Thread: Testing a CNC Mill with a VFD?

I'm entertaining the purchase of a ~ 20 year old Matsuura CNC bed mill. It is not currently connected to power and cannot be where it is at. I would really like to see and inspect it under power before I committed to buying it. The price he's asking makes for a gonga deal.

So without an RPC to take up there with me, I was wondering if I connected it up to a 3hp VFD, would this at least allow me to run and test out the basics without powering up the main spindle motor? Would I be able to run the axis servos in jog mode? boot up the software, and see the control display and run some dry (no spindle turning) basic functions?


Thanks...

Mike

(I cross posted this on the VFD forum as well)

Quite sure you have to run a RPC and a good one at that.

Polar, can you explain further as to why my idea would not work? Again, I'm not wishing to power the spindle motor, which is I think 7.5hp, but just the electronics and the axis servos.

Thanks...

Can you rent a three phase generator? You only need 15kVA and this would allow you to do full operation testing.

As far as I understand CNC power requirements and VFDs I think you might run into problems using a VFD. The VFD is designed to be connected to a motor which is an inductive load while a CNC is more of a capacitative load as most of the power goes through a rectifier bank and charges big capacitors on the DC buss.

Hmmm, a three phase generator. I'll have to call around. I would only need it for a couple of hours... Thanks

You can't run electronics on a vfd. You can try, and it might work but you run a very high risk of frying something. There is a pretty comprehensive thread on the subject quite recently.