Member postings for CHRISTOPHER MILLS 1

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

Sorry, chaps - I have been in error - reading relevant gearbox information plate on the machine, I see top speed for a 13" geared head CovMac is actually 450 rpm, not 335.

Chris

Phil,

I have just noticed, or recalled, that the top speed of our CovMac 13" lathes is just a chugging 335 rpm?

What are the limitations of such a modest top speed?

It compares badly to my Lang Junior, a similar sized machine, which will go nearly 1000 rpm.

What work can we do with these go-slow CovMacs, when we have them running?

Chris

Mike,

Many thanks, I have sent you a personal message. I look forward to hearing from you, about Lang change wheels.

Chris.

Frank, Many thanks. There is no obvious lever to set between lead screw and feeds power shaft. The only control lever addressing these is a right/left reverse feeds/threads lever on the headstock, beneath the main spindle speed levers. This has left and right, and, I am guessing, a neutral in between, whereby the gearbox is disconnected from the headstock. Here is a picture showing it set to 'right'.

Apart from this, there is nothing on the gearbox itself, aside of two main positional levers which set the six speeds. Only Lang guidance in the Owner's Manual says that when not using the lathe for threading, that the change wheels on the external part of the gear box must be left disengaged. This suggests to me that the lead screw is normally unengaged, and that it only comes into operation when it has change wheels attached. That might suggest the spindle is primarily connected not to lead screw but power feed shaft.

Here is another shot, which shows all control levers together - two main spindle speed levers on headstock, little feeds/threads lever between them, two main speed selectors on gearbox, and main clutch control lever. With prime information on the gearbox information plaque being only feed and cut speeds, my initial conclusion is that the lead screw does not work at all without external change wheels mounted, and that power from the spindle goes primarily through the power feeds shaft. I will know more next time I see the lathe in a couple of weeks from now, when I will take off a few covers, and see better what troubles us.

Here is a better picture of my Lang Junior. Despite tired cosmetics, the lathe is in excellent shape, and shows no sign of real industrial use.

This was, after all, John Lang & Sons' hobbyist offering, weighing in at only 1.4 tons. It is the smallest lathe Lang made.

Everything on it is seriously chunky - the drip tray weighs over 200lbs, and, covered in oil, it took three men to manhandle it. The tailstock weighs about 100lbs.

It has an extra foot of bed on standard, @ 7 ft, and came with three chuck/faceplates, and a whole estate carload of cutting and drilling goodies, and tailstock chucks, centres, etc.

Bazyle, many thanks, and I will try your diagnostics when I am next with the lathe in a few weeks.

Phil & Brian - I think we are inching forward on the gearbox status quo.

I have taken possession of a new 'old' lathe, a very hefty Lang Junior 6.5" from the 1950s, and have a query as to gearbox change wheels. The lathe has twin systems, a fixed set of wheels from headstock down into the gearbox, which I have not revealed yet, behind covers visible in this picture, and I do not know quite what they connect to in the screw cutting gearbox.

Then, there is further provision for externally mounted change wheels, to the exterior of the screw cutting gearbox, a banjo and three mounts for wheels.

I have no change wheels with the lathe, and from dry, dusty state of the architecture here, I am uncertain this lathe ever had them. Neither does it have a thread dial indicator.

Only guidance from a Lang Junior Owner's Manual states that change wheels were used for Whitworth and Metric threads, and that when the lathe was not being used for screw cutting that these were to remain unengaged.

This has suggested to me that the inner wheel train connects down not to the lead screw but to the power shaft, but it is by no means certain until I do a bit more dismantling.

Have any members any knowledge of this lathe, or such a system, which seems to me a bit of an oddity.

It is not easy to understand this, without further steps.

The gearbox information plate has no screw cutting guidance, only cutting speeds, surfacing and sliding.

It has six speeds, set by twin levers, and runs in a full oil bath.

Any help will be much appreciated.

Many thanks.

Chris Mills.

Edited By CHRISTOPHER MILLS 1 on 10/02/2016 10:51:52

Here is a better view of my Holbrook CB8, showing all its controls, some of which I have no idea of function in. One lever, central to the apron, has taken a bad bash, and is bent to the left. One refinement is a micrometer wheel which fine tunes movements in the carriage. You can see it bottom right of the apron front, a small wheel, beneath the lock nuts lever.

Thanks gents - I am beginning to ponder electrics in re-converting to variable speed drive.

Manufacture date - Holbrook enthusiasts have identified from their records, and the machine's serial number, 8401, the year this lathe was made - 1950/51.

I was thinking the finish might have been a bit too good for wartime production.

This Holbrook lathe originally ran a 2 HP variable, step-less speed motor made by Ward-Leonard, with a top speed of 5,000 rpm. The strength of machine castings, shown here in an underside view of the headstock, proves how it was designed to take such input.

Apparently, at top speed of 5,000 rpm, according to lathes.co.uk, you could balance a coin, end on, upon the headstock. Probably best an old threepenny bit.

The variable motor is long lost - two previous owners were running it as a single speed machine - it presently has twin pulleys coming off a single phase 1 HP Brook Compton motor.

Thanks, gents.

Manny, I agree - it appears to be a C8.

It is also badged on the headstock plate " D.664 " Nobody seems to use that designation, today.

Apparently, Holbrook enthusiasts term this one today as the " CB8 "

I will be converting it back to a form of variable drive, and any suggestions would be welcomed.

There are choices, from a 3 phase motor with an inverter, or, apparently expensive, a DC servo set-up?

I have been told not to skimp on HP, for reasons of torque

Yes, they are a date, John. I agree, 100%.

Mine and Phil's 13" models were both reconditioned in 1955, by Berridge in Leicester.

Mine was a War Office owned machine in World War Two.

It would seem yours escaped that reconditioning - it was on reconditioning, I think, that mine got all metric changeover information - two brass panels, on the back-gears' guard, giving all wheels needed, a huge number - 26 in all, I think.

Where are you in Kent? I would much like to see your CovMac.

This lift looks alarming, but this was the only way to balance and pick up a Holbrook Model B No. 8. Heavier than I thought, it was a struggle for three of us to get it in the Passat - we got it out with two, under less hurried conditions. I reckon it is between 500 & 600 lbs of metal.

It is now safely stowed, and we damaged nothing, and nobody got hurt. The engine crane, as with the CovMac - a delightful lifter - but, with its steel wheels, a really terrible mover on anything but marble smooth surfaces. I might convert this baby to take rubber, mini car-type wheels. Any suggestions would be welcome. With rubber wheels, I am sure this would be so much more versatile a machine to use.

Edited By CHRISTOPHER MILLS 1 on 09/04/2015 09:33:19

John,

Fascinating - on which part of the lathe have you found this very crucial date?

It would be nice to think mine and Phil's may similarly be dated - I have not gone over mine fully yet, with a fine tooth comb, but I have found nothing remotely like a date.

Many thanks gentlemen - Sorry, Cornish Jack, it is of 4 inch centre height.

Lathes.co.uk certainly like this model, thanks Ady1 - "Famous for their high quality toolroom lathes, the English Holbrook Company concentrated mainly on popular and hence profitable medium and larger-sized back-geared and screw-cutting models - although they also made a superb, almost-Rivett-like precision bench lathe, the Model B No. 8."

It sounds like praise indeed. I am yet to see any imagery which shows me fully how the cone pulley and motor were organised together, behind the headstock.

It will be a bit clearer when I have the lathe in my possession. Moving it is not the feat of logistics which was needed to move the CovMac - the little Holbrook will go into my car.

Just to remind, pertinent of my careless lapse in publishing a picture of a dangerous set-up, kindly pointed out to me by the alacrity of our Editor -

NEVER LEAVE A CHUCK KEY IN A CHUCK

No excuses, no lapses. No nasty accidents.

NEVER LEAVE A CHUCK KEY IN A CHUCK!

Please.

Edited By CHRISTOPHER MILLS 1 on 04/04/2015 20:23:29

Edited By CHRISTOPHER MILLS 1 on 04/04/2015 20:25:40

Not me, Neil, it was the vendor. But he had at least taken it out before I arrived on the scene.

Oops, though, I am now remembering your publication protocol - and if you want to remove that picture, Neil, I am happy to get a better one without the chuck key.

To add to my 1940s CovMac, a large lathe, I have this week fortuitously acquired a little one, from the same era - a Holbrook Model B No.8 Toolroom lathe.

A little beauty, with taper turning, it is presently lacking its pulley cone gear and counter-shaft. I would ideally like to connect with another owner, (or somebody with knowledge of this model), so that I can work out what it needs to complete these areas. I am just to be guessing at present. There is some remainder of counter-shaft arrangements on the back of the headstock. At present it only has, effectively, a single gear, running off the motor, its top speed of 1320 rpm. For its age, I would say it is in pretty remarkable condition. Very little needs doing to it, apart from cleaning, one or two lever knobs replacing, and pulley cone and counter-shaft replacement.

I will post more detailed shots as I go. This model of lathe seems to be highly regarded by Holbrook enthusiasts, and I am looking forward to ownership. It will help me complete a number of items contingent to restoring the big CovMac.

Holbrook, a firm based in Stratford, east London, later moved out to Harlow, Essex, and they were eventually subsumed, I believe, into the Alfred Herbert Group.

Of about Myford proportions, overall, 4 inch swing, and about 20 inches on the bed, I think she weighs about 500lb. It came with a 4 jaw and a 3 jaw chuck, taper turning unit, and a bit of cutting equipment, a few dead centres, drill chuck, etc.

Am bringing her home on Tuesday this coming week.

I would also like to track down visuals, or examples, of centre and travelling steadies, which I believe came originally supplied with this Holbrook model.

Most striking visual feature of this lathe is a milled front face to the whole bed. I have never seen that before. It is quite striking. It does not show up too well in this photograph. It has 27 screw-cutting options off its nine cog gearbox. How we attain three off each gear is not quite clear to me, yet.

Edited By CHRISTOPHER MILLS 1 on 04/04/2015 14:01:52

John,

Many thanks - where in Kent are you? I have family in Canterbury & Folkestone, and I appear periodically.

I would love to see this lathe of yours, some time.

I thought your sliding/surfacing boss was an adaptation, and it has set me thinking as to how I renovate mine - mine took a lot of abuse on the knurling, and now I think it might best be re-knurled with extra grip in mind.

How long have you had her?

Hello John,

Many thanks for the posting. Yes - we know of just the 6 surviving CovMacs, three 13" and three 17".

Mine is partially through being renovated - simplicity of the engineering is impressive. The screw-cutting gear-box needed comprehensive work - it is in the capable hands of Brian Wood.

Have you ever had any of yours apart?

Can I please see a close up of the sliding/surfacing control boss - it looks very different to mine. 

Do you think your paint finish is the original?

Edited By CHRISTOPHER MILLS 1 on 31/03/2015 14:37:32

Edited By CHRISTOPHER MILLS 1 on 31/03/2015 14:38:20