CVA lathe

[Beckerkumm]

Finally got possession of a CVA lathe which are pretty rare here in the US. The spindle, headstock, apron, and gearbox are pretty much a direct copy of the early 10ee Round Dial machine with the later 12.5" swing. This is a very rare version with the clutch drive into the twelve speed gearbox rather than the much more common electrical forward and reverse levers.

The clutch has serious slippage issues making assessment difficult but while there is some wear on the ways, it is less than on my Smart Brown 1024 and seems to be less than .001 until you out to tailstock territory. The gears and insides look very good and knobs and levers show less wear than what I usually see. I might go the extra way to have the ways ground to return this to Monarch standards. Monarch licensed their design to Kearney and Trecker in England who with Cole made them until the 1970's. This looks to be a 1951 version that was updated ( in a homely sort of way ) from the original which looked very much like the 10ee. The speed range is 49-2220 with twelve speeds and a range of very fine feeds running from a flat belt in addition to the normal gear driven and screw feeds. This project will take some time and some help but hopefully will be fun project. Finding parts from the UK and Monarch is actually a little easier than for the 1024 but still not for the faint hearted.

More to come. Dave

 

[Beckerkumm]

A few more pictures. This is the vector motor I may use as a replacement. Due to the linear nature of the speed ranges, going to a vfd and regular inverter duty motor ( saving this motor for another use ) might be the route I go. To get completer coverage from 0-3300 rpm would only require a motor to run from 40-90 hz so this Black Max might be overkill. I'll talk to Mark here about that.

This is the clutch that will need work. Dave

 

[Aukai]

Good looking machine.

 

[Martin W]

Congratulations. Very nice!
Cheers
Martin

 

[Beckerkumm]

I've working to operate the CVA enough to judge wear. I did the Smart Brown ass backwards and rehabbed all the mechanicals before really assessing how it turns and wanted to be less dumb this time. The clutch still slips horribly so surface finish is crappy but I took apart the compound, cleaned it up and surface ground the top along with a new T nut for either the Dickson or Multifix E. There is about .015 backlash in the screw. The cross slide was also cleaned up and I removed a layer of the laminated shims between the top and bottom halves of the nut and reinstalled. It is actually a little too tight now so it will come off again before I die.

Due to the clutch I took light cuts and locked the cross slide which is cheating a little but a 1" bar extending 5" resulted in about .0001 over the length. My ability to measure .0001 reliably is suspect but I'm still pretty happy with the 70 year old machine. I'm about the same age and my performance has suffered way more. I'm sure as I get out on the 30" bed there will be more variation but my S and B would show more like .001 over the same 5" and I can work the tailstock to get that or better over 12" so this machine should be pretty adequate.

I'm not looking forward to pulling the clutch as I'm sure it weighs about the same as a 747 but there is no cure for dumb so I'll give it a go. Clutch is attached to the gearbox box on the left so the whole unit needs to come out. Dave

 

[Beckerkumm]

Took out the motor, gearbox, and clutch today. Unlike my Smart Brown where everything I went into had been previously mucked up, I don't believe the gearbox had ever been opened. Very little crud and when the oil drained it looked pretty good. What is unusual is that spindle speed changes are made by turning a round dial that has a spring loaded ball that engages a detant. you can see the curved line the adjuster follows so the ball and detant match the high and lows of the curves tather than snapping into place. To my eye the gears look to not have been mashed too much over the 70 year life.

 

[mksj]

Looks in surprisingly good shape for its age, oil looks clean with no water/debris. Might be able to go with a smaller motor pulley for the Black Max motor, either way you should be fine using it in a 20-90 Hz range with the stock pulley/gearbox, being mindful of the upper spindle speed. Seems like the link belt is because the gearbox pulley is captive, seems to be a clutch or linkage? I would still look at switching the belt out if possible. You might be able to put a VFD in the tailstock cabinet or mount a cabinet off of that end. Do you have the tailstock?

 

[Beckerkumm]

Tailstock but no steadies, yet. Have one sourced in UK with some other parts. New belts are coming and yes they must go on before the clutch. The clutch was difficult to remove but mainly because I didn't realize a pin had a slight taper .515-.495. Now that I know that I marked the parts so I can tap out. I'm hoping the clutch plates don't need reworking. They look good but the friction plates are kind of glazed.

What you see is just the residue after I rinsed the box with kerosene, but the oil looked good on the way out. It will get new DTE Medium. Headstock recommends medium for the headstock but since I intend to speed it up a little I will go the DTE Light which is what monarch ran in the same design.

The spindle pulley has about a .025 wobble so that will get replaced. I could rebore for out of round but don't know how to fix sideways variation. Later machines used a flat belt for the spindle and I have a pulley for that but not the mating drive pulley. Dave

 

[FOMOGO]

Nice machine. Looks a lot like a motorcycle clutch. Mike

 

[Beckerkumm]

I'm looking for replacement plates in the third picture if you have ideas. Thanks, Dave