Cromwell lathe

[WestburyParticipant @westbury]

Hi to all, this is my first post on the site, and I am asking for advice on adjusting the headstock spindle tapers on a Cromwell 3.5" SS & SC Lathe type S 800. This lathe is new to me and I am just setting about refurbishing it. The front and rear 'thrust caps' ( description according to manual) appear to have ridges for C spanner use, and I see there is a pin which goes through side of the cap. I am not sure of the purpose of this pin. At the moment I can 'rattle' these caps by hand, but cannot unscrew them by hand. There is no apparent end or side play in the spindle.

I cannot see that it is normal that these caps should be loose, and yet there is no apparent way (other than using the C spanner? ) to tighten them. I assume this will also tighten (maybe overtighten) the tapers.

Before I launch right in, I thought I would ask if anyone has experience with this lathe and its adjustment.

Any advice appreciated.

Paul

[WestburyParticipant @westbury]

Headstock adjustment

[Neil WyattModerator @neilwyatt]

Hi Paul,

Looks a rather nice wee lathe!

Have you looked on the Lathes.co.uk website?

It says "A data pack for the Cromwell with
Instruction Book, Parts Book and Catalogue Collection is available".

Neil

[Phil WhitleyParticipant @philwhitley94135]

Oh yes that does look nice, you lucky man! We would all love to see some photos of your lathe and the rebuild, and it is easier to answer questions when we have "summat to look at"

Good luck with it!

Phil

[WestburyParticipant @westbury]

Hi Neil and Phil, and thanks for your replies. The Cromwell needs work, but it has some very interesting features. I did get the data pack from Tony Griffiths and this has been a great help. No doubt all will become clear once I start dissassembly. I will try and post some pics as I go. Neil, did anyone contribute with a Cromwell for your 'One man and his lathe feature' ?

Paul

[Neil WyattModerator @neilwyatt]

> did anyone contribute with a Cromwell for your 'One man and his lathe feature' ?

Not yet! Why not write it up once you have it up and running?

Neil

[Mark Chapman 1Participant @markchapman1]

Takes a while for the bearings to warm up and tighten up!

Do not tighten cold is my advice – Not sure thats in the manual

Mark

[CHRISTOPHER MILLS 1Participant @christophermills1]

Dear Westbury,

How are you getting on with your Cromwell S800 restoration?

I have an earlier Cromwell Smallpeice MkII screw-cutting lathe.

Cromwell Smallpeice build quality was virtually unsurpassed in English lathe manufacture, likely why the company was in existence for only a short time.

Nobody could afford their wares, 1940s and '50s. That sort of quality did not come cheaply.

Best wishes

Chris Mills

[Mike PooleParticipant @mikepoole82104]

Interesting that they had Ward Leonard speed control on a small machine, must have been a significant component of the high price of the lathe. Strangely the thought of building a Ward Leonard control went through my mind a few days ago but compared to a flux vector inverter it would cost a lot. I have worked on a number of machine tool control systems that used Ward Leonard speed control, one was a big Stirk planer and a couple of Droop and Rein NC milling machines.

Do the lathes mentioned in the thread still have their WL control?

Mike

[duncan webster 1Participant @duncanwebster1]

A good trick with the Ward leonard if the 3 phase motor/generator is U/S is to use thyristor drive to power the DC motor

[CHRISTOPHER MILLS 1Participant @christophermills1]

My Cromwell Mk II screw-cutter has a manual motor, a 1 HP Brook, driving through a six speed pulley system onto a three pulley headstock.

Chris

[MWParticipant @mw27036]

Anyone notice how the leadscrew drive handle on the lathe is facing towards you rather than being inline with the shaft? Seems to imply some kind of bevel gear arrangement to make contact with it. Anyone know how this works?

Michael W

[CHRISTOPHER MILLS 1Participant @christophermills1]

Michael,

Do you mean Cromwell's Mk II screw-cutting lathe, or the S.800? If the former, I have mine in pieces, and could show you exactly how it works. It engages and disengages a single dog clutch towards headstock. No messing about with dial indicators.

Chris

[MWParticipant @mw27036]

Ah, the S800, It has an apron but no half nuts nor, any sign of a longitudinal feed handle, so i'm presuming the drive handle at the end of the bed is the said leadscrew drive to move the saddle? The unusual fact is that it's facing you rather than the handle being traditionally inline with the shaft itself. So i speculated on whether this was some kind of bevel gear arrangement at play.

Michael W

[Michael GilliganParticipant @michaelgilligan61133]

Michael.

It's explained on the 'Cromwell home page' …

http://www.lathes.co.uk/cromwell/index.html

MichaelG.

.

[quote]

Despite the simplification of the screwcutting and feeds arrangements Cromwell just could not help adding an interesting and well-engineered complication: because the coarse-pitch leadscrew was in permanent engagement with the carriage – and would have been difficult to turn with the usual handle at the tailstock end – two handles were provided,, one at each end of the leadscrew with each working through easily-turned worm-and-wheel gearing.

[/quote]

 

Edited By Michael Gilligan on 06/11/2016 07:33:26

[MWParticipant @mw27036]

Thank you MichaelG. If i was going to get a 2nd hand machine rather than brand new, this would be top of my wishlist, lovely machine. Provides practically every feature a budding small scale machinist could wish for.

Michael W

Edited By Michael Walters on 06/11/2016 11:38:17

[Michael GilliganParticipant @michaelgilligan61133]

Michael,

I've no idea what they sell for second-hand but: The new price was nearly ten times that of a Myford ML7, and not far short of what my parents paid for their first house.

Yes, I'd love one !!

MichaelG.

[WestburyParticipant @westbury]

Hi all,

Chris Mills asked me in an earlier mail how my rebuild was progressing. After quite some time, effort and money, the S800 is usable again, probably for the first time in years! I bought the lathe as a project, and to use as a spare and to give me a chance to recondition my Smart and Brown Sabel.

I stripped the S800 completely to check for wear and to enable a better paint job. What immediately strikes you is the attention to detail on this lathe, from the headstock arrangement to the tumbler reverse gears in their gunmetal oil bath! The gearbox runs in its own oil bath as do all the gears in the saddle. I had to make a metal bench for it, and a 3 phase motor is underslung and driven using a VFD running from a single phase supply.

I have some pics I can post, can someone let me know how to do this, there's no obvious 'paper clip' attachment to include them in this post – or is there?

Thanks for your interest.

Paul

[WestburyParticipant @westbury]

Hi again, pics figured out – I think. This is my S800.

regards

Paul

Hi again, I think I figured out the pics, so attach a couple now.

Regards

Paul

[CHRISTOPHER MILLS 1Participant @christophermills1]

Westbury,

When you go to post a reply, click on the camera image in the posting window, top bar second from right, and then I think you choose your image from your album and click 'upload' or similar – then click in the posting window

It is easy, once you accidentally choose the right method, honest!

I can see an image of your S800 in your album, blue, and a lovely job you appear to have made of it

I have five lathes, four British and a German Karger, and my Cromwell Smallpeice is the only British one which approaches Karger quality

It is why Cromwells are rare today, they were rare in their own day for they were so expensive to purchase

Best

Chris

[Brian WoodParticipant @brianwood45127]

Hello Westbury,

That is a nice job you have made of the Cromwell; I am envious of both that and the Sabel you are going to work on next.

​I was beaten hollow in an eBay auction today for a nice looking Sable, it went for £1120 after 30 bids and I am sure that was not the limit buyer set himself, he swept in out of the blue with seconds to spare to secure the sale.

They too are nice little lathes and quite the best clones of the Southbend that were made.

Regards Brian

[MWParticipant @mw27036]

Posted by Westbury on 19/11/2016 16:45:00:

Hi again, pics figured out – I think. This is my S800.

regards

Paul

I'm envious, just a face meltingly good machine really, i'd be happy to trade!

Michael W

[WestburyParticipant @westbury]

Hi Brian and all

I agree with the comments on the Sabel, mine has been in the family for more than 40 years. I added a T slotted cross slide to it which also gives a useful place for mounting DTI's. The biggest advantage I find is the 3/4" diameter though the spindle. I haven't found many disadvantages! As I mentioned earlier I wanted to give this lathe some TLC which is why I bought the Cromwell. Being without a lathe is not an option! Just recently I acquired another Sabel on its original stand and in quite good condition ( no I was not the other bidder!). It just makes sense to have 2 identical models so as to share tooling etc.

I have to stop accumulating machine tools! Way too many projects!

Regards

Paul

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