I just dug this out of my pile and was wondering if this would be a good drive for a lathe?
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I just dug this out of my pile and was wondering if this would be a good drive for a lathe?
can't upload for some reason, its a yaskawa R88M-M700012-b motor and the matching R88D-MT20 drive
Depends on the motor spec's and the size of the lathe, along with your expectations of the cutting performance. But a servo motor makes a great spindle motor for a lathe. A few weeks ago I replaced my lathe 7.5kW spindle motor with a 7.5kW servo motor and it works great, actually better performance than the original. The max RPM is now reduced to 3500 vs. the original 5000, but I never have ran it over 2500 anyway.
Jim, the motor is huge, its about 16" long and a Nema 42, but it is only 700 watts and 1200 rpm. I have it running with mach 3 on Step + Dir. Do you understand why it is so large and only 700 watts?
It does seem large for 750W. I didn't look up the spec's but that sounds like a high torque (for it's size) motor. 1200 RPM is the rated RPM, most servos have a absolute max RPM that is 2X the rated RPM, not sure if that is the case here.
Most servo motors have a flat torque curve from 0 up to the rated RPM, so are really well suited for a lathe spindle. A high torque 750W would be suitable for smaller benchtop lathes, maybe up to 12 inch swing or so, either with 1:1 or a 1.5:1 timing belt reduction. This would really depend on what your normal cutting parameters are.
Look up the spec's on the motor, and compare the torque curve to the torque of a standard 750W (1 HP) induction motor to really see where you are at. I would expect that the performance would be better than a standard induction motor.
I've been looking at these servo motors for myself:
https://www.ebay.com/itm/18466227706...Cclp%3A2047675
10nm of torque for a 1hp motor is probably enough to get away without gears on a small lathe or mill. They seem fairly cheap considering they come with the drive.
They also offer a 2hp version but they still advertise 10nm of torque so I guess it's only better at higher speeds. Both look fairly light and compact for what they are.
What makes a motor good for a spindle besides being rated for continuous duty and having enough torque and speed for the application?
Most of the load is taken by the spindle cartridge. I guess some motors have a better "heavy duty" cast iron case and a larger shaft.
But, if you have one sitting on the shelf unused, maybe just try it and live with it if it breaks...
Those motors look nice, Goemon, but the description says theres no way to control them externally, yet. Yeah, I will probably just give this thing a try. I have one of the ebay 8.75 x 29.5 inch mini lathes, or I just ordered one. Who knows, if it runs good, maybe i'll leave it stock and just put an optic index on it.
What do you mean? They come with a stand-alone controller. The seller also offers a kit for a mini lathe.Quote:
Originally Posted by Halfnutz
The first issue to correct on a mini lathe IMO is plastic gears. No point in upgrading a motor if you just strip the gears when you try and use the extra power.
Goeman, Theres no way to control it from a computer or controller it says, but honestly you could always hijack the potentiometer with an analog signal, its probably +- 10V. No big deal.
Where does it say that?Quote:
Originally Posted by Halfnutz
The listing says it comes with a controller with internal speed control allowing it to be set anywhere from 300-4500 rpm (for the 1hp model) and 300-3500rpm for the 2hp one (in 100 rpm increments).
Nobody would buy a servo motor that can't be controlled in any way...
If you are talking about adjusting speed via the cnc software (for ATC) that's different and would require a mod.
But, turning it on and setting the speed is done with it's stand-alone controller.