Far Eastern Variable Speed Lathes

[Julia]

I am looking at purchasing a new lathe and some of my candidates emanating from the Far East have integral variable speed motors. What sort of motors do these have?

I would like to know whether these lathes have enough torque at low speed. I was shown a lathe with a 18" swing in the gap but it was fitted with a variable speed motor that achieved 100-2000 rpm without changing gear. My gut feeling it that at 100 rpm the torque/speed would be unsuitable for 18" eg turning a large fly wheel.

Has any one got experence of the Warco WM280V-F?

Unfortunately I do not have room/access to get a traditional large lathe into the house. Clearly such a machine with 3 phase motor and phase converter would be the best option.

Julia

[Richmond]

Julia,

I am confused. The lathe you mention doesn't have a gap piece, and has an 11" swing according to the Warco website, not 18".

For the money perhaps you should consider the BH600, very similar footprint, and will swing 17 or 18" in the gap.

Keith

[ettingtonliam]

Julia
I have a Chester Conquest with variable speed drive, and the quick answer is no, these machines don't have sufficient torque at low speed . My machine will swing 150mm over the bed, but it certainly wouldn't be able to handle a cast iron flywheel or loco wheel of that diameter. Its fine for bar work up to about 50mm, but above that it struggles. Fortunately I have a larger 'conventional' lathe so it isn't a problem, but I wouldn't recommend electronic variable speed machines if you want to to use them at anything like their full dimensional capacity.

[Julia]

Keith
The BH600 was top of my list until visited Warco at Fisher lane. The 18" swing was on the newly introduced GH1224VS. My issue with the BH600 is that it would have to be dismantled to get it into my workshop and NOISE. Even on a large traction engine most of the bits are small diameter and turned at moderate speed. The BH600 in the showroom was very noisey. The GH1224VS was impressively quiet at speed. Being slightly narrower than the BH600 can go into my workshop in one piece but I am not sure I want 1/2 tonne on the floor. My big fear is that the 18" capability is unusable and I will go for a lot of trouble for nothing.

Due to my scepticism and the large diameter capability of the GH122VS and the noise of the BH600 I am resigned to farming out the larger stuff and hence I am looking at slightly smaller lathes that can turn 99% of a 6" traction engine.

[houstonceng]

One of the guys in my ME Soc. has one of these "BF600 type" and he said that the 18" was a bit of "smoke and mirrors". For a start, he cant get the tool mounted such that he can turn the 18" and reach the centre if he was facing something that large and, if he mounts the tool such that he can reach the centre, he can't get it out to the larger radii.

Secondly, the power/torque at low revs is inadequate.

I've got a Warco 1327GH (Taiwanese) bought in 1997. It's no longer available and I suspect it's been superceeded by the GH1224VS, or equivalent, Chinese made lathes. The only mistake I made was buying it with a single-phase motor. 2hp single-phase motors aren't that quite and they "cog" so, the motor, being mounted on the head casting (not resiliant mounted) caused vibes and paterning on the work-piece.

I rebuilt to a 3-phase, 2hp motor + inverter and, so far, have nothing but praise for the combo. I use an inverter range of 50% to 200% speed vs the 50Hz circa 1450RPM on the motor. That, plus 8 GH speeds is OK.

[jasonb]

Julia, I had a 280V-F delivered last week, I was a bit worried by the lowest speed of 125rpm quoted in the catalogue, this is infact a misprint (speed for the belt drive lathe). There was not one on display but they got one out of the warehouse for me, openened the crate, plugged it in and left me to play. It was very quiet and the lowest indicated speed was 46rpm. Like you I would have liked the larger capacity of the next size up but at double the weight I could see the end of the shed sinking into my clay soil.

One of the first jobs is to turn the 9" flywheel for my Fowler, probably be a week or so until I get it all set up and can report back.

I also have an X3 clone mill with variable speed and have not had problems with that being underpowered.

Are you going to be at Guildford, if so I'll come and chat lathes with you, I've got a nice Emco for sale as well

Jason

[Julia]

Jason
Unfortunately I can't go to Guildford because it clashes with the Kent Show to which I am taking my engine. This is a shame as Guildford is one of the best all round events in the ME calendar. May be next year the show will be able to nab a better date.

I will be very interested to know how you get on with the fly wheel. If you succeed even with difficulty I think I would be sold.

[jasonb]

I'll keep you posted.
PM also sent.

Jason

[jasonb]

To answer your first question they have a DC motor, 1Kw in the case of the WM280V-F which has a two step pully giving the 50-950 and 110-2000 ranges.

I was not so worried about the torque but the lowest speed, 100rpm on an 18" CI flywheel is way too fast. With carbide tooling the 46rpm on the 280 should be just right for the 9" flywheel and final drive gears.

JAson

[Steve M. W]

Julie

Which 6" Traction engine and who's drawings, and are you going to do a web diary.

Steve

[Julia]

Steve
6" GM from Little Samson, probably without a diary.

[circlip]

Houstonc, is your rebuild a comercial inverter (VFD)?
Regards Ian.

[steam4ian]

G'day Julia

I only have experience with the 7x12 variable speed lathes. Mine will run down to 50 RPM...... BUT, as the speed falls the cooling of the motor falls as she inverse square (or is it inverse cube) of the speed. However the heating of the motor is proportional to the square of the current, read square of the torque. Just when you need the high torque you have no cooling. I just about cooked the motor on my little lathe. (Note the same problem occurs with the ac type VS drives.)

A number of 7x12 owners have put in extra speed reduction by either changing the motor pulley or putting in a lay shaft. Whilst 1/3 HP would be fine for a 7x12 lathe with stepped pulleys and back-gear I would suggest that at least 1 HP would be right for 7x12 VS lathe.

Adding a fixed speed fan to provide motor cooling would be a part solution; this is used in industry where VS motor are used, see crane hoists, traction motors, rolling mill motors etc.

BTW the variable speed is a great help; just wind up the speed until the chips go blue!

Regards,
Ian

[houstonceng]

Jul 8, 2008 8:35:42 GMT @circlip said:

Houstonc, is your rebuild a comercial inverter (VFD)?
Regards Ian.

Yes. Ian

Life's too short to design and build a 1.5kW Inverter (VFD) that I could buy from flea-bay, brand-new in original packaging for 1/6th the price of some being sold via ME and by some well known suppliers.

Had to add another contactor and, obviously, a 3-phase motor. I did it all for less than £200. Warco quoted me £600 a few years ago.

[circlip]

When this one reared its head,I was suprised you hadn't jumped in earlier Andy, anything bigger than, and probably including a Unimat too, is going to fall over due to lack of torque offered with a"Speed" controller.
Regards Ian

[houstonceng]

Jul 9, 2008 12:47:01 GMT @circlip said:

When this one reared its head,I was suprised you hadn't jumped in earlier Andy, anything bigger than, and probably including a Unimat too, is going to fall over due to lack of torque offered with a"Speed" controller.
Regards Ian

Depends on the design of the "Speed Controller" - or VFD come to that. Some can compensate to give constant Torque at low speed and constant Power at high speed.

Anyway, I didn't - initially - see this as a VFD question so I dodn't "jump in" as you thought I would - and I like to keep some surprises for you now and again.

[russell]

I've no experience of him but I note that the same lathe as the Warco one is currently being advertised by an Ebay seller at £985. A significant saving. However I do have experience of Warco and have always found their service to be good.

Russell.