Help : DIY VSD/Inverter Drive

Dave Keep the 3 phase motor. If you go for a VFD, you can only run 1 machine from it; if there are any electrical components, apart from the motor, in the lathe, you'll have to make sure they're wired directly to the mains supply and not the VFD output. Make sure the motor can be wired for 230V (it should be marked 230 / 415V or similar), typically it will need the links set to make it delta wound as you only get 230V 3 phase from the VFD. The big advantage of the VFD is the speed control you can get. You may want to install a remote potentiometer for speed control plus stop and start switches and, if you want to adhere to the law, a mains filter should be fitted close to the VFD input to reduce EMC. Apart from that, it's a matter of programming but you will need to know as much as possible about the motor to program the overload protection in the VFD (easy if it's still in production). Martin

Dave, Option 3 will only work if the motors is dual wound 240/440 volt. If the motor has any age on it it may only be delta wound. Take a look at the name plate or the terminal box to see if it's a 6 wire jobbie.

All the current batch of invertors are suitable but beware some need an extra programming panel that jacks the price up. Mitsubishi is good at this. That one you link to is fine and a stand alone but take a look at

-- Regards,

John Stevenson Nottingham, England.

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John,

Thanks, The lahte is afaik fitted with the original motor, so Ill chec that for suitability first. Its good to know someone has been down thi path first :)

Martin, im aware I can only run 1 machine for 1 drive, currently I have no phase machines, and a suitably size rotary convertor is approx 2x th price of a drive, so I fugured that as long as i only have lathe an mill (dont have either yet) on 3 phase its no price difference... I assume RS will have suitable mains filters.

regarding star/delta winding it will be obvious if the motor i

I pick the lathe up first weekend in march, so thanks for your help and Ill ask some more if nessescary when i get it.

Dav

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Hello Dave,

I have a Transwave static phase converter which I used to drive a 2HP Harrison vertical mill. I got a bigger lathe and an even bigger converter so this one is surplus to requirements... (I'm in north Hampshire BTW - it's kind of heavy!)

Contact me if you're interested - jez(AT)jez(HYPHEN)nikki(dot)net.

Cheers, Jez.

Having just fitted my Myford lathe with a 3ph motor & a VFD (VSD), I can strongly recommend option 3:

- 1ph motors will always hum, vibrating the lathe body and leaving a poorer finish on work. 3ph motors aren't silent but they vibrate less, so you'll get a noticeably better finish.

- 3ph converters are fine but bulky; I run a 3hp mill on one and it just takes up floor space. It starts 'hard' too, dimming the lights & giving me this urge to cackle maniacally "Live! Live, my beauty!"

- All the VFDs I've seen make the motor whine a bit - more intrusive than 50hz hum. Given the units are cheaper, can be mounted in the lathe cabinet, let you vary speed during a cut and have bells & whistles like soft-start, they're a great option.

HTH Guy

If you are happy putting a controller in it's own box, I have used KB controllers with success, their KBF 23D would probably be suitable. £ 79 from JB marketing tel 01323 870066. I suspect there are more modern units which will be better... Come in John :-).