Fitting ER16 Collet Chuck to Cowells Lathe

[Twizseven]

In order to make my selection of small chucks interchangeable between Cowells Mill, Cowells lathe, Aciera F12 and BCA Jig Borer I have just swapped out the mandrel on Cowells ME90 lathe from the original M14 x 1.5 to the newer M14 x 1 version..

As I wished to be able to use ER16 collets I purchased a M14x1 chuck backplate and a ER16 chuck on a 62mm mounting.  Fitted the chuck backplate to the lathe and trued up the face. it was out of true by 0.04mm.  After truing it was spot on, so then turned register down to size.  Struggled to measure this accurately so crept up on size 0.01mm steps until close then in 0.005mm steps.  Eventually the chuck faceplate was a firm push onto the register.

Checked runout by fitting 10mm collet with a 10mm endmill shank in it.  Ecstatic.  Absolutely no runout.

Now just need to repeat the exercise for the self centering 3 Jaw and the 4 jaw chuck that currently have M14x1.5 backplates.  The new backplates are quite a bit bigger and need between 18-25mm removing from the diameter.

Colin

[Jo]

I can't see why you don't go with the new Cowells Lathe standard of DA200 collets. There is a very good reason why Colin  Childs chose them unlike the ER16 collets they are suitable for holding shorter parts. ( the ER series require the item to go the full depth of the collet or you need to plug the end of the collet with the identical diameter to get it to hold correctly)

If you really must use ER collets in the Lathe I seem to recall someone does a collet chuck that goes straight on the nose and avoids the additional over hang.

Jo

P.S. Yes I have ER collets as well. Like you mentioned I use them for their original purpose = tool holding where the shanks are long enough to go all the way through.

[Jasonb]

Jo are the DA collets like 5C and MT being a fixed size?

I do use the 5C to ER adaptor when I have a job that won't fit a 5C or simply don't have that size.

Read too many people with problems getting direct fit ER chucks to run true which would put me off that way of mounting them, at least with a backplate you can make it to suit the individual machine.

Think I would rough turn those larger backplates in a bigger lathe as you could be there a while if using the Cowells

[Jo]

Jo are the DA collets like 5C and MT being a fixed size?

There is more flexibility in a DA than a 5C, mine have a 0.4mm range and a full set of 0.4mm collets from 0.4mm to 9.6mm worked out at £85.


The parallel shank at the end is the major advantage of the DA's as it helps to support the collet when holding short ends. I have held lengths down to 1.5mm in length in these accurately  An ER would have bell mouthed 

Jo

[Allen Smithee]

Read too many people with problems getting direct fit ER chucks to run true which would put me off that way of mounting them, at least with a backplate you can make it to suit the individual machine.

+1 on that. I have three direct-fitting ER32 collet holders for my Myford. I bought one and found it had 2 thou runout (no better than my 3-jaw). I complained to the supplier and he sent a replacement - that had 4 thou runout. Complained again and he sent another - it has just under 3 thou or runout. When I told the supplier he just refunded the money. I then got one of the RDG 2-piece Myford-ER32 adaptors. Took a whole three minutes to turn a nice tight-fitting spiggot on the backplate. After assembly it had no measurable runout.

The problem with the 1-piece ones appears to be the 1.25" register at the spindle end. It looks like the two ends of the part were machined in separate ops and they just aren't concentric. At some point I'm going to try boring the register oversize and pressing in a bush so that I can try putting a large collet in it and clamping it onto a piece of known-straight PGMS bar to bore a concentric register. If the result works then it will give me a "free" ER collet for a dividing head.

AS

[Twizseven]

Jo,

I can only find one supplier of a M14x1 direct fitting ER16 collet chuck and that is RC-Machines in Germany.

The overhang is exactly the same as the original Cowells collet chuck on the M14x1.5 spindle.

Other than Colin at Cowells is there anyone else supplying M14x1 threaded DA200 collet chucks.  I was not aware that the DA200 collets were suitable for holding very short parts.  Its this sort of info that this site is so good for.

Jason,
Yes I had intended to get then closer to size on a bigger machine.  Would be there all night with the Cowells.

Colin

[Jo]

Ask yourself which other lathes have M14 by 1mm noses and you will have yourself a supply of other bits to go on the nose like spare pre threaded back plates.

Other than Colin at Cowells is there anyone else supplying M14x1 threaded DA200 collet chucks.

At the price that Cowells does the English made quality collet chuck for why would you bother with anyone else  As I mentioned other places are cheaper for collets e.g. Home and Machine workshop do them for £1 each second hand, something worth picking up at the shows 

Jo

[Admiral_dk]

Jo this is a quote from the https://www.fastenal.com/ website about their 200DA060M 6.00mm DA200 Series Metric Collet:

Inserting the cutting tool less than 2/3 the gripping length into the collet can permanent damage the collet
Full length of the gripping bore must be maintained to achieve accuracy and safety

So I'm not sure about your claim about the DA200 system unlike the ER system do not require use off full length inside the collect - something I already might have done with my ER40 and ER11 collects 

[Jo]

2/3rds of the gripping length on some collets is much shorter than the length of the collet but it does go beyond the end of the reverse taper.

I have not experienced bell mouthing with DA collets, but then I am not ham fisted with any of my tools and tend to take lighter cuts when holding on a very small thickness.

Jo

[Jasonb]

2/3rds of the gripping length on some collets is much shorter than the length of the collet

ER collets are the same, the smaller sizes only have the gripping part maybe 1/3rd the total collet length.

The DA  having both rapers towards the business end will grip better but still not ideal to use for short work particularly at max close down

[Flyboy Jim]

As long as we're discussing collets for small size machines............how do the Sherline WW collets fit into the mix: https://www.sherline.com/product/individual-ww-collets-copy/

It looks like the big disadvantage is the limited range of adjustability they have. However, I think they could successfully hold quite short parts.

Jim

[Twizseven]

Interestingly having spoken to Colin at Cowells he is planning to move to a collet holder for ER16 collets, so perhaps it may pay to wait until he does so.

Colin

[Jasonb]

Well I suppose when the Cowells was first about none of us had heard of ER collets so the DA ones are a bit dated and makes sense to update to what is easily available

[JimG]

Well I suppose when the Cowells was first about none of us had heard of ER collets so the DA ones are a bit dated and makes sense to update to what is easily available

I found a source at Drill Service at prices a bit cheaper than Cowells

https://www.drill-service.co.uk/products/air-grinders/collets-and-chucks/y200da-collets-for-ag25-and-as20-grinders/

Jim.

[Bobsmodels]

I purchased my Cowells lathe a couple of years ago and it is very nice.  I purchased the DA200 collet attachment from Cowells at the same time.  I decided to try and purchase the collets myself and ran into a real runout problem with a set from a commercial supplier (not eBay).  I sent them all back.  The holder itself was dead nuts on.  After communicating with Colin he told me the specs for his attachment were from Ericson.  I purchased some original (not new ones from India I think) and they worked fine, I now have a nice set with runnouts in .0005 or less range.   I mentioned to Colin back then about an ER 16, not sure at this point I would change.

As for the question about the WW set from Sherline.  I have a full set of ww and or 8mm collets and use them in the Sherline lathe,  they work very well, just do not go much more than - .002" or you will ruin them.  I was told I could go -.004 but have not had the occasion to need that.  In hind sight a ME Cowells with the 8mm / WW spindle would have fit my work better.  The DA system works just fine.

Bob