Repowering a Lathe

[drec]

About 15 years ago, I had a ShopTask lathe/mill combo. There was an article on using a treadmill type motor on them; which I purchased at Surplus Center. I never did the conversion and sold the ShopTask. Then several years ago, I used one of the motors and controller on my Dalton lathe. The motor that I used, has a range from 0 to 6000 RPM's. So through some pulleys, I've been able to make it usable for the bushing lathe.

I've used VFD's on other tools, and I've heard (fwiw) that you don't want to run them very long at speeds lower than 30hz because of potential heating problems.

 

[cuseguy]

About 15 years ago, I had a ShopTask lathe/mill combo. There was an article on using a treadmill type motor on them; which I purchased at Surplus Center. I never did the conversion and sold the ShopTask. Then several years ago, I used one of the motors and controller on my Dalton lathe. The motor that I used, has a range from 0 to 6000 RPM's. So through some pulleys, I've been able to make it usable for the bushing lathe.

I've used VFD's on other tools, and I've heard (fwiw) that you don't want to run them very long at speeds lower than 30hz because of potential heating problems.

I think the low frequency overheating issue is a bit overblown personally. I have a Hardinge DV59 with a Teco VFD/Baldor 1.5hp and I run it all the time at 25-30mhz to get the low speeds I need for many 2nd ops and the motor never even gets warm to the touch after constant use of 30-60 minute cycles. I also have a Grizzly lathe with the same model Teco 7300EV VFD that I constantly single point thread with, usually at about 25mhz. Same thing, no heat issues. I'm sure if I ran down in sub 20mhz range, it may overheat in time, but that frequency range has such a lack of torque and poor usability that I can't see much use of prolonged use in that range. That would be one of the few times I would switch pulleys to gain back the torque. And if someone did find a need to run in the sub 20mhz range, an easy fix is wiring a $10 PC fan in to stop the heat issues

 

[drec]

I think the low frequency overheating issue is a bit overblown personally. I have a Hardinge DV59 with a Teco VFD/Baldor 1.5hp and I run it all the time at 25-30mhz to get the low speeds I need for many 2nd ops and the motor never even gets warm to the touch after constant use of 30-60 minute cycles. I also have a Grizzly lathe with the same model Teco 7300EV VFD that I constantly single point thread with, usually at about 25mhz. Same thing, no heat issues. I'm sure if I ran down in sub 20mhz range, it may overheat in time, but that frequency range has such a lack of torque and poor usability that I can't see much use of prolonged use in that range. That would be one of the few times I would switch pulleys to gain back the torque. And if someone did find a need to run in the sub 20mhz range, an easy fix is wiring a $10 PC fan in to stop the heat issues

Thanks for sharing your experience. I suppose that it would also depend on how much load is being put on the motor at the lower speed. If you are finding that you are in the lower speeds most of the time, a pulley change might be worthwhile.