3 ph -VFD Powermatic 90

[William C Rogers]

I had posted a while back regarding lathe swing on my PM 90. I decided to raise my lathe 3" giving me a 18" swing instead of buying a new lathe. I pretty much have all that figured out thanks to Roy Turbett.
When I first got this lathe it was 3ph which I changed to single phase keeping the 1hp the same. The way I did this was bypassing the micro switch and using a 120/240 relay, using the existing start/stop switch. I put the relay in the box that use to contain the 3ph heaters. From the outside the lathe looks the same as in 1973. This lathe is a reeves drive with a speed range of 330-2100. I will try it with the existing 1hp motor, but I may need/want to go to 2hp. It would be easy to just change the motor to a single phase 2hp using what I have.
However, is 330 slow enough? I know nothing about 3ph and VFD. If I would want to go this route how does all this connect i.e does the VFD go to the power and the motor connect to the VFD? What about the reeves drive, do I remove it and figure out a way to connect?
Remember I know nothing how using 3ph would work.

[Brian Myers]

I would think you are going to find that 1hp is not enough if you turn past 12" and especially when you get to the max your lathe is now. , 2hp would definitely be a nice upgrade. You would end up getting a VFD for single phase input so your your house current goes into the VFD and outputs 3ph to the 3ph motor. The VFD would also allow you to slow down your speed when you wanted. If you kept the reeves drive intact then you would have a series of speed ranges with the original speed as the max and the VFD allowing you to slow it down further. I am looking to eventually raise the spindle on my Yates J170 from 12 to 16" and already have 1.5hp 3 ph motor running off of a VFD. In my case due to head stock casting issues I am getting rid of the original casting and putting the spindle in a pair of heavy duty pillow blocks sitting on riser blocks attached to the original base casting. Currently a work in progress just to get the lathe back to running shape then on to 16" later down the road.

[Doug Ladendorf]

Yes, your house 240v current goes to the VFD, which converts it to three phase. It is important that you go straight to the motor from the VFD with nothing in between. You can connect switches to the VFD for stop/start, reverse and speed. Many people are putting these controls on a pendant they can move to a convenient and safe spot as they turn. You would keep the reeves drive and use them together.

Doug

[john taliaferro]

I can get 2 or 3 rpm to spray finish , or just to admire the wood .

[Dennis Ford]

The 1 hp motor was plenty for 12 inch swing and you might be satisfied with with it at 18 inch swing but I doubt it. Heavy cuts will bog it down. The minimum RPM will be a problem if you start with large natural edge blocks. A vfd with 3ph motor would be a nice upgrade.