ER25 v 5C Collets

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

What I said doesn't only apply to 5C v ER25 – it applies to internal v external collets generally .

Another example – for precision work an R8 collet fitted direct in spindle is a far better proposition than an R8 arbour carrying ANY type of external collet chuck .

MikeW

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

What I said doesn't only apply to 5C v ER25 – it applies to internal v external collets generally .

Another example – for precision work an R8 collet fitted direct in spindle is a far better proposition than an R8 arbour carrying ANY type of external collet chuck .

MikeW

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

What I said doesn't only apply to 5C v ER25 – it applies to internal v external collets generally .

Another example – for precision work an R8 collet fitted direct in spindle is a far better proposition than an R8 arbour carrying ANY type of external collet chuck .

MikeW

[Adrian Parker 1Participant @adrianparker1]

Thanks for the help gentlemen; I am a little closer to a decision.

The lathe has a 4MT spindle so I am committed to some form of chuck but I do appreciate that accuracy is only as good as the fitting of that chuck to a backplate.

All of my work is Imperial due to the inability of the Model Engineering world to move into the second half of the 20th century.

ER25 should work fine but very often the metric collet will be closed considerably and I do wonder if this can effect accuracy. e.g. 1/4 inch or 6.3 mm needs a 7mm collet.

Therefore I will probably go with 5C as most applications are on a fixed imperial size ground shaft.

regards

Adrian

[Adrian Parker 1Participant @adrianparker1]

Thanks for the help gentlemen; I am a little closer to a decision.

The lathe has a 4MT spindle so I am committed to some form of chuck but I do appreciate that accuracy is only as good as the fitting of that chuck to a backplate.

All of my work is Imperial due to the inability of the Model Engineering world to move into the second half of the 20th century.

ER25 should work fine but very often the metric collet will be closed considerably and I do wonder if this can effect accuracy. e.g. 1/4 inch or 6.3 mm needs a 7mm collet.

Therefore I will probably go with 5C as most applications are on a fixed imperial size ground shaft.

regards

Adrian

[Adrian Parker 1Participant @adrianparker1]

Thanks for the help gentlemen; I am a little closer to a decision.

The lathe has a 4MT spindle so I am committed to some form of chuck but I do appreciate that accuracy is only as good as the fitting of that chuck to a backplate.

All of my work is Imperial due to the inability of the Model Engineering world to move into the second half of the 20th century.

ER25 should work fine but very often the metric collet will be closed considerably and I do wonder if this can effect accuracy. e.g. 1/4 inch or 6.3 mm needs a 7mm collet.

Therefore I will probably go with 5C as most applications are on a fixed imperial size ground shaft.

regards

Adrian

[jason udallParticipant @jasonudall57142]

Posted by Adrian Parker 1 on 09/05/2013 11:19:49:

.

All of my work is Imperial due to the inability of the Model Engineering world to move into the second half of the 20th century.

Or 21st C

[jason udallParticipant @jasonudall57142]

Posted by Adrian Parker 1 on 09/05/2013 11:19:49:

.

All of my work is Imperial due to the inability of the Model Engineering world to move into the second half of the 20th century.

Or 21st C

[jason udallParticipant @jasonudall57142]

Posted by Adrian Parker 1 on 09/05/2013 11:19:49:

.

All of my work is Imperial due to the inability of the Model Engineering world to move into the second half of the 20th century.

Or 21st C

[CHARLES lipscombeParticipant @charleslipscombe16059]

I'm not sure if I should apologise for re-opening an old post as many forum users seem to apologise for doing just this, but it seems better to me to keep related topics together – it makes searching for help so much simpler.

Anyhow…..some time ago I bought a threaded pull-through device from a local supplier for 5C collets (nothing to do with arceuro I'm happy to point out) to use in my lathe.This turned out to be an abortion of a thing, Slow to use when moving stock forward for the next item and prone to unscrewing in the wrong places.

I then read a forum post where it was suggested that a Stevenson's Collet block could be set up in a 4-jaw chuck and used as a collet chuck that was opened and closed from the front end of the lathe. This idea worked absolutely brilliantly for me. Fast and convenient.

Problem solved – except how can I hold square-section bar?

In another thread by the late,great, Earl of Bridgeport and Sumpwater he commented that Jason B had proved that an ER collet could be used to hold square and hexagonal stock, but I am unable to find that reference.

Alternatively is there a way of holding my existing 5C collets from the front of the chuck i.e. by compressing the front of the collet into a taper, in the same way that ER32 collets are closed?

Regards to all, Chas

[John HaineParticipant @johnhaine32865]

Charles, you don't need the reference. ER collets have 4 slits from each end, offset by 45 degrees. You simply find a collet slightly bigger than your square bar and tighten it down so the corners fit in the slits. Maximum gripping length is rather less than the length of the collet since the slits can't go the full length (collet would fall apart).

You can probably hold hex too but it won't fit in the slits so may not be so accurate.

I doubt this is very good for the collets.

[JasonBModerator @jasonb]

Charles why not just get a 5C chuck then all you need as a chuck key the same as a 3-jaw or 4-jaw and it's a one handed job. Less overhang than a block in a 4-jaw too. 

There are also 5C chucks that have a large handwheel an them to close the collet,

.

Yes I've held sq in an ER, will did out the pic later.

Edited By JasonB on 17/02/2019 07:34:18

[Old SchoolParticipant @oldschool]

I have both but prefer the 5c collets, I like my 5c collet chuck and the ability to hold short length that you cannot do in ER collets without a support piece. I wouldn't be without either system both have there own advantages.

[Chris Evans 6Participant @chrisevans6]

about 70% of my lathe work is done in a 5C collet chuck

[VicParticipant @vic]

Unless there’s a particular reason I’d go for ER32 rather than ER25 as there are more fittings available for them. I use ER32 on my Lathe and Mill and use them with square and Hex collet blocks and with a spindexer. I often hold square stock in a collet. Agreed about closing down to 1/4” with a 7mm collet so I don’t do it! As well as a full set of metric collets I also have 1/8”, 1/4” 3/8” and 1/2”.

[mechman48Participant @mechman48]

Posted by John Haine on 16/02/2019 23:05:09:

Charles, you don't need the reference. ER collets have 4 slits from each end, offset by 45 degrees. You simply find a collet slightly bigger than your square bar and tighten it down so the corners fit in the slits. Maximum gripping length is rather less than the length of the collet since the slits can't go the full length (collet would fall apart).

You can probably hold hex too but it won't fit in the slits so may not be so accurate.

I doubt this is very good for the collets.

I have done the same with my ER25 collet set, plus hex bar, but not for regular use. As mentioned this may be ok for odd times but don't know how this would affect the concentricity.

George.

[Nick HulmeParticipant @nickhulme30114]

Posted by John Haine on 16/02/2019 23:05:09:

You can probably hold hex too but it won't fit in the slits so may not be so accurate.

It actually works perfectly well with square, hex and octagonal

[Joseph Noci 1Participant @josephnoci1]

Andrew said:

I understood that ER collets were originally designed for hold tooling, whereas 5C collets were intended for work holding. Of course there's nothing to stop you holding what you like in any variety of collet.

I would agree. There are not many machine with a native 5C spindle it appears. There are also very few 5C collet chucks to fit 'common' spindles – The geometry just does not fit. There are ISO40, etc, chucks, but they have the rear body to take the collet, but the 5C fastening mechanism remains a dilemma in such chucks. On the other hand there are hundreds on ER collet chucks in all spindle forms, MT, R8, ISO, straight shank, etc, etc. Which generally supports the idea of tool holding rather than work holding.

There has been comment on the comparative accuracies of ER/5C – I think it is not correct to generalise on this – if the effort is made to find ER collets of better than 'normal' runout, the same effort will find comparable performance in 5C collets.

When I purchased my EMCO lathe among the options I chose was a Camlock 5C chuck – this was supplied by EMCO and endorsed by them for accuracy, etc, but is actually a BISON 5C 'set-true' style chuck. Supplied with the chuck is a set of 53 collets – 1mm to 27mm in 0.5mm steps, and a set of imperial colletc from 1/16 to 1inch in 1/32inch steps.

The collets are very good – when the chuck is set up to run with zero TIR, a 25mm collet showed 0.0018mm TIR, a 15mm collet – 0.0017mm , a 10mm – 0.0015 and a 6mm collet – 0.0013mm – That is rather good I would say!

However, those measurments are with tool steel test bars, 'perfectly round and straight, and within 0.0001mm ground diametric tolerance.

I did the same measurements with a 10mm collet and a 3/8" (9.525mm) test bar of the same accuracy as the metric bars. The 3/8" bar would not comfortable fit the 9.5mm collet and the 10mm collet required 'closing down'

The TIR increased to between 0.008mm and 0.01mm and was not consistent each fastening. Fitting a 3/8" imperial collet and the runout was a consistent 0.0015mm to 0.0016mm.

I think the moral off the story is that a good 5C collet is very good when the held item is close to the collet native diameter. I think ER collets will battle to achieve similar accuracies under those conditions, but will achieve better accuracies with wider variance of held diameter..

I realise that TIR in the 0.001/0.004 mm are small, but while we are chasing numbers..

 

Also, I am a bit confused by Jo's statement:

I have never had any issues with using my 5C's they are excellent. The mounting of my 5C collet chuck has zero run out and I have Collets up to 1 1/4" (and28mm) in all the sizes that my drawings use. Whilst I have a ER32 holder I see no point in buying any collets to go with it as it is restricted to a much smaller maximum diameter than the 5C's.

I have measured up my 27mm ID 5C and I think at a huge push I could open it up to maybe 29mm. Can one actually get a 1-1/4" 5C collet?? Thats 31.75mm..

 

Anyway, I think the first view is correct – ER collets are more versatile and a lot easier to change size in the chuck!.

The one thing I did find – I made a 4 facet drill sharpening jig, at first using ER16 collets ( of good quality) but found very poor repeatability when setting the smaller ( sub 5mm) drill bits in the collet. The spiral cutting edge of the drill always seemed to hook in a collet slit and I was forever rotating the drill bit a fraction to 'miss' a slit, etc. I then tried ER20 collets and gave up – made a new jig using 5C collets and it works fine now..I suspect the length of the ER collet is a problem in this application.

Joe

 

Edited By Joseph Noci 1 on 17/02/2019 15:54:23

Edited By Joseph Noci 1 on 17/02/2019 15:56:36

[CHARLES lipscombeParticipant @charleslipscombe16059]

Thanks to all who replied.

Jason, on reading your post I think I have been guilty of blinkered thinking.

I had dismissed the idea of using a 5C chuck because it seemed so much more trouble to install each time I wanted to use it. However I now think that if I set up such a chuck on a dedicated back plate I will be able to screw the whole assembly of clutch+backplate off the lathe spindle thread and screw it back on again next time I want to use it, without losing concentricity.

There has to be some loss of accuracy doing this but I think this might well be within acceptable limits for what I am doing (reproduction vintage motorcycle parts e.g control levers). Does this sound reasonable to you?

The idea of using ER collets for square stock is likely to come in useful someday and I have tucked it away in my memory banks for future use, However it is a ponderous way of doing repetition work compared to a collet chuck.

Chas

[JasonBModerator @jasonb]

That's what I do with mine have it on a backplate like you would any 3 or 4-jaw chuck. You will find it quicker than clocking a collet block in a 4-jaw.

Accuracy should be fine for that sort of work

[CHARLES lipscombeParticipant @charleslipscombe16059]

Thanks Jason. You have been a major help.

Chas

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