Monarch 14c Spindle Speeds

Hello all,

I own a Monarch 14c lathe which is 14X54. Vintage is 1944. It is rated as a slow speed lathe as from the factory max RPM is set for 800 (or something like that). I was wondering if I could change out the drive pulleys and run it up to 1,200 RPM? Would that be risky? I popped the gearbox cover and that gearbox is amazingly constructed. Blew me away. BIG helical gears and equally large Timken bearings. Very impressive, looks like it would do fine as a transmission in a Kenworth Diesel long haul truck.

Right now my biggest concern is the 3 jaw chuck on it might not be rated for 1,200 and could fly apart. That really would ruin my day.

Any opinions on the up-speed change?

Thanks
Randy

I upped the max spindle speed on my ‘44 CK from 550 to 1100 by putting in a new motor and VFD. 1100 rpm is pushing it on mine. Although a complete overhual is in progress, I expect 800 rpm to be a realistic max.

For the motor I went from a 1200 rpm stock to an 1800 rpm motor. Had to fab an adapter as the original motor (254 frame?) was bigger than a current era replacement. That gives a 1.5x speed boost.

Running with the VFD at 80HZ on the 1800 rpm motor puts it at 2x speed on the spindle. I used the VFD as a way of getting 3phase more than for variable speed, so unlikely to use this as 2x (1100 rpm spondle) feels too fast. That could change as I rebuild with new bearings, but I doubt it.

I looked at changing the pulleys but decided that while mechanically simple in theory, the housing clearances and clutch construction didn’t make that theory practical.

All in all, have you run it enough to really decide you need more than 800rpm?

And yes, I replaced my chuck.

Owned a CW16 for over 20 years - never been to the 700 top end yet

If you want to go faster, at least disconnect oil lines to spindle bearings and see if they actually flow oil thru the Bijur metering units adjacent the bearings - you do this by running the lathe - slowly to avoid oil showers - with the cover off

Then buy yourself some good ear plugs so the extra NOISE from the left end gear train will be less objectional