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To ER is human but ER collets could be divine

Fitting ER collets to a Sherline lathe spindle

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Stuart Munro 119/06/2021 11:15:33
108 forum posts

Thanks to much help on a previous topic, I've decided to investigate purchasing a set of ER collets for my Sherline lathe.

Sherline make a specific spindle to take ER 16 collets but to us this I would have to strip out the MT1 spindle and replace or adjust all of my other fittings.

RGD tools are offering a competitive (cheap!) set of 10 ER 16 collets with an MT1 taper. Am I right to assume that I could simply fir the collets to my Sherline (MT1 spindle). Seems too simple a solution.


Stuart Munro 119/06/2021 11:17:16
108 forum posts

Sorry, not clear - the RGD set includes a MT1 taper, drawbar and ER 'nut' plus the 10 ER collets - all for about £60!

Vic19/06/2021 11:24:56
2920 forum posts
8 photos

Direct fit collet chucks normally allow you to pass stock right through the head stock which can be very handy. Morse taper shanked chucks work fine but should be secured with a draw bolt.

Stuart Munro 119/06/2021 11:32:15
108 forum posts

So my only real drawback is not being able to pass stock through, Thanks Vic. Looks like £60 well spent even it I cant use the collets in every situation.


John Haine19/06/2021 11:33:32
4188 forum posts
242 photos

RDG not RGD.

Ideally you would have an ER16 chuck that screws on to the 3/4" thread on the headstock - something like this one from Taig:


Others are available.

That way you spend a lot less ($30 plays $200 at US prices), can carry on using all your MT1 tooling, and pass longer stock through the chuck into the spindle.

MT to ER chucks are really for milling.

John Haine19/06/2021 11:58:29
4188 forum posts
242 photos

OR you could buy a backplate to fit:

and an ER16 chuck:

You would have to machine the register on the backplate to match the chuck in-situ on the spindle.

Stuart Munro 119/06/2021 12:11:13
108 forum posts


Thanks - the ARC Euro ER 16 chuck looks interesting. I already have n unused backplate that came with my lathe so its just a case of machining it to accept the ER chuck. Great idea and even cheaper than the RDG set.

I confess to being a bit unsure about 'cheap' sets anyway. Not sure of the quality although other things bought from RDG have been fine.


KWIL19/06/2021 12:16:39
3425 forum posts
66 photos

Things bought from Arc Euro will also be fine, good supportive supplier.

duncan webster19/06/2021 12:16:44
3526 forum posts
63 photos

I know this is a wild goose chase, but my very early Cowells has M14*1.5 spindle nose. Anyone got any idea where I'd buy an adaptor like the one John Haine linked? I could make a new spindle, but then existing chucks etc wouldn't fit. I don't anticipate working up the energy to make an adaptor any time soon.

Howard Lewis19/06/2021 14:23:23
5348 forum posts
13 photos

Hi Duncan,

Pity, about the 1.5 mm pitch. Arc Euro do 14 x 1 backplates for Cowells /Unimat

Looks like you are in Catch 22, needing a means of holding a backplate blank, over 62 mm daimeter, so that you can bore and screwcut for the 14 mm spindle thread and register

Having bought a ER chuck on a backplate, with collets and a spanner, you are ready to "personalise" your backplate.the

As you know, your backplate is reversed to be faced and the OD turned to match that of the collet chuck, before spotting through the ER backplate to drill and tap for the fixings

It would be too much to hope that the actual ER 16 backplate would be soft enough to be bored to 12.5 mm, and screwcut to save space. Presumably clamped on to a bar set to run true in a 4 jaw


DC31k19/06/2021 18:13:50
578 forum posts
1 photos

Please look up Axminster Junior chuck.

ER20, will fit Taig spindle at 3/4-16 so should also fit Sherline.

In the past, Axminster would make you an adaptor for this chuck, so if this service is still offered, the M14 x 1.5 might be possible.

Nigel Graham 219/06/2021 23:35:27
1712 forum posts
20 photos

If you need make a backplate, M14 X 1 and 1.5mm taps are available.

Stuart Munro 120/06/2021 07:41:55
108 forum posts

Thanks guys - I can now see that the ARC Euro combination of Taig backplate and ER16 collet chuck are designed to fit each other. And s DC31K says, the Taig uses the same thread as Shirline - my problem solved at around £35.

Plus a selection of ER Collets!


John Haine20/06/2021 07:58:35
4188 forum posts
242 photos

I think you'll find that you still have to turn the register on the backplate to fit - I certainly did on my Unimat.

Stuart Munro 120/06/2021 11:42:57
108 forum posts


As a life long office worker I'm still quite new to this engineering stuff so please excuse me asking something that is probably blindingly obvious.

The ARC Euro Taig Backplate comes in 3 varieties; blanc, 4 point fix and 2X3 point fix (making 6 holes in a circle).

The ER 16 Lathe Chuck Collet has a 43mm register diameter, 5mm register depth, and a 'PCD' of 51.5mm.

The 2X3 point fixing Taig Backplate has a 44mm register diameter but looks to have compatible fixing hole positions and sizes. (PCD of 51.5mm, 5.5mm clearance holes leading to 0.8mm depth on M5 thread)

So presumably the 'registering' is facing the backplate so that it is smooth. If that's the operation you refer to then it should be no problem but the ARC Euro site and your observation make me think there is more to this that I think.

Is that so?


Stuart Munro 120/06/2021 11:58:00
108 forum posts

Ah - found a MEW article from 2008 where it has become obvious that the chuck must sit on the backplate perfectly perpendicular to the axis and of course, the fixing holes need to be precisely positioned. But is the 3 fixing holes are already made then a 'facing' operation carried out on the lathe should leave the backplate face perpendicular to its axis.

The article talks about the middle of the backplate being recessed so that the chuck sits only on a circle where the fixing bolts are. Or am I reading this wrongly?


John Haine20/06/2021 12:12:33
4188 forum posts
242 photos

The back of the chuck is recessed and the periphery of the recess should be concentric to the chuck. There needs to be a "spigot" on the backplate, that is a "raised" portion from the centre to a radius that fits snugly into the recess, to centre the chuck on the backplate. I think there is probably already a spigot machined but the diameter will be too large.

The idea is to fit the backplate to your lathe, turn the spigot to the exact diameter to fit the chuck and also face the outer "flange" (the bit where the mounting holes are) so it is perpendicular to the spindle axis. The spigot "height" should be slightly less than the depth of the recess. The mounting holes will have a clearance so the chuck position is fixed by the spigot and the outer flange, you can't rely on them to centre the chuck. It's a slightly tricky job but good practice!

Stuart Munro 120/06/2021 13:20:46
108 forum posts


That all makes sense - you should re-write the article for MEW. The original is good but assumes more than a basic knowledge such as mine!


Stuart Munro 120/06/2021 13:24:31
108 forum posts

ps - So if I got my hands on a Taig ER16 collet holder - which threads onto a 3/4 16 Sherline thread - I would not even need to register it.

But as you point out - Registering would be good practice....


Peter Cook 620/06/2021 13:37:01
166 forum posts
50 photos

Try Peatol (Peatol Machine Tools). Currently offering the Taig ER16 adapter P/N 1045ER for £42.00 plus £4.00 post and packing. The price list was updated on the 18th May this year.

I haven't used them - I got my lathe ( with the native ER spindle) direct from Taig in the US - they are very helpful but carriage can kill you.

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