Collet chuck for Chester 920 Lathe

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Collet chuck for Chester 920 Lathe

This topic has 12 replies, 9 voices, and was last updated 18 March 2021 at 10:33 by Howard Lewis.

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17 March 2021 at 00:41 #14205
Erik Shepherd
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@erikshepherd56460
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17 March 2021 at 00:41 #534291
Erik Shepherd
Participant
@erikshepherd56460
Good evening gents,

Please excuse me if this has been covered before.

I've had my Chester 920 lathe for some time now and tweaked it to the best of my abilities, namely the 4 hole toolpost mounting plate, which made a world of difference.

I've been eyeballing getting a collet chuck for some time (most likely ER32), however, because the spindle is threaded, I'm running into issues due to the fact that I'm not entirely sure what will fit.

https://www.arceurotrade.co.uk/Catalogue/Collets/ER-Lathe-Collet-Chucks/ER32-Lathe-Collet-Chucks?gclid=Cj0KCQjwrsGCBhD1ARIsALILBYqFNbTZVke-CVExl3-MlchjIUO-DqYkhTaN_FUOcEnqcnQR36pxORAaAjjQEALw_wcB

This is the one I've been looking at, and I've had good experiences with ARC in the past. However, as far as I understand, these are for lathes that have backplates that screw the chuck on, rather than threaded spindles.

Could anyone advise on what chuck would be appropriate for my lathe?

Cheers

Erik
17 March 2021 at 04:05 #534297
Paul Lousick
Participant
@paullousick59116
You have to get a backplate to match your lathe and attach the collet chuck to it.

I use an ER32 collet holder with a 3MT on my mill. Also use it on my lathe as it also has a 3MT taper in the spindle. My rotary table is also 3MT which allows me to keep the job in the collet holder and transfer to another machine without losing its centre position.

Paul

Edited By Paul Lousick on 17/03/2021 04:12:03
17 March 2021 at 07:19 #534305
not done it yet
Participant
@notdoneityet
You have to get a backplate to match your lathe and attach the collet chuck to it.

Better to say ‘that’ collet chuck. I use an ER 32 collet chuck, from Arc, on my lathe.

It is easily mounted on a backplate and offers the advantage (over those with drawbars) of being able to accommodate long pieces which can fit down the lathe spindle (so can be machined with minimal stick-out from the collet).

Backplates are available for some lathes but are not difficult to make, if they are not.
17 March 2021 at 07:19 #534306
JasonB
Moderator
@jasonb
Have a word with Chester, although not on their website their paper catalogue lists various threaded backplated for the 920. Once screwed onto the lathe spindle these are finish turned to suit your chuck recess and fixings.

Warco's 918 backplates may well also fit

Edited By JasonB on 17/03/2021 07:34:15
17 March 2021 at 10:14 #534331
Andrew Tinsley
Participant
@andrewtinsley63637
Might be worthwhile to check the spindle thread. 920 lathes have either a metric spindle thread or an imperial one. Don't ask how I know.

Andrew.
17 March 2021 at 11:51 #534343
Howard Lewis
Participant
@howardlewis46836
If it is any help, Amadeal quote the thread for a Faceplate as 39 x 4.

But remember the warning by Andrew Tinsley that your Mandrel might have an Imperial rather than Metric thread.

PURE GUESSWORK If the thread were 1 1/2 x 8 tpi that would sound like a Boxford fit.

If so Arc Euro offer Backplates in Boxford fit, which could be machined to take one of their ER collet chucks.

Amadeal only seem to quote collet chucks with MT taper shanks rather than with Backplates.

HTH

Howard
17 March 2021 at 12:04 #534346
Vic
Participant
@vic
Whatever you do Erik, don’t be put off. I’ve found the ER32 collet Chuck I bought for my lathe invaluable. The collets also get used on my Milling machine and WW lathe as well as a spindexer and collet blocks.
17 March 2021 at 12:07 #534347
Bo’sun
Participant
@bosun58570
In response to Howard's comment regarding Amadeal. I had to send two MT4 ER32 collet holders back to Amadeal because the M16 drawbar threads were misaligned (at an angle) with the centreline.
17 March 2021 at 12:23 #534349
Howard Lewis
Participant
@howardlewis46836
It may be that the eventual solution would be to buy a plain backplate, cut a thread to suit your lathe, screw it onto the Mandrel, face, and turn the OD to suit one of Arc Euro's Collet chucks.

If this is your chosen route, I would be inclined to have the Collet chuck to hand, before machining the register, so that the Backplate can be as tight a fit as possible to the Collet chuck.

They range in OD from 60 mm through to 125 mm depending on what size ER collet system you choose.

The register varies between 43 mm and 95 mm over the same range.

It would be worth looking at their website, which gives OD, register diameter and depth.

Collets and spanner will be extra.

HTH

Howard
17 March 2021 at 22:26 #534478
Pete.
Participant
@pete-2
Just be aware, if you have an imperial spindle which I have on mine and you buy the Boxford backplate from Arc, the backplate is actually about 1/4 too thin for the spindle, the nose of the spindle will stick out, I just bored the rear of the vertex 4 jaw I was fitting, and it actually worked out better, as the chuck sat nearer the headstock.

But this might not be possible with a collet chuck.
18 March 2021 at 07:10 #534505
JasonB
Moderator
@jasonb
Don't think a 920 will cut 4mm pitch or similar imperial pitch so making your own could be a problem. Both the suppliers I suggested list metric and imperial backplates.
18 March 2021 at 10:33 #534564
Howard Lewis
Participant
@howardlewis46836
My lathe isn't a 920, so this may not be possible,. In theory the coarsest pitch that I can cut is 3 mm but by using one of the other other small changewheels, (40T instead of 30T ) it was possible to set the Norton box to cut a 4 mm pitch thread. I used back gear for this

Howard

Edited By Howard Lewis on 18/03/2021 10:34:01
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