Thread: How much power?

What is the HP of the current single phase motor? can you not just swap like for like?

I would take the opportunity and go to a 2HP motor. And no I don't think its excessive

On a mini lathe, 372w (1/2HP) is enough, given the physical limitations of the lathe.

I would expect a 12'' swing lathe would need at least 1 hp effective power. Dont know how that translates using a vfd however. My 12'' swing lathe is 1hp belt drive and I can stall that at times.
Regards
John

Our original Nova Mercury wood lathe was 1/2 hp DC variable speed. OK for spindle work but would stall on even moderate cuts turning 150-200mm bowls. That was both inboard and outboard, 3/8" & 1/2" Hamlet bowl gouges with a pretty standard grind & sharp, plus stepping down the belts for max torque! DC VS's aren't renowned for low down torque performance either.

When the DC VS unit died, and Teknatool were very unhelpful with spares (they couldn't give a rats imho, but that is another story), we replaced the whole drive setup with one of SE QLD Woodturning Supplies 1 hp VS kits, transformed the lathe but a relatively noisy upgrade compared to OEM. It also required modification of the motor spindle to match the lower pulley shaft bore dia.

Depends upon what the turner wants to do, but I would suggest 1hp min. Also consider the expected duty cycle. There is a vast difference between the VL100 /150's all day everyday type duty cycle and the lower price point midi lathes on the market. But you pay for it!

If the lathe is to be used every day on larger projects then go big! If it's only going to be used for say pen turning then 1/2hp will suffice imo.

Look at what the VL100's at TAWA have done over the many years they have been there - all 1 hp iirc.

I'm not sure what model the Woodfast lathe is, as it's described as a middy lathe. I have recently done exactly what is proposed to my MC908s using a Conon motor and VFD and it's been a huge success. The motor is a 1.5HP with a BD600 series VFD. To answer your question, I would fit the biggest motor possible, and consider a 0.5HP motor (hooked to a VFD) as not powerful enough. But, unless you are prepared to make several changes, check out the frame sizes of the various HP motors and the physical size to make sure it will fit. If you would like the frame and motor sizes for each model (and there are heaps of them) just send me a a pm and I'll get it to you. Finally, I know there are cheaper units available but I was happy to pay more to deal with a local supplier - and the Conon service and help was worth it!
Cheers, Gary

I recently rebuilt a Woodfast 102SB lathe that had been converted from three-phase with a 1/2HP . One of the issues with the Woodfast is the motor area is designed for a 3 phase and so has less room. It took awhile to find a sized single phase motor, in the end picked up one for Hare n Forbes, you really cant have too much power but the physical restraint of the lathe often dictates. As such on a previous Woodfast 400 I went back to three phase and installed 1.2kw motor and of course a VFD all due to motor bay size. One thing you may need to consider is keeping the stepped pulleys to offset the torque losses with frequency speed control.So I think 1/2hp will work but it wont work very well this will be noticed very quickly with a VFD, better off with 1hp or greater.

Almost 10 years ago I started playing round with electric motors and VFDs I made myself a small dyno that could measure the HP output of 3P motor running off VFDs.
There's a long tread about this in the MW forum for anyone that is interested. VSD power tests - Page 6

The result of all this was a "VFD for Newbies" document available in the sticky post in the electronics forums
VFDs for Newbies

There is also an extensive thread of examples of VFD instals.
VFD install summaries

Thanks for everyone's replies. It currently has a 1/2 HP single phase motor and that does the job for him. I got to check the exact measurements today and only the 1/2 HP three phase motor will fit, the 3/4HP is just too tight to run the risk of experimentation. So I have given him this info and let him make the decision whether to go ahead.
He does not want a bigger motor hanging under the lathe, he wants it as it is.
Thanks,
Rgds,
Crocy.

Some years ago, I bought a GPW Midi lathe, it had a 1/2 hp single phase motor.
I repowered it with a 1 hp 3ph and a VFD. I used the Vicmarc 3 step pulleys. They always stay on the middle step as this lathe is pretty much only used for pen turning.
I have made some pepper mills and small bowls on it, but that really tested its abilities, I would not want to go any smaller than 1hp unless pens is all that would be turned.
If I had to do it again, I would go bigger. Though at the time , the 1hp motor cost me nothing, as it was sitting in the shed doing nothing, it came out of a jointer that I repowered to use single phase.

My first lathe was a Delta 12"x36. It had a 3/4hp motor and I never overtaxed it. I used it for a lot of production work and burned out a lot of bearings but the motor was always strong. The caveat to that is it had the old expanding pully system so the motor was always at max rpm.

You plan to use a VFD therefore you're going to need a much larger motor at lower rpms, unless you have step down pullies to account for the low rpms. That's the first thing you need to look into. If it doesn't have at least a 3 step pully, you'll need to see if you can fit one or put the largest motor in that will fit.