Spindle Speed Control

[bill south]

I recencly posted a request for help finding a replacment motor for my lathemaster mill zay series from Bob. In doing a little research and a lot of reading from the great minds on this site, I think my question should have been for information on what an optimimum setup would be for a home cnc benchtop mill which would include the new motor (2hp, 3phase(?)), a phase converter or VFD, speed control, and hardware interface unit for mach 3. I'm planning to upgrade to a 3000 rpm motor. Will anyone knowledgable in this please share his thoughts!! :>}
billyjack

[BobWarfield]

Industrial Hobbies are related to the ZAY series. Their site has an excellent article on fitting a new motor with VFD. Give their article a read:

http://www.industrialhobbies.com/

It's in the "Product Instructions" link on the left. I was able to buy the Leeson motor they specify on Amazon. I got a VFD from www.driveswarehouse.com at a great price too.

Best,

BW

[ChrisJ]

Hi Billyjack,

I am not very knowledgable on the subject but and I am a little informed.

I am not sure your Lathemaster can handle 3000 RPM. The Industrial Hobbies mill was ordered with hardened gears in order to run the mill at the higher RPM's. I do not think that the Lathemaster has the hardened gears, but you may want to verify.

My suggestion would be to get the 1800 RPM motor from Leeson. You can overclock the motor to 90 hertz using a VFD, which will give you 1.5x nameplate. You still should verify with Lathemaster on the recommended RPM limit for this mill. Plus this motor selection will have more torque at the slower speeds than a 3600 RPM motor will have. For instance a 2hp 3600 rpm motor will have 6ft-lbs of torque (I think), but when running that motor at 1800 rpm you will only get 3ft-lbs of torque. The torque is needed more at the slower speeds than at the higher speeds.

I believe a TENV constant torque motor is a better motor for this application, however the frame of the TENV motor is not compatible with the mill head and it would require some ingenuity to adapt this style of motor with that mill. The reason I like this motor is because you can achieve constant torque from 0 rpm all the way up to nameplate rpm, without any concerns of overheating the motor when running it at slow speeds. Plus these motors can be overclocked to 180 hz, 3x's nameplate. This provides for the most flexibility.

With regards to interfacing a 3 phase motor with Mach, I would use a VFD and a spindle board. I have a GS2 VFD from automationdirect.com. You can use a spindle board from Campbelldesigns.com to interface Mach with the VFD. There are probably other spindle control boards out there, I just don't know of any.

Perhaps the best of the options for retrofitting this type of mill would be to eliminate the gears and adapt it to be a belt drive. I hear that Industrial hobbies is working on documentation (for sale) for this specific retrofit. In this scenario, no more gears to worry about.

Chris