Collet chuck for lathe

Includes workshop practice, painting and weathering, model photography etc.
User avatar
David B
Posts: 1185
Joined: Sun Jul 20, 2008 5:30 pm

Collet chuck for lathe

Postby David B » Wed Apr 29, 2020 11:29 am

I am looking for and struggling to find, a collet chuck for small collets which I think are ER10. I have a morse taper chuck they fit for a milling machine but want one for my lathe. The collets I have go from 1mm to 7mm.

Can anyone where I might get a chuck (I can't find one on the web) or will I have to buy a new set of larger collets to go with a larger chuck?

Advice will be welcome.

User avatar
Wizard of the Moor
Posts: 164
Joined: Mon Jul 21, 2008 9:02 pm

Re: Collet chuck for lathe

Postby Wizard of the Moor » Wed Apr 29, 2020 12:04 pm

It's probably an ER11 collet set, rather than ER10. Something like this might do if you can find or make a suitable adapter.

https://www.arceurotrade.co.uk/Catalogu ... kJT1-Taper

James

nigelcliffe
Posts: 538
Joined: Mon Jul 21, 2008 8:31 am

Re: Collet chuck for lathe

Postby nigelcliffe » Wed Apr 29, 2020 12:37 pm

Other suppliers will have ER collet holders in straight shanks, such as APT
https://www.shop-apt.co.uk/

I agree the collets up to 7mm are likely to be ER11.

It may be easier to make an adaptor to the lathe using a straight shank holder than a JST taper, depends how easy it is to setup the lathe for accurate taper turning.
What is the lathe in question ? And roughly what tooling is available ? That might help answer how hard it will be to make the adaptor fit.

With ER collets being fairly cheap, having different types on different machines may not be that much of a burden. I think the smaller common ER collets are ER8, ER11 and ER16. ER8 are really tiny (I have some which came with a milling machine). ER11 and ER16 are my normal sizes.


- Nigel

User avatar
45609
Posts: 164
Joined: Mon Jul 21, 2008 10:28 am

Re: Collet chuck for lathe

Postby 45609 » Wed Apr 29, 2020 12:48 pm

Hi David,

What size Morse taper do you have in your lathe headstock spindle? MT2 and MT3 is common on middle size hobbyist lathes (e.g. Myford series 10 and 7, Warco, Chester, etc...) MT1 and MT0 is smaller and less common but found on things like Sherline and Cowells lathes.

You can buy a ready made ER11 to MT2 collet chuck and collets like the link below. Possible that MT3 or MT1 is also available but I haven't looked.

https://www.amazon.co.uk/Extension-craftsman168-Engraving-Machine-Milling/dp/B07S86TJ8D

The other option is make your own on the lathe using a "soft" MT blank of the appropriate size.

https://www.rdgtools.co.uk/cgi-bin/sh000001.pl?WD=blank%20mt2&PN=2%2dMORSE%2dTAPER%2dBLANK%2dEND%2dARBOUR%2d10%2dMM%2dDRAWBAR%2dTHREAD%2d12233A1%2ehtml#SID=496

Of course this depends on your machining confidence but, if up for a challenge, then why not? MT blanks are quite cheap. If you do go that route make sure you get a blank that has a drawbar thread in the back to hold the taper into the headstock socket.

Other things you'll need are,
    An ER11 collet nut but these are freely available to buy as separate items
    The ER11 specification to be able to machine the socket and OD thread for the nut (picture below and pdf document)
    An M14 x 0.75 die to form the male thread for your nut
    Drills, centre drill, 5mm drill (roughing) and 7.5mm drill (finishing)
    Left hand turning tool and boring bar

ER collet dims.png


The one advantage of trying to make your own is that it will be accurate because you're machining it in situ.

Cheers...Morgan
Attachments
ER collet data.pdf
(180.18 KiB) Downloaded 10 times
Last edited by 45609 on Wed Apr 29, 2020 2:44 pm, edited 1 time in total.

User avatar
45609
Posts: 164
Joined: Mon Jul 21, 2008 10:28 am

Re: Collet chuck for lathe

Postby 45609 » Wed Apr 29, 2020 1:01 pm

I should have also said that you'll need some sort of feature on the ER shank to enable tightening of the collet nut. Flats aren't the easiest thing to get right but you did say you had a milling machine. The other option is drill a couple of equal depth blind holes 180 degrees apart (i.e. opposite each other) to fit a tommy bar. You need two otherwise the chuck will be out of balance and very inaccurate due to vibration. Below is a picture of an ER11 chuck I made to fit the drilling head on my Stevens Mill.

Stevens mill ER11 chuck.jpg


cheers...Morgan

nigelcliffe
Posts: 538
Joined: Mon Jul 21, 2008 8:31 am

Re: Collet chuck for lathe

Postby nigelcliffe » Wed Apr 29, 2020 2:35 pm

45609 wrote:Hi David,

What size Morse taper do you have in your lathe headstock spindle? MT2 and MT3 is common on middle size hobbyist lathes (e.g. Myford series 10 and 7, Warco, Chester, etc...) MT1 is smaller and less common but found on things like Cowells and Sherline lathes.



Cowell is MT0 - I have a Cowell.

Nigel

User avatar
45609
Posts: 164
Joined: Mon Jul 21, 2008 10:28 am

Re: Collet chuck for lathe

Postby 45609 » Wed Apr 29, 2020 2:46 pm

Thanks for the correction Nigel. My mistake. I've amended my post above.

Cheers...Morgan (doesn't have a Cowell)

User avatar
David B
Posts: 1185
Joined: Sun Jul 20, 2008 5:30 pm

Re: Collet chuck for lathe

Postby David B » Wed Apr 29, 2020 4:12 pm

Thanks, chaps. There is a lot to digest as I am completely inexperienced in this field. I do the odd thing here and there, having avoided doing myself any injury thus far, but have no real experience with these tools. I never had lessons in either wood or metal work at school, in fact there was no metalwork shop and a woodworking shop was only set up in my last year in the 6th form.

The lathe is a Ross and Alexander I bought from Terry Bendall a few years ago. I don't think the headstock will take a taper.

Stephan.wintner
Posts: 8
Joined: Sun Mar 15, 2020 11:04 pm

Re: Collet chuck for lathe

Postby Stephan.wintner » Wed Apr 29, 2020 4:53 pm

Curiousity led me to google - this link suggests an MT1 taper for the RandA

http://www.lathes.co.uk/randa/

Stephan

User avatar
45609
Posts: 164
Joined: Mon Jul 21, 2008 10:28 am

Re: Collet chuck for lathe

Postby 45609 » Wed Apr 29, 2020 5:12 pm

Hi David,

I'm not sure about the RandA lathe headstock either. A look here might tell you a bit about what you have if you weren't aware of the website "lathes.co.uk"

http://www.lathes.co.uk/randa/

I would be surprised if there wasn't some form of morse taper in the headstock bore. Looking at some of the RandA photos on the above page there is definitely a taper in the tailstock bore. There is mention in the write up about the RandA having a No.1 morse taper (MT1) in the head and tailstock. I'd take the chuck off and have a look. Maybe then offer up the drill chuck or dead centre to the headstock bore and see if it seats positively? If it does then you're in business.

Believe it or not I've had no formal training in turning or milling either but I have worked in engineering all of my life. My earlier career (only 18 months or so, a very long time ago) was on cylindrical grinding and honing machines. My turning and milling is self taught with a copious application of common sense.

Cheers...Morgan

nigelcliffe
Posts: 538
Joined: Mon Jul 21, 2008 8:31 am

Re: Collet chuck for lathe

Postby nigelcliffe » Thu Apr 30, 2020 9:58 am

Unless its also fitted with a draw-bar to hold in place, I would be reluctant to use a MT-1 taper to hold a chuck in place, its likely to shake loose. Making a draw bar with a nut on the end shouldn't be difficult.

What's the chuck nose fitting on the lathe ? Can you make a new nose fitting (chuck backplate) using the screw cutting on the lathe ? It would need appropriate faces to seat against the nose, along with relieving a few corners so it definitely sits on a flat, not a corner.
With a new backplate, a suitable piece of round is fitted to the backplate, and bored to take the ER collet holder. Because its bored on the machine, it is as accurate as the operator of the machine, so should be very concentric. Fit the tool holder into that.

User avatar
David B
Posts: 1185
Joined: Sun Jul 20, 2008 5:30 pm

Re: Collet chuck for lathe

Postby David B » Thu Apr 30, 2020 10:25 am

There is a hole through the headstock which is 12.6mm at the chuck end and 7.7mm at the other. However, 25mm in, there is a step, so if there is a taper, it is only over that distance.

Is this the chuck nose fitting you refer to, Nigel? I am afraid thread cutting is beyond my skill - something to learn.

headstock_c3677.jpg

John Palmer
Posts: 609
Joined: Fri Jul 15, 2011 11:09 pm

Re: Collet chuck for lathe

Postby John Palmer » Thu Apr 30, 2020 12:19 pm

The picture David has posted suggests to me that this lathe may be an example of Brian Perris' Pixi/Jason design re-worked by Ross and Alexander to offer a 2" centre height (see http://www.lathes.co.uk/jason/) and known as the 'New RandA. According to the linked page, "the very early headstock spindle had a simple No. 1 Morse taper, but this was quickly changed to a special fitting intended to accept a compression collet with the centre carried (in the usual way) on a solid collet." "Special fitting" suggests a proprietary design, which unfortunately may mean making your own. The thread forming part of the exercise doesn't have to be accomplished by screwcutting on the lathe provided a suitable die is available for the purpose.

nigelcliffe
Posts: 538
Joined: Mon Jul 21, 2008 8:31 am

Re: Collet chuck for lathe

Postby nigelcliffe » Thu Apr 30, 2020 12:45 pm

David B wrote:There is a hole through the headstock which is 12.6mm at the chuck end and 7.7mm at the other. However, 25mm in, there is a step, so if there is a taper, it is only over that distance.

Is this the chuck nose fitting you refer to, Nigel? I am afraid thread cutting is beyond my skill - something to learn.


Threadcutting is a matter of setting up the gearwheels (assuming you have them) to drive the lead screw at the right rate to cut the thread. Most lathes have tables to work it out. Or its simple ratios in a spreadsheet.
But, threadcutting an inside (female) thread is a bit harder than outside, as it needs a suitable tool, like a boring bar with a thread shape.
So, if going to learn, start with a male thread for practise.


When I've cut threads on the Cowell, I've usually cut them slightly to one side by advancing the top slide a tiny bit. Thus not trying to cut both faces of the V of a thread at one go, then for the next pass back the top slide a little to cut the other side of the V.

You may be able to find out the size, and purchase a tap to cut the thread in a home made backplate. But, its a fairly big one, so might be too much for home use ? A small engineering works might be able to make up backplates needed for you.


Looking at that headstock spindle, there is a flat area, and a cylindrical part, then a reduction in diameter before the thread starts. The flat area and the cylinder are the key registration surfaces for any chuck or backplate. The cylinder sets the cylindrical reference (concentricity). Any backplate made at home needs accurate dimensions against that cylinder, and will also need a relieving bevel to not bottom at the join from flat to cylinder. (Hope that makes sense !).



- Nigel

Terry Bendall
Posts: 1726
Joined: Sun Jul 27, 2008 7:46 am

Re: Collet chuck for lathe

Postby Terry Bendall » Fri May 01, 2020 4:13 pm

David B wrote: I am afraid thread cutting is beyond my skill - something to learn.


It may well be David but it probably counts as an A Level job.! :)

nigelcliffe wrote:When I've cut threads on the Cowell, I've usually cut them slightly to one side by advancing the top slide a tiny bit.


The usual method is to angle the top or compound slide of the lathe to half the thread angle. This will vary depending on which thread it is. British Standard Whitworth threads have a thread angle of 55 degrees as does the BS Fine thread. Using the top slide to advance the tool means that it will cut on the leading edge although the method Nigel describes is a way of solving the problems for those without a top slide that can be turned at an angle. However you have to be careful since the pitch of the thread may not be correct along the length of the thread. Another dodge is to rough out the thread on the lathe and then finish it with a die. A reference book on lathe work for the model engineer will give all the details needed.
One which I like and still refer to on occasions is "The Amateur's Lathe" by L.H. Sparey ISBN: 0-85242-288-1 Published by Special Interest Model Books. This was first published in 1947 so may be thought a little dated in style today but the technical information does not change.

To measure a thread you need to know the outside diameter and the pitch which is the distance from the top of one thread to the next or alternatively the distance a nut moves when rotated one turn. All will be revealed in the next part of my Starting from Scratch series which will cover making and using screw threads.

In my view cutting of screw threads on the lathe is not a job for those with limited experience and is not needed for our scale of modelling. If you can measure the size if the thread on the spindle nose a jobbing engineering company, if you can find one, should be able to make what is needed or look to see what is available from model engineering suppliers. Alternatively make friends with someone whom is into model engineering and who may have the skills. :)

Once a backplate is roughed out and fitted to the spindle of the lathe on which it is to be used, it should be finished to size on the machine. That way it should be concentric.

Terry Bendall

nigelcliffe
Posts: 538
Joined: Mon Jul 21, 2008 8:31 am

Re: Collet chuck for lathe

Postby nigelcliffe » Fri May 01, 2020 5:25 pm

If David B is in the N-Essex/S.Suffok area of his layout, then I could point him at a "jobbing engineering company" who could make backplates if given a clear specification drawing showing key diameters, dimensions and thread size. I understand they're going back to limited work either today, or Monday. Could probably do the entire transaction by email and post if the drawings are clear.

- Nigel

User avatar
David B
Posts: 1185
Joined: Sun Jul 20, 2008 5:30 pm

Re: Collet chuck for lathe

Postby David B » Fri May 01, 2020 6:17 pm

Thanks for the thought, Nigel, but I am a couple of hundred miles away in Devon. I have a cunning plan to follow up.


Return to “Tools and Techniques”

Who is online

Users browsing this forum: No registered users and 2 guests