Collet Chuck for my CL250M?

Hi Ian,

It is a straight fit (possibly tight) onto the chuck flange/back plate (Part 45) on this diagram

You will need a rubber mallet, to remove/fit the chucks.

Fixing studs are not supplied. 3 x Fixing holes are tapped M6 as shown in the details table on this page

Basically, the general 'Chinese Standard' for the back female register on an 80mm 3-Jaw Self-Centring (S.C.) Chuck is 55mm - to enable it to fit onto a flange/backplate with the matching 55mm male register. Also, most such chucks are tapped M6.

So, the ER lathe collet chuck registers and PCDs are made to conform to the Chinese standards of 80mm, 100mm, 125mm lathe chucks.

You may be able to unscrew the studs from your standard 3-Jaw S.C. Chuck and use them with your ER 25 lathe collet chuck. As far as I can recall, the studs would be introduced from the back of the flange, and screwed into the body of the ER25 lathe collet chuck, in the same way as your existing arrangement with the 3-Jaw S.C. chuck. Note: the stud does not need to go all the way through the tapped hole, as long as the studs go in a reasonable amount to hold the collet chuck secure in place, and you feel comfortable. Alternatively, you make up your own arrangement with studs and nuts to meet your needs.

Ketan at ARC

Edited By Ketan Swali on 25/02/2021 11:44:38

Swapping the studs between chucks is daft. I loctited short lengths of studding in all of mine that didn't come with the lathe. I did the same with the mini-lathe when I had it.

For my 3J, 4J, and Collet chucks, I cut M6 studding to a suitable length and loctited into each chuck..

To save having to look for dropped nuts all the time, (Not enough room for my fingers between Flange and Headstock ) I made up a "Widget" as per the article by Danny M2Z, in MEW. Have only dropped one nut since, so what little time it took to make (Minutes ) was well spent. Recommended!

Howard

I would be most keen to know more about Danny's widget (even the Howard version). Dropping nuts as I attach a chuck is a kind of hobby of mine. One I'd like to drop!

Iain

Danny M2Z's Widget was fearured in an short article in MEW some time ago.

SO simple, why didn't someone think of that a long time ago?

A simple and very useful tool.

Without wanting to steal Danny's thunder.

It was apiece of banding strip, in my case, about 18 -20 mm wide and 2 mm thick.

With shears, make two cuts, 6mm apart, equally spaced about the centre line, and about 25 - 30 mm long..

Bend up about 5 mm of the central "tongue" at 90 degrees, and file a chamfer on each side so that the tongue has the makings of a flat arrow point.

To remove the nut start to slacken the nut, and when there is clearance, slide the Widget behind the nut so that the central tongue will engage in the nut as it unscrews, There will be room to operate a 10 mm spanner.

When the nuts comes off the stud, the central tongue will press it against the outer flats, so that it does not fall.

Remove nut from Widget and put in a safe place. Repeat on the other nuts. The chuck may become loose as the final nut is loosened.

As Haynes manuals say "Reassembly is merely the reverse of the foregoing"

The Widget will hold the nut in place as it starts on the thread. Once started, since the nut is no longer likely to fall, the Widget can be removed. (Once the outer side of the nut coincides with the end of the stud, the Widget no longer holds the nut. and can be withdrawn, before the nut begins to clamp the Widget to the Flange.

All credit to Danny for inventing and publicising it!

Howard. typos corrected 

Edited By Howard Lewis on 25/02/2021 18:40:35

Well, bit the bullet this morning and placed an order with ARC for the ER25 collet chuck along with a few other bits and bobs to make the order up to £75. Two of which will allow me to fabricate a 10mm bore 36 tooth change wheel to make the switching between 1 and 1.25mm pitch on the leadscrew easier

Delivery from ARC today, will hopefully fit the chuck to my lathe this evening, just got the m6 studs to fabricate and loctite in place

In his book, "Gearing of lathes for Screwcutting" Brian Wood lists many changewheel set ups for the mini lathe, which may be applicable to your C1..

For a machine with a 1.5 mm Leadscrew, to cut a 1.25 mm pitch thread, he advises using Driver 50T, Idler, Leadscrew 60T . The Manual for my C3 advises a 40T as the Idler.

1.5 x 5 / 6 = 1.25.

So there should be need for a 36T changewheel

If your lathe has a 16 tpi Leadscrew, the Changewheel set up would be:

63T driver, 40T on Stud B, 30T on Stud C and 60T on the Leadscrew.

A C1 may not be the same as a C3.

The C3 changewheels supplied should be: 20T x 2, 30T 35T, 40T x 2, 45T, 50T, 55T, 57T, 60T, 65T and 80T x 2

It might be an ideas to splash out and buy Brian's book,since, in addition to providing a lot of history, details of various lathes, there are tables specifically for mini lathes, with eiether b16 tpi or 1.5 mm pitch Leadscrews..

For a 1.5 mm pitch Leadscrew, one table covers pitches from 0.2 mm upto 3 mm, and another table covers changewheel set ups for Imperial threads from 8 tpi to 80 tpi, as well 17 as and 23 tpi Another table covers BA threads.

If you do not have a manual for your C1, ARC may be able to supply one .

It may be possible to download one for a Clarke CL250M, and the parts list, as pdf from Google. Just nentre "Clarke CL250M" and you may find one heading for the manual, and another for the parts list and wiring diagram.

Howard

One other thought.

If you are going to screwcut on a small lathe, in view of the low power motor, I would make up a Mandrel Handle to use instead of the motor.

The motor will not like a large load at low speeds where little air flow will be available for cooling.

Also, manual power greatly reduces the risk of you damaging / breaking Taps, Dies or Tools when working up to a shoulder.

If you are relatively inexperienced, making a handle will also be a useful learning exercise for you to gain experience and become more familiar with the machine, since in addition to turning it will involve Drilling, Tapping, Using a Die and turning a couple of tapers.. Plus a bit of handwork.

You will also gain experience in measuring.

Howard

Edited By Howard Lewis on 01/03/2021 17:31:13

I would make up a Mandrel Handle to use instead of the motor.

I would recommend a wheel rather than a handle - for safety reasons.

Fits like a glove