be solved calmly.

Either way, resolutions are all presented above. Life is short and we move on.

Ketan at ARC.

On the subject of Collets,I bought a set years ago,which I use on my mill. The holder has a threaded shank so would be no use for through work,but for the moment that,s not an issue. What I would like to know is this :

How do I tell ER16 from ER25 ? There are 8 in the set from 4 to 16 mm and the holder is MT2 which I fitted with an MT3 sleeve. Have never used them in the lathe,only to hold cutters in the mill.

Just curious.

Larry, collet sizes here, go and have a measure if it does not fall into one of those then it's the far eastern ERish collets you have. Though as you can't get 16mm into an ER16 that may answer your question, could be ER20.

As the OP says he has 0.0005" runout at the chuck socket it would seem reasonable to assume the backplate and chuck are about right. Would be interesting to know runout at both ends of the tapered hole as that would eliminate a wonky chuck.

Edited By JasonB on 09/12/2018 13:29:04

Hi, this is very true about some people who have worked in jobs that you may be afraid to question their qualifications. I used to work for a big corporate company that had British Standard status, it wasn't quite a blue chip company like 'R R' but it did have some complex machinery. At times I had to correct some other workers who were new to the company, who had all these higher qualifications than myself, but what they lacked was the experience that I had gained working on these machines and the process they were used for. In my current job I have met other workers some of them machinists, who know there job well, but don't have the full fitting skills that I learnt over the years, but on the other hand I have acquired experiences that some of these people have that I never did have before. We are all learning little snippets every day, whether we realise it or not, even if it is by the odd little mishap. I can always remember a saying on the back of a box of matches (can't remember the brand, but there were hundreds of different sayings on the back of their boxes) which was pointed out to me when I first started work, and I quote; "Experience is the best form of education" and I have found that to be true.

I'm wondering if the OP has enough clearance in the corner of his register, as even if the chuck is sitting a few microns off in any one place of a true backplate, it will throw the concentricity out at the collet.

Regards Nick.

England's Glory, Moreland, Gloucester?

Thanks all again for the input.

First of all let me say that I have no complaints about the service from Arc Euro.

There are four mechanical components involved here - the backplate collet holder, nut and collet. Three of those came from Arc Euro one I made myself. Then there is a human component (me) of course. The reason for posting here was twofold: firstly to seek some help to narrow down the problem (successfully I think) and secondly to try to gauge what level of accuracy it would be reasonable to expect from the Arc Euro products.

I do really need to make this work - the price of the stuff from Arc Euro is a fairly small consideration compared to the investment of time to make the backplate.

The people telling me to do the nut up more tightly seem to be spot on. Now that I've hunted down a big enough spanner and tightened the thing up the runout has reduced to less than a thou. The runout seems to be slightly less with the 3mm Proxxon cutter shank than it does with the 3.2mm drill. This is a good result - now it is worth my while to chase down the half a thou of runout that I measured inside the collet holder taper.

I do still think that I might want to replace the nut even if it is perfect. The spanner needed to do the thing up is nearly as big as the lathe and hardly convenient to store with the lathe tooling. A nut that uses one of those pegged wrench things seems like a better bet.

For the people who asked... my backplate started out as a piece of 60mm diameter by 20mm long cast iron bar from College Engineering. Most of the machining was done on my Cowells lathe with just the final few ops done on the Unimat. I don't think the Unimat has enough slow speed torque for this job and holding that diameter would also be a challenge. The collet holder is 62mm diameter so I needed to be careful to keep as much of the diameter of the blank bar as possible to provide enough 'meat' for the three M5 fixing screw threads but I think that going up to 70mm bar would have made life tricky on the Cowells.

Finally... I'm no expert machinist but I do have an engineering background... sufficient to know that there is no such thing as perfect. Everything has an error and each part that is added will usually make the cumulative error worse. It would still be useful to see runout measurements from other people with the same (or more high end) collet setups... what is a reasonable expectation for runout from the Arc Euro products and what (if any) improvement is obtainable for more money?

Regards, Andy

Do Emco do an ER collet chuck for an SL because I'll put money on the return rate for faults being significantly lower, if any, and cocentricity being better than the maximum TIR figures Emco will quote. I know they make an ER25 chuck for the Compact 5 and the one I have is spot on. I made extended tommy bars for mine to make tightening/untightening more hand friendly.

I'm pretty sure the answer is no. The SL was replaced by the Unimat 3 a long time ago. There are pre-ER type collet holders for the SL but these usually fetch silly prices as well as requiring an older type of collet.

Regards, Andy

Indeed, silly prices, even if you can find one.

Andy, I think you'll find that the M type nut that uses the spanner with pegs has a smaller thread - 19mm rather than 22 mm. I made an ER16 holder for my Acute tool grinder, and you have to use the smaller diameter to fit the work head.

You may be able to chase down the 1/2 thou of the chuck by easing off the 3 screws and giving it a nudge in the right direction then tightening up again, a tiny skip off the register may be needed if you can't shift it with a nudge.

that leaves 0.0005" TIR from the collet and I would say at that price point you can't complain, if you want more then you need to start looking a ultra precision collets and pay 5-6 times the ARC price for them. You may get better than that with some from ARC but it would be more by luck than them being made to a gauranteed high spec. A Rego-fix Ultra precision ER 16 is good for 0.0002" TIR and cost about £35 a pop.

By way of comparison this is an ARC 10mm collet giving 0.0004" tir on my mill when fitted in a non ARC (I think) holder that has about 0.0003" tir which has been good enough for me.

Edited By JasonB on 09/12/2018 16:23:19

An example, Korloy produce ER20 collets to three levels of accuracy 0.002mm, 0.005mm or 0.010mm run-out.

'Half a thou' is probably a reasonable level of accuracy to expect from out of the box 'hobby' collets of 'ordinary quality'. Note this is the collet alone.

Richard Gordon (MEW 232) found it was quite easy to tap collets into more accurate alignment:

"Conclusions

"I never bothered with the clamp, a few light taps to nut at the indicating high position of the cutter is all that I found was needed to improve the concentricity of the ER collet system. I hope this is of use to others, or perhaps you knew this already!? By the way, I don't think this will correct for any significant errors in the spindle, nut or collet, it just re-positions the nut back to the correct concentric position after tightening. If you are still finding it difficult to achieve 0.01mm T.I.R or less, then check for cleanliness and try rotating the collet 180 deg (easier said than done, I know). If still no improvement with multiple collets, try another ER nut - I prefer the hex ones rather than the C spanner where available."

The full article is well worth looking up as though short it contains much of interest, I'm surprised it didn't generate more comment.

Neil

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If I understand correctly ... The older type of collet, E16, differs only slightly from ER16

This page is worth a look : **LINK**

http://paulthehalfwit.blogspot.com/2014/01/a-collet-chuck-for-unimat.html

MichaelG.

Its common practise in industry to clock reamers in ER collets, if they are out, slacken SLIGHTLY and tap true and re-tighten.

You can pay a staggering amount for precision collets....

Jim

I have spent a considerable amount of time looking into errors with the ER collet system. MY conclusions are , if the collet itself is not concentric everywhere, then the errors seem to multiply and get worse. The ultra precision collets are worth it in the end as the tooling does work better as it is held more concentric. ER collets should only be used with parts or cutters that allow the entire length of the collet to be engaged in the collet as well.

Another issue is the concentricity of the thread on the outer body to the inner 8 deg taper, and then the concentricity of the inner thread of the nut to the 30 deg taper. Errors in these, will prevent the collet from correctly locating and being concentric.

I have trued the inner 30 deg taper of the nut, by locking the nut onto the outer with a sleeve. Then made a chisel looking boring bar to just clean up the inner 30 deg taper. In my case a screw cut the M50 thread and then turned the shoulder in the same setup. I had made the sleeve 1st. This has corrected the cheap nuts that I brought. The other nuts with the rotating inner are junk and I found no simple way of correcting these. They will only be to about 0.02mm or so for concentricity . Yes they can be tapped to knock the item into alignment. The RegoFix 1 piece nuts with their low friction coating is concentric to better than 0.005mm when tested on my correction fixture. Did not use a better dti at the time. The cheap 1 piece nuts were out by about 0.03mm aprox. After correction, and using the good collets, a part or cutter can be held and be better than 0.01mm for concentricity all the time.

Neil

This evening I worked on it it some more and made things worse.

I found half a thou of runout on the register diameter so I gave it a really light shave. This of course lost the close fit between the collet holder and the register but I hoped that I could nudge things into place before fully tightening the screws.

It didn't work. I think the reason is that the counterbores for the fixing screws seem to be somewhat dished so the collet holder moves when the screws are tightened.

So I think that getting the register right is the only answer and it's time (another day!) to face off the register and make a new one. There is room for at least one more attempt or possibly more since I think it can be shallower than my first effort without losing any of the effective contact area.

Quite what went wrong with my first attempt at finish turning the register is not 100% clear to me. The sound of the cut was and the resulting finish were not completely even around the diameter which may be down to a lack of uniformity in the casting. Next time I will do the last few cuts with a HSS tool instead of a carbide insert, use a slower spindle speed and rather than doing the whole job in one 'hit' I will leave the thing to fully cool down before starting on the last few cuts.

Regards Andy

Emco did make an ER16 chuck and colletts for the Unimat 3, I know because I have one, bought new back in the early eighties. The back plate for it was turned on the unimat itself with no problems. Someone above questioned the ability of the Unimat to turn steel. The main problem is (or was) the abysmal system using o-rings as drive belts. Since those days mine has acquired a toothed belt drive which transforms the machine.

John

The first job I did on my SL was to make a couple of new tommy bars by turning down the ends of some 8mm steel bar salvaged from an old hoover. I had no problems at all. It also managed to finish turn and face the cast iron backplate for the collet holder.

I don't use O rings - my drive belts are orange things made by jointing some general purpose drive belt material. I don't plan to change the Unimat drive because I can put more difficult work on the Cowells. The Unimat on the other hand has ball bearings on the spindle and can spin small diameter work at a more suitable speed.

Regards, Andy

Do you have a counterbore or endmill that you could use to flatten off the faces?

Martin.

No, my Proxxon miller only goes up to 3mm. In time I may get some bigger cutters for use with the vertical slide on the Cowells but at the moment I have nothing that large.

Regards Andy

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**LINK**

http://www.nielsmachines.com/en/emco-unimat-3-collet-holder-er16-and-5-rego-fix-c.html

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But listed here as using ESX 16 collets : http://www.rejon.co.uk/Unimat_2016.pdf

The plot thickens !

MichaelG.

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Update: Quoting from another forum:

https://www.practicalmachinist.com/vb/general/noob-questions-about-collets-especially-er-collets-269209/

Sounds like you figured it out already... but ESX is indeed exactly the same in all design respects to ER. ESX are only termed such, though, by Schaublin. There is a historical reason for this, but it is really not worth getting into here. The Schaublin ESX collets are high quality, Swiss made collets equivalent in precision to Rego Fix (also Swiss manufactured). The reason I bring this up is to emphasize the quality of the set you already own.

Edited By Michael Gilligan on 09/12/2018 23:07:46