Satisfaction.....

Aaah but Monarch made the EE 1000 which was available in 30" and 54" BC so not only can you throw the half shafts in, you can also throw the driveshafts too.

Tom

Reply to
Tom
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That CVA has been on before, didn't sell. I think I'd want to see it before deciding it was worth the start price, the photos aren't exactly flattering. I bet it hasn't been turning candles since new, who knows what it might have done in a past life ;-)

The CVA is no wimp, later ones have a 4hp motor which is more than my Colchester Student, with bigger capacity, had.

Tim

Reply to
Tim Leech

The high start price frightens people off. However, The state of the paintwork suggests that it has been treated with at least some respect for at part of it's life, despite it's scruffy exterior. Perhaps an odd metric, but a machine with half the paintwork chipped off is not a good sign imho. Worn away, patina (ugh) perhaps, but abuse, no.

I would *never* suggest that it is wimpish, but a typical target market for such machines would have been aerospace - difficult to machine / exotic materials which need the torque, but combined with very tight tolerances and good surface finish. The more you use such a machine for general hack work, the sooner it's accuracy degrades and which one of us could afford to rebuild or have it rebuilt to its original spec ?.

I guess what i'm saying is that a well worn cva is no better than a Colchester in terms of it's finer qualities and far less in terms of spares cost and availability...

Chris

Reply to
ChrisQuayle

I'll give you the availabilty of people breaking Colchesters as a benefit. However if you come to replace the headstock bearings then the Gamet ones (600 Group proprietry bearings) are a real wallet buster. Other machines have standard sized units which are much cheaper.

Charles

Reply to
Charles Ping

On 16 Jul, 14:55, ChrisQuayle wrote:.

Chris, this is not my argument and I'm neither a CVA or Colchester man particularly but I would not totally agree with your last statement. In my working life in Aerospace I was responsible for a large manufacturing area and we bought many machines each year. Believe me, if we could have got the same performance from a new Colchester as a worn CVA we would have done so. Even 15-20 years ago finding someone who could rebuild these types of machine properly was really difficult and not a little expensive. I know in our world we did not work these machines like some production tool rooms but we were demanding of their accuracy and finish. Although most of our money was spent on CNCs even in the manual machine world we would buy a handful of new machines each year, the Colchesters and Harrisons were fine in the maintenance and training areas but the production/toolroom lads weren't keen. I remember taking out a top spec Colchester which had been put into the precision turning area to try and wean them off their old DSG/CVA/Holbrook/Mikron machines, after five years it had run less than 450 hours!! The truth is that the guys would rather use a 25 year old "precision machine" that had run for thousands of hours than a brand new "clunker", sorry but that was their term for the Colchester.

Now for my own garage I certainly wouldn't kick the Colchester out unless it was for a virtually unused Holbrook but that is just personal choice and reflects my capability as much as the machines. I partly agree with your comment about general hack work and the truth is that these machines have been extremely cheap for a few years now (rebuild/spares costs) and have usually been through a hard working shop on their trip from Aerospace to E-bay, so a great deal of care has to be taken in buying the right machine but they are still about. Obviously, if you have the time and skill a personal re-build is a much cheaper option to recover them to reasonable condition.

My involvement was in a number of Aerospace machine shop areas and I must also say that like in many things, "personal taste" has a huge part to play in what machines are "flavour of the works". With a number of shops located between Scotland and the south coast we saved money one year by moving "useless scrap iron" from one site where it was not appreciated to another shop where it was "manna from heaven", there is no accounting for taste!! The one thing I did learn though was that people were happier and much more productive if they had a machine that they liked rather than one the accountants liked.

All this has taught me that when someone says "what lathe should I buy" my reply is usually "well what machine do you want"? If someone is looking for the feel of CVA/DSG etc but hasn't got the room then a good Myford is likely to go down better than an import, good as they are getting these days. It's all in the feel.

Regards

Keith

Reply to
jontom_1uk

I replaced the spindle bearings in my CVA , with the proper spec, for around 200 quid. I doubt you could do that in a Colchester.

Tim

Reply to
Tim Leech

Perhaps comparing that pair is unfair, but even a cva will wear to the point where the accuracy makes it camparable to a fair condition Colchester. I'm sure the guys in your company had mechanical sympathy in terms of running the machines well within their limits and there was probably enough choice to always choose the right tool for the job so you never had to do inappropriate work on any of them. You probably had a regular maintenance program as well, something smaller companies can't afford. If it's anything like electronic design or software engineering, even stuff like checking oil levels becomes part of the process and under such conditions, machine life can be measured in decades. As for preferences, I guess once you get used to using the best, anything less becomes a set of irritating compromises. Every machine has its quirks and it takes time to get the best out it. Even worn examples produce good work in skilled and familiar hands.

It's decades since I did any serious machine shop work, but remember the Myfords as being great for lightweight stuff, especially with collets. The Colchesters were good, robust and honest machines, but the thing I still remember most of all about them is the mechanical noise from the gearbox and lack of subtlety in general. Someone told me that they were the first mass produced lath in the uk, built to a spec and price to suit a particular market. Nothing wrong with that and perhaps it was pretty worn when I got to it, but the Myford was much smoother and tactile, if you ignored the imbalance and vibration at higher speeds. I wonder if they dynamically balanced the headstock and countershaft assemblies, perhaps not very well.

To get me back into it all, (and back down to earth :-) have initially bought a Boxford A, but am already thinking of ways that it could be improved. For example, throw away the countershaft and spindle pulleys and substitute taperlock poly V or flat belt drive straight to a 2Kw

2850 rpm motor. Drive from an inverter with added logic and control panel for stuff like inching and program the inverter for torque limiting etc. There's enough space to bore and fit taper roller thrust bearings to the cross and top slide thrust faces and there many other areas that could be improved. That and a bit of hand scraping to finally set the thing up. The bed doesn't look that rigid, but there's a flat area in the bed centre that could be used for a third mounting point to improve rigidity. Mine was a bench mount model and arrived on a 1" piece of wood and cast iron legs, but have already welded up a new frame from 5"x2" angle, which should stiffen everything up quite well. Of course, this won't turn it into a Cva, but should be capable of quite accurate work, used within it's limitations. Perhaps an S&B or Holbrook will turn up later. I do want to stick with a Brit machine though if it can be found at a sane price. Perhaps a Brit machine to take me back to my own machine shop years, who knows, but it will be a real asset to the business as well.

Agreed - The initial capital cost of the machine is negligable compared to the, cost of labour and power over the machine life, so everyone wins. Enlightened management is a rare resource however. Problem is that companies are now usually run by beancounters who only see short term bottom line and seem incapable of grasping the long term big picture. Business school only taught them how to add up and the shareholders are greedy etc.

A few more reminiscences would be appreciated. Have worked for more than one aerospace co, but in electronics and software. Never saw anything of the mech eng side other than through other interests in historic aviation...

Chris

Reply to
ChrisQuayle

Agreed, one of the things that defines the accuracy and possible finish etc of a machine must be the headstock bearings, which is perhaps why some manufacturers stuck with plain bearings for so long. The problem is not that each individual component, say spindle and bearings have runout and other irregularities, but that the cumulative error may be additive or subtractive once the whole thing is assembled. For the very best machines, one would guess that they selectively fitted spindles and bearings against all sorts of parameters to conform to the final spec, but there seems to be no information on the production process, which would make a very interesting read. It's not so bad if the spec is

0.0005" runout total, but the parts start to get expensive if the spec is a 1/10th of this or better, especially considering the age in which such machines were built.

About the 4hp motor - from what I can see, the reason they needed this was to make up for the power loss in the mechanical variable speed drive. To be honest, there are quite a few things that I don't like about the CVA, quite apart from its shear bulk, which was probably helpfull in masking out of balance components (cynic). The variable speed drive might have been state of the art in 1960, but is positively antiquated now. It could be replaced with more modern motor and space vector inverter, which would remove rotating parts, maintain torque down to low speeds and improve efficiency. If we are talking about perfectionism, i'm not sure about the apron controls either. (The Holbrook looks a model of clarity in comparison) Also, the main spindle looks like preloaded ball bearings, which don't look adjustable and probably cost a mortgage to replace, not to mention the lack of info and skills required to set them up.

This discussion is interesting and it would be good to find out what the original specs were for lathes like cva, smart & brown etc in terms of accuracy, spindle runout etc. There seems to be little on the web in this respect. In essence, what defines a "precision lathe" ?. What were the key techniques used to get the improvement over the average machine ?.

Chris

Reply to
ChrisQuayle

I'm not aware that any CVAs were built with a 'mechanical variable speed drive' A small number right at the end were built with a variable speed DC motor drive, but the vast majority had a 12-speed gearbox. Are we really talking about the same machine?

Cheers Tim

Reply to
Tim Leech

I own, dare I say it, a Monarch Toolmaker's lathe, everything including the apron has shafts rotating on taper roller bearings, however when it comes to thrusts, the top slide, cross-slide and tailstock are catered for by 3 piece ball thrust bearings. I really think your idea of fitting them to a Boxford is a bit OTT.

BOT Monarch were the first to fit taper roller bearings in machine tool spindles.

Reply to
Tom

Oops - brain fade - It was the Holbrook used mech drive and as you say, the late cva that had electronic speed control. Looks like a lot of it though, judging by the size of the control cabinet, though not clear if this was ward leonard motor generator or thyristor control. Even as an electronics bod, would be concerned about buying into such an early drive system. It was early days for such technology and all the components would be pretty well aged and reaching end of life by now. A

3 ph motor and inverter would cure all that however and would still be a valid update for the earlier gearbox models as well.

Assuming the headstock, bed, saddle etc are all in good condition, there must quite a few early lathes that could be updated to a better than new spec using more modern components and technology. From what I can see, many of the early high end machines were substantially overengineered, even if some of the driveline technology was a bit iffy...

Chris

Reply to
ChrisQuayle

Why ?. The original thrusts on the Boxford are copper washers, but they are worn out, so why not fit something better ?. It's not a great effort or expense after all - about an evening's work. The Boxford may have been made to a price, but all the basic metal is there per it's more expensive brethren, so why not turn it into something better ?.

Perhaps they were, but so what ?. One could still argue that plain bearings are better for the headstock spindle, but taper rollers are cheaper in manufacture and easier for maintenance. I do prefer the look of the 10EE to the cva though, whose slab sides contain more than just a hint of 30's Italian architectural brutalism in the look of them. Just so arrogant. Perhaps that's what irritates about them - can't think of any other good reason. There's no doubt that they are good machines, but they were obviously trying hard to prove it as well.

I prefer my machines to have curves and gentle slopes - it's much easier on the eye. As Keith said in previous post, it's all in the feel and personal preference, especially if you have to work on a machine every day...

Chris

Reply to
ChrisQuayle

including the

Reply to
Andrew Mawson

What a lot of twaddle

Have you actually *seen* a CVA? Or a Monarch 10EE? Or used one? You're no doubt aware that there were two main, very different, styles of CVA, just as there were two main styles of 10EE.

FYI the 10EE, like the CVA, uses angular contact bearings on the spindle, not taper rollers.

I had a Boxford for a while, I don't remember too many graceful curves & gentle slopes My DSG has those, it means there's nowhere to put anything down......

Tim

Reply to
Tim Leech

I think they are copper, at least the right color and flexibility. I don't know how thick they were to start with, but only about .003" thick now, if that. This is at the micrometer dial end and were probably originally near full dial diameter...

Chris

Reply to
ChrisQuayle

It's all about preferences, to me the curved shapes of the round head Colchester's smacks of 1950's and runs into the modern day German designs. Did you know that under the second treaty of Versailles, because they ignored the first one and carried on making tanks and planes, they took all the rulers off the Germans so they couldn't draw a straight line.

Don't believe me ? Look under the bonnet of a Merc or Beemer, not a straight line in sight, even the heater hoses go in a big curve from the front off side to the rear bumper and back up the other side via a No 47 bus stop.

You say they are easier on the eye but so what. I buy a lathe to use not look at. Slab sided means it easier on the patternmaker and so easier on the wallet.

Last brand new lathe I bought and I mean lathe, not counting the odd Chinese hobby thing to play with, was an East European TOS, slab sided, one coat of paint onto bare castings, hardly what you would call pretty but you could air drop this on Bosnia and it would still turn to 2 tenths.

Anyway most important point is "Where can you keep your cup on a roundhead Colchester or 10EE ? "

Ipso Facto, - case rests.

Reply to
John Stevenson

I was just making the point that Monarch along with most most lathe manufacturers were, are content to use 3 piece ball thrust bearings.

If you think you can fit 2 taper roller bearings to your cross-slide screw obviously Boxford left you plenty of room. However I take you're a stranger to a bearing specification manual? >>

One could, but one would first have to get the sand out of one's mouth. >

Whatever John said... >

Never turn down a chance to try a CMT Ursus then. They make any DSG feel like driving a Model T. >

BTW BOT = Bit of trivia.

Reply to
Tom

I rather like that response.

Probably sums up what most of are thinking.

Peter

Reply to
Peter Neill

To be honest, haven't got to that stage yet, just random thoughts and seemed a good idea to improve the feel of the controls by putting some better bearings on the spindles. Thrust ball races are probably the most economic solution, but there is room for taper rollers at one side at least and may even have a couple of small examples already on the shelf. You know, stuff collected along the way at some time or other.

Don't know about sand, but admit, rapid switching between cross-slide and spindle bearing discussion probably doesn't help comprehension :-)

I still like the idea of plain bearing spindles, however impractical. Having said that, many of these machines are 40+ years old and you might find that bearing production tolerances have improved to the point that exotic class bearings of the period are now a mass produced off the shelf item, with the really good stuff now an order of magnitude better or more. Would expect to have to do quite a bit of work on an old machine and gut feeling suggests that they be turned into something even better than original using more up to date techniques. You know - keep the best of the old, but move with the times as well.

in a sort of related way, a friend who runs cnc machines was telling me that some of the cnc control software provides facilities for compensation of machine wear or non-linearity. A lookup or calibration table for the machine providing continuous correction during machining. Have used similar techniques to linearise and temperature compensate pressure sensors, but had never thought about it at all in terms of machine tool control. In the old days, they made em big and strong to get the long term accuracy. Now, if true, it appears that software compensates while a much lower spec machine wears away. Obviously a lot of catching up to do here.

I won't - pursuit of excellence is always rewarding, even if a little unfashionable these days...

Chris

Reply to
ChrisQuayle

There aren't, but you have to start somewhere.

Agreed, but you could always fabricate a cupholder :-)...

Chris

Reply to
ChrisQuayle

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