Depth of cut cowells me90

[kinross1Participant @kinross1]

Hi Jason.
Just had a look and I do not think that the nut head is meant for adjustment. I could undo it a little but as I am now able to cut . 5 mm without a problem I will settle for that. My belts do seem very tight. As has been posted the secret is to keep them and pulleys clean of oil etc.

Thanks. Mike.

[old martParticipant @oldmart]

Half a millimeter is close to 0.020″ which is an admirable result for your lathe, I would rarely cut that deep on a much bigger lathe with carbide inserts of any shape or grade.

Remember to oil your bearings every time you use the lathe when the belts are tight.

[Roger WoollettParticipant @rogerwoollett53105]

The Cowells ME90 should deal easily with 18mm silver steel.

If you are getting belt slip I suggest you should use the backgear. In any case I would start with 240rpm.

I use HSS tools and in this case would want around 10 degrees top rake (opinions vary). Make sure the cutting edge is really sharp.

If the cut is any length I would use the auto-traverse and probably a touch of neat cutting oil.

I have not tried this out but I would expect a 0.5mm cut to be reasonable. Perhaps less to finish.

[kinross1]

On kinross1 Said:

Hi Jason.
Just had a look and I do not think that the nut head is meant for adjustment. I could undo it a little but as I am now able to cut . 5 mm without a problem I will settle for that. My belts do seem very tight. As has been posted the secret is to keep them and pulleys clean of oil etc.

Thanks. Mike.

Jason is quite correct: the Cowells ‘manual’ confirms this, and refers to a locknut on the screw, although I think this may not always have been fitted. The headstock drive belt does need to be ‘twanging’ tight.

I do not know what new belts are like, but those on my second-hand ME90 have developed(?) a glossy, slippery, hard-ish surface. The headstock spindle bearings piddle oil everywhere they can, including onto the spindle pulley, resulting in belt slip. I’m afraid that’s just another example of the primitive design of this lathe. It’s essentially a 1920s-style design, with none of the improvements that a century of small lathe development has brought, and includes major design features that are now considered just plain wrong. I’m very disappointed by my machine, and am highly amused by today’s prices. Fortunately, mine was almost like new and not expensive.

I note that Cowells have (at last) revised their web site, and show a new address. Does anyone know what has happened?

[bernard towersParticipant @bernardtowers37738]

perhaps they moved to avoid the complaints

[duncan webster 1Participant @duncanwebster1]

I fitted mine with 3 phase motor, vfd and tooth belt drive between countershaft and mandrel. Did away with back gear as I have a bigger lathe for jobs needing slow speed. That cured the belt slip issues.

I still sold it eventually, needed the space.

[JasonBModerator @jasonb]

The older owner retired and a new one has taken over.

 

Thanks for confirming my thoughts on the adjuster. Below is a photo from a Cowells promotional flyer when the ME version was launched which shows what I correctly thought is an adjuster.  Th ehead of the screw rides on teh cam and if it were not there then the tension lever would not work as the cam has nothing to bear against.

I had heard that the “Modern” addition of a plastic cover on the ME also helped coat the gears in oil as it hit that and dripped back onto the running gear.

[JasonB]

On JasonB Said:

I had heard that the “Modern” addition of a plastic cover on the ME also helped coat the gears in oil as it hit that and dripped back onto the running gear.

 

Indeed – the cover keeps the drive train well lubricated… It also can’t be closed whilst using the rather nice little Bison 3-jaw chuck that came with my lathe. Not sure whether this was originally supplied with the lathe or not. I think that the cover could easily be moved by drilling new holes for its hinge, but why bother? It’s more convenient to use the lathe uncovered anyway. Sometimes one just has to live dangerously…

Good luck to the new owners; I suspect they’ll need rather a lot of luck. Leicester seemingly couldn’t provide anyone to take over ARC, and has lost a number of well-respected engineering equipment manufacturers in the last few decades, all of which is a great pity.

[kinross1Participant @kinross1]

The first thing I did was remove the cover. I also do not use shields on grinders etc. old school I suppose but I do wear safety goggles and even a coat as her indoors gets one on her if I get chips and oil all over my jumpers.
To recap I think my troubles stemmed from oil on belts.
Refining tool shapes etc was just clutching at straws. My tools are sharp etc. I can now cut .5  mm no trouble

In some ways I regret moving my Myford on but there were various reasons for that. I do have a decent mill.
Mike.

[teamrickyParticipant @teamricky]

Hi,

 

Thanks for sharing your findings especially with a specialist lathe 😉

 

I certainly have experienced one way or another most of the issues that kreep in with this scale …. I just wanted to add a tool that I’ve found that I will buy this week !

I spent ages working towards more rigid set up as you had to and adjust/replace any worn parts , Thing is parting and process of steel bites you ! After all the tweaks I think this 1mm indexable’  multi tool’

It’s possible to buy in 12mm and 10mm shank

and buy the inserts below for one shank 😁

I think it will help ppl with the smaller less rigid machines

 

[JasonBModerator @jasonb]

I did try one like that on the Emco, a modified 1mm cutter to get teh height down low enough. Failed on the silver steel, would just about work on 22mm mild steel. OK on smaller stuff.

However as the part the OP wanted to part was 18mm it would not have been long enough anyway as 6mm is the deepest it will go. I have a number of different width insert sfrom 0.5mm to 1mm and also rounded ones.

I use the Mini-Thin

[JasonB]

On JasonB Said:

well as that is what Cowell’s choose to put on their website a san example of the machine in action then they ar enot showing it in a very good light. As I said I would have expected one to perform about the same as my similar size Unimat.

But as you have three of them perhaps you could answer the OP’s question and say what DOC he should expect in 18mm Silver steel?

I would have expected speeds and tool type/position to be beginners issues but a sthe OP has previously had an SL and Myford should know how to sharpen and mount a tool.

I don’t find the brazed tools to be much of a problem and do use them fairly ofyten, that 190mm Cast Iron “bit on the side” thread of mine last week had some of the machining done with a brazed tool. Also that Minnie in my avitar was almost all done with brazed tip tooling.

Anyway I thought as the U3 wasw still out on teh bench I would take a couple of cuts in some 25mm dia cast iron. 0.5mm DOC seemed fine and a faster feed than in the Cowells video with HSS, Inserts and brazed carbide all working well. (first cut is actually 1mm

The videos on the Cowells website are made by a customer.

The DOC OP will get depends on multiple factors as I’m sure you know. I personally don’t chase DOC numbers but I would say around 0.5mm would be satisfactory on any micro lathe.

I sometimes use the analogy that anyone using a 1/4 scale lathe should expect one quarter the performance.

[Hollowpoint]

On Hollowpoint Said:

On JasonB Said:

well as that is what Cowell’s choose to put on their website […]

The videos on the Cowells website are made by a customer. […]

 

Yes, but Cowells still chose to feature them

… probably an error of judgement.

MichaelG.

[Richard BParticipant @richardb44403]

The tension  adjuster bolt threads right through the casting and a lock nut is provided where the threaded end exits. I have not had much need to adjust it when set.

I don’t have numbers for depth of cuts – I just set the machine to work respecting its size and the job in hand – all machines can be worked hard but it will eventually effect their longevity and accuracy.

Sharp tools are essential – HSS, carbide and inserted tips (small radius) all work well.

Assuming the belts are not worn out and wiped clean occasionally I don’t over tighten them. A belt slip with a small component can save tears !

I have had mine for about 40 years and have built Stuart 10s Double 10s and a fair bit of my Minnie on it.

My GRP cover fits fine with the excellent Pratt Burnard chucks supplied with the lathe. I would not use it without as fine iron and hard brass swarf/dust would cause damage very soon.

I don’t part off on it -saw off and face back.

I didn’t know Colin had sold the business – always very pleasant to deal with. I wish them well.

The back gears down to 60 rpm is something not found on many of the modern small machines and useful for large diameters in the gap bed.

I have a 250mm swing Denford for larger work with a Newton Tesla variable speed drive. Mitsubishi inverter ISTR – excellent conversion and has been reliable (famous last words !).

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