"Richard W." wrote ...
"john" wrote...

If you bolt the lathe to the concrete floor you can make it a lot moe
rigid. Also proper leveling makes a big difference. There is an art to
doing long thin parts without getting chatter, a steady rest or follower
rest being manditory.


True, but a lathe with wide ways helps a lot. Tarnows have narrow ways. At
least the ones I have used.


Checking the spec' (translated as best I can from the original Polish, will
go see my Polish friend Mata if I get the manufacturer's handbook!), it
looks like the width of the ways on the smaller ones like this is about
equal to twice the centre height, and not having a bed gap might help
rigidity some? A new reinforced concrete floor (6" or 8" slab with top and
bottom steel mesh on insulation slab over compacted rubble and sand
blinding) is on the cards whatever I end up buying, and ragbolts into the
concrete would be wise, IMHO, to minimise vibration. I've seen machinery
dance across the floor when it hit resonant frequency, don't fancy 2 tons of
lathe chasing me out the door... 1/4 ton of rock'n'rolling ICL chain-printer
was bad enough.


I would not recommend using an underrated VFD. I would spring for a
single phase motor of about 5 hp or so and eliminate all your other
electrical problems. It would probably be cheaper in the long run and
would also make the lathe easier to sell.

I would run a rotary phase. My P&W has a 7.5 HP motor and it works just
fine.

I was thinking of a VFD as a measure of future-proofing as at some point I'd
like to add a smallish mill to the toolkit, and rotary convertors take a
fair amount of real-estate - not something I'm particularly blessed with
(SWMBO would rather have other luxuries and space for our motorcycles in the
Big Shed!) - and it looks like there's not a lot of difference on price. A
single-phase motor in that power bracket is probably going to cost more than
the VFD, too, and would still leave me with around half the original
horsepower and needing a rewire for the "shop" power...

I've seen a few smaller lathes run on "undersized" VFDs without too much of
a problem, and to be honest the lathe has speeds from 17 to 2800 RPM and
plenty in between straight off the motor, with drive clutches so the motor
would be able to spin up without the added mass / moment of the spindle and
workpiece? I appreciate that it might limit the amount of chips I could make
per minute, but this is for serious hobby use, not a production shop, and my
concern is more that runing the motor on an undersized VFD could cause
issues for the motor - not being an expert on induction motors (more optics,
RF and microwaves, really) I'm open to the collective wisdom of the group!

Thanks again,
Dave H.
--
(The engineer formerly known as Homeless)

"Rules are for the obedience of fools, and the guidance of wise men" -
Douglas Bader