I have another question about the M head that I now own. It is wired 3 phase, with a 1/2 hp drive motor, and a 1/8 hp for the power feed. I know very little about 3 phase wiring, so I have decided to take everything [motors, boxes, wire, switches, and the new VFD converter that I bought], to a local electric motor shop. They said that they could go through the wiring and get me set up, and I trust them. My question is, how do I want the mill motors wired? They said that the converter box I bought may be able to run both motors, but do I want both the vary speed at the same time? Or the drive motor variable and the power feed constant? The drive constant and power feed variable? The drive is variable now by changing a V belt position, and the power feed is variable via a gear positioning lever. It is also reversable on the gearbox. I am sure that I will be asked how I want this to work and, as I have very little experience with a mill I am not sure how to answer. Any suggestions would be appreciated.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
VFD Questions
- Thread starter todd281
- Start date
- Joined
- Feb 2, 2013
- Messages
- 3,963
I have run motors from the 1920’s off a vfd.
If you stay in the 30 to 90 Hz envelope for short periods of time , there’s little chance of major complications.
Over or under excited windings are insufficiently cooled by the OEM fan if the motor runs too slow or too fast for extended periods of time
If you stay in the 30 to 90 Hz envelope for short periods of time , there’s little chance of major complications.
Over or under excited windings are insufficiently cooled by the OEM fan if the motor runs too slow or too fast for extended periods of time
Last edited:
- Joined
- Feb 2, 2013
- Messages
- 3,963
I would be partial to running the spindle with the VFD, for variable speed and run a small static converter circuit for the table drive that would operate from single phase input and keep the OEM operation.
Technically, a 3 phase drive motor could operate with a sufficient capacitor between phases and being supplied single phase input
As for rotary phase converter, all I have seen are out of my price range. I was also thinking that the drive/spindle motor should be run through the VFD. If I need to purchase another converter to drive the power feed that would not be the end of the earth. Maybe I am overthinking this.
- Joined
- Jan 31, 2016
- Messages
- 12,901
Bainbridge NY ? 
I got a ticket up there a few years back and broke down there a few times . Ended up in the station right off 88 . Had to walk down to the auto parts store across the river and back to the station and install an alternator in the Suburban . A few of us on here have property a little north of you . 
I got a ticket up there a few years back and broke down there a few times . Ended up in the station right off 88 . Had to walk down to the auto parts store across the river and back to the station and install an alternator in the Suburban . A few of us on here have property a little north of you . It's good to hear that there are others nearby. I have been here in Bainbridge over 30 years. Retired now and seem to have more to do than ever. I have a Shelon 13-inch lathe and have wanted a mill for some time now. I got this M head, sold to me as being single phase. It was already unwired when I picked it up. I called the seller, and he said he noticed the VFD on the wall after he sold it to me. I got it for a steal, and he gave me quite allot of other stuff so I can't complain. It looks like I will have to go with two converters for now, maybe change it in the future. Right now I started the cleaning and inspection of the mill. That has turned into strip and repaint. It's going to take some time for the shop to go through the motor and wiring so I might as well.
- Joined
- Jun 12, 2014
- Messages
- 5,074
Drives tend to be single phase, so I would check the drive before you decided to connect it to a VFD. They are typically DC motors. The main mill motor would be directly wired to the VFD motor terminals and then you can use the VFD low voltage inputs to control the mill motor. With an older smaller motor you do not want to push it too hard, so keep the carrier frequency at around 8kHz, speed range 30-75Hz, use normal duty (ND) settings as opposed to heavy duty (HD). You can either use what is called 2 wire control which requires and ON-OFF-ON sustained switch for FOR-STOP-REV, or 3 wire control which uses a momentary NO switch to start for run, momentary NC switch for stop and a sustained switch for reverse. I prefer the latter.