Need Some Advice Please!

I may be able to get an original 220V 3 phase motor 3/4 HP for my lathe BUT I don't have three phase what would be best to do in this case? Do I just buy a VFD and run it off of it OR do I get a NEW 220V 3 phase motor which is cheaper and run it with a VFD? And see if I get one with a shaft the same diameter as my old one for the cogged pulley. What would be best to do?
 
From what you said, I assume your current motor is a single phase motor and you want to replace it with a 3 phase so you can run off of a VFD. Most low HP VFDs will run off of single phase, and all of them output 3 phase.

I guess I would use any 3 phase motor that had the same frame size, and get a VFD to match. Motors are normally designated by frame size and HP or KW, so any given frame number would have the same shaft size It really doesn't matter if you have the factory motor or not.
 
Wheresmywrench? said:
I may need to replace the motor on my Maximat V10-P lathe. the original motor is 1hp reversible, 2 speed. What are my options, as I need to control the speed and want forward/reverse. Would like 220/240 V I don't have 3 phase available.
Click to expand...
Have you considered replacing with a treadmill motor? I've done it for my drill press, lathe, and mill. (1.5, 3, 3 HP respectively). Treadmills come with speed control and even tach feedback that keeps the speed constant regardless of load. The gist of it is that the standard 115 VAC power gets converted to pulsing DC, and the length of the pulses is controlled electronically to set the speed. You get great torque even at very low rpm (I can wind pretty stiff springs on my lathe), and reversal takes a simple DPDT switch. And there's a great safety bonus: you can throw in another switch (SPDT) and a resistor and get electrical braking - I can stop my lathe in less than 1 second just by shifting my weight off a footswitch. You can run 2 HP on a 15 amp circuit, 3 on a 20.
The mounting issues are about the same as any other motor adaptation - figure on making a custom bracket and some finagling with pulleys.
If you don't want to fool with the treadmill control panel (they can be big and full of functions you don't want), you can substitute a simple potentiometer ($3). You lose the auto speed control, but given the HP available, you probably won't need it.
I put an ad on Craigslist and paid from $0 to $50 per unit. Some people were happy to have me haul it away for free.
 
My question is what is the motor not doing that makes you think that its going south on you. Outside of bearings going bad there is very little that can go bad on a quality motor. You could be having issues with the contactors or wiring and not the motor.

Jim Nunn
 
OK the motor uses a run capacitor and the previous owner installed the wrong size cap on the lathe 20 uF when it should have been 12uF. At first the lathe worked fine until it started to kick out the overload on the lathe. Now it kicks out as soon as you turn it on. Now I took the motor to a rewinder and he tested the circuits and they are all intact. Because this is a European made he would not put power to it due to not knowing what the color code was. Depending on the age of the motor there are two different color codes. So I have brought the motor home and will hookup the motor with the proper capacitor and see what happens. There was no smoke or smell when the motor started kicking out.
 
If you can get a vfd that can do vector control you will get better torque characteristics compared to a standard drive and not all three phase two speed motors can take a drive as you must be able to connect the motor in delta
 
Well there's been a new development with my motor. Just had a conversation with a member of the V10 lathe Yahoo group. And He has the same motor I have and went through the same thing I am. It turns out that these are in fact 3 phase motors. Apparently at an some point Emco in there mighty wisdom decided instead of using real single phase 220V motors they would put 20uF caps on 3 phase motors and ship them as single phase to the US in the US destined lathes. My machine came from Boston. So now I have to completely rewire my control box for a 3 phase setup!!!!
 
It looks like you might have a couple of options. You certainly want to have your machine tools up and running. One suggestion is to take the motor back to the motor shop and have the technician evaluate the motor type. For instance, is it really a "3 phase induction motor" or is it a split-phase capacitive start motor? My Maximat Standard has this type of motor and you can hear the switch contacts release as the motor is shutoff.

In the short term, you might purchase a replacement capacitor and have your Maximat operating again. In the long term, you could consider a 3 phase motor replacement or if you truly have a 3 phase induction motor, purchase a VFD controller. My favorite for this size motor range is Model KBVF-24D from KB Electronics, Coral Springs, FL. These are well made, a mature technology, and easy to implement. I have purchased a total of 3 used ones on eBay over several years from $80-$120 USD per each. One of these powers my bandsaw using a standard 3 phase induction motor and a second will be powering a 1968 South Bend bench lathe. These controllers can be jumpered to operate on 120 or 220 VAC, 60 or 50 Hz single phase and output 3 phase. You can also control the ramping speed of the motor at startup (with a potentiometer setting) so that the motor doesn't just bang hard as it starts.
 
You must log in or register to reply here.
Back
Top