Turning between centres on a Cowells CW lathes

[Nigel WattsParticipant @nigelwatts49512]

I would like to be able to turn between centres in my Cowells CW lathe but I can't work out how to do it as the faceplate can't be fitted as well as a centre. The only thing I have come up with is a specialist carrier which is fitted like a collet. Cowells don't supply one but they can be bought at a price from Bergeron. Any ideas?

[Nigel WattsParticipant @nigelwatts49512]

[Michael GilliganParticipant @michaelgilligan61133]

You could go 'back to basics' and try turning between dead centres, with a bow

But may I suggest that, for inspiration, you look at the driving plate mentioned here: **LINK**

https://watchmaking.weebly.com/other-lathe-attachments.html

… incidentally, that ^^^ is an extensive, and remarkably good site.

MichaelG.

[peak4Participant @peak4]

If you have a chuck, use that to hold a bit of scrap bar and turn it down to a point; there's your nice new guaranteed true dead centre. Maybe even use a square bar in a 4 jaw and turn a parallel section behind the point so you can clock it for re-use.
Drive the workpiece with a right angled carrier/dog off one of the jaws.

Bill

[John ReeseParticipant @johnreese12848]

Posted by peak4 on 27/05/2019 22:14:18:

If you have a chuck, use that to hold a bit of scrap bar and turn it down to a point; there's your nice new guaranteed true dead centre. Maybe even use a square bar in a 4 jaw and turn a parallel section behind the point so you can clock it for re-use.
Drive the workpiece with a right angled carrier/dog off one of the jaws.

Bill

That is exactly what I do on my lathes.

[HopperParticipant @hopper]

Using the chuck as mentioned above has the advantage too of placing the centre to the right hand end of the gap in the bed. So you don't have to wind the carriage half off the bed ways to turn the far left hand end of the job between centres. A centre straight in the spindle is actually fairly useless on most gap bed lathes.

Here's a couple pics of a simple drive dog for use with the centre in the chuck that I made up from some scrap aluminium flat bar, about 12mm x 50mm or so.

 

Edited By Hopper on 28/05/2019 06:01:36

[JasonBModerator @jasonb]

Same as above, a cranked driving dog located easily against a chuck jaw.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 28/05/2019 05:46:02:

Using the chuck as mentioned above has the advantage too of placing the centre to the right hand end of the gap in the bed. So you don't have to wind the carriage half off the bed ways to turn the far left hand end of the job between centres. A centre straight in the spindle is actually fairly useless on most gap bed lathes.

.

True … but have you looked at a Cowells CW ?

MichaelG.

[HopperParticipant @hopper]

Only pics. They are thin on the ground around here. Probably all got used as stock feed during the war. Seems to have a gap. But toolpost well forward of the carriage, which is less than ideal. But hey, whatever works.

[Michael GilliganParticipant @michaelgilligan61133]

The main difficulty, for the work that Nigel is doing [likely to involve use of a graver], probably relates to the 'human interface' rather than the risk of winding the carriage half off the bed ways.

It's quite a small machine; and a clean & compact drive arrangement for between centres work gives more clearance for hands, and better sight-lines.

MichaelG.

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http://www.cowells.com/docs/90cw.pdf

https://watchmaking.weebly.com/cowells-90cw.html

Edited By Michael Gilligan on 28/05/2019 09:10:05

Edited By Michael Gilligan on 28/05/2019 09:19:00

Edited By Michael Gilligan on 28/05/2019 09:21:37

[Nigel WattsParticipant @nigelwatts49512]

Lots of great ideas, as ever – Thank you.

The Cowells CW is a bit of hybrid between a watchmakers' and a regular lathe. The headstock and tailstock are both set up for use with 8mm watchmakers' collets and both have a drawbar. Unlike a watchmaker's lathe however there is a big gap in the lathe bed to accommodate larger chucks and bigger diameter work. These chucks screw onto an adapter which in turn is fitted to the headstock with three bolts, meaning that a centre cannot be fitted at the same time.

As Michael says, I am hoping to user a graver for the work when turning between centres so the gap should not be an issue so long as I can position the handrest securely over the gap. Holding some bar in a chuck and turning it to a point is a good idea. It will need to be trued up again each time it is used I guess, but this should not be too onerous. I will need to acquire or make a suitable lathe dog however.

A watchmaker would probably use one of these, but they are not cheap:

 

 

Edited By Nigel Watts on 28/05/2019 12:57:47

[Roderick JenkinsParticipant @roderickjenkins93242]

Not difficult to make from an 8mm blank end arbor from RDG **LINK**

Rod

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Roderick Jenkins on 28/05/2019 13:21:39:

Not difficult to make from an 8mm blank end arbor from RDG **LINK**

Rod

.

… and it could end up looking remarkably like the one that I mentioned in my first response

MichaelG.

.

[quote]

But may I suggest that, for inspiration, you look at the driving plate mentioned here: **LINK**

https://watchmaking.weebly.com/other-lathe-attachments.html

[/quote]

[Nigel WattsParticipant @nigelwatts49512]

Thanks Rod – I have used blank 2 MTs from RDG to make wheel mandrels but I wasn't aware you could get 8mm collet style blanks too. The only thing it doesn't seem to have, based on the picture, is the pair of keyways on the shank but I guess these are not essential. Ordering one now!

[Nigel WattsParticipant @nigelwatts49512]

Thinking about it, without the keyways it probably won't fit into the headstock. I guess I could anneal it and put some in?

[Author]

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