Thread: "Upgrading" a lathe to 3 phase?

I have been gifted a Hafco AL336. It has a 2HP 240v motor is working OK. The previous owner wants to swap its motor with a 3 phase motor in a drill press.

The lathe electronics:
Screen Shot 2020-06-06 at 9.19.30 pm.jpg


will need some change for 3 phase – 3 pole emergency stop, maybe upgrade the twin 3 pole contactors, seperate 240v for coolant pump and 24v indicator lights, relays, et c.

I'm starting to think;

1. Installing a VFD would be much easier, though more expensive
2. I might not actually use the extra power/torque a 3 phase could provide
3. Just getting a single phase motor for the drill press would be easiest

Thoughts?

Originally Posted by nigelpearson

will need some change for 3 phase – 3 pole emergency stop, maybe upgrade the twin 3 pole contactors, seperate 240v for coolant pump and 24v indicator lights, relays, et c.

I'm starting to think;

1. Installing a VFD would be much easier, though more expensive
2. I might not actually use the extra power/torque a 3 phase could provide
3. Just getting a single phase motor for the drill press would be easiest

Thoughts?

By the time you get a 3P plug, contractor and 3 pole emergency etc you're going to be up round the Half way mark for a VFD.

Buy the previous owner a single phase motor for the drill press and take the 3ph one off his hands.
Run the lathe as-is, and if you feel the need to put the 3ph motor on it later you’ve got it there.
Also, the drill press motor is probably less than 2hp....

Steve

Having a 336 which I changed the motor out of.

If motor is working I wouldn't dick with it. For starters getting another one to fit, bolt patterns, possibly altering splash guard etc...

Been there - mines working fine. Not a 2 minute job.

Of course the costings of 3 ph contactor etc.. has already been stated.

Originally Posted by BobL

By the time you get a 3P plug, contractor and 3 pole emergency etc you're going to be up round the Half way mark for a VFD.

Valid point.

I do have spare DIN mini-contactors, but a 3 pole stop to fit through the front panel will be a challenge.
Although, if I went the VFD route, not sure if a "soft" emergency stop would be good enough?

Originally Posted by nigelpearson

Valid point.

I do have spare DIN mini-contactors, but a 3 pole stop to fit through the front panel will be a challenge.
Although, if I went the VFD route, not sure if a "soft" emergency stop would be good enough?

Depending on the VFD you could set up one of the aux inputs to run a smaller switch (less contacts required) that sends it to almost instant brake using a resistor.

If it makes you feel better, I don't have E-stops on my mill, lathe, drill press.. I did fit one to my Mrs though, I found the uncontrollable feedback loop of gibberish took off a bit quick at times and needed a quick stop..

Originally Posted by racingtadpole

Depending on the VFD you could set up one of the aux inputs to run a smaller switch (less contacts required) that sends it to almost instant brake using a resistor.

If it makes you feel better, I don't have E-stops on my mill, lathe, drill press.. I did fit one to my Mrs though, I found the uncontrollable feedback loop of gibberish took off a bit quick at times and needed a quick stop..

I have E-stop switches to the SP 240V supply input to the VFD - that stops the motor on my lathes and DP in about 1s compared to the 3s deceleration set in the parameters. It's not advised to use this as a regular stopping mechanism but for emergency use its better than nothing. Some VFDs specifically indicates to avoid doing this but VFDs have to be able to cope with power supply outages so its no different.

I would not swap motors unless the power rating, motor shaft diameter, frame size and rpm are very similar.
Unless the drill press is very large, you would not need a 2HP motor for it. I have a half horsepower motor on my drill
press which is fine. A 2HP motor simply would not fit and would be too heavy.

You could upgrade the lathe to a 3 phase motor. I am not sure it would make a lot of difference to the performance of the lathe.
If you have 3 phase power nearby, you could start with that and add a VFD later if required.
For 240 volt accessories, you can run a 415 to 240 volt transformer. This is what I have on my lathe.

Hope this helps.
regards,
Paul

Paul is right, the drill press is only 1/2HP (despite being a large motor casting).
Not much good on anything but a Hercus


I will look around for a cheap 400W 240V motor.