Fitting a VFD to a Bridgeport mill

[zoeper]

Can anyone fill me in on the pro's and conns of fitting a bridgeport type mill with a VFD?
I suppose that low speed torque would be sacrifised, but how feasable is it?
My controll (Anilam crusager G)outputs a analog voltage to controll speed and at present it is hooked up to a motor and "controller" board that changes the handwheel on the head. it is slow to opperate and only acurate/ repeatable to about 30% of the programmed value. The analog signal should be easy to hook up to the VFD though.

Thank you
Pieter

[zoeper]

Some of the gains should be the ability to ramp up the speed and to brake the motor without mechanical means. (i like this one)
and a simplified drive train doing away with the variable pulley system. This might make higher speeds possible.
Any comments welcome
P

[TOTALLYRC]

Originally Posted by zoeper Can anyone fill me in on the pro's and conns of fitting a bridgeport type mill with a VFD? I suppose that low speed torque would be sacrifised, but how feasable is it? My controll (Anilam crusager G)outputs a analog voltage to controll speed and at present it is hooked up to a motor and "controller" board that changes the handwheel on the head. it is slow to opperate and only acurate/ repeatable to about 30% of the programmed value. The analog signal should be easy to hook up to the VFD though. Thank you Pieter

I have a hitachi sj200 sensorless vector drive hooked to my bport btc-1.
It came from the factory with an early vfd and a 2 speed gear box along with a 3hp motor. The sensorless vector helps with the low speed torque and is the way to go in my opinion. I am working on integrating the 2 speed to be controlled by Mach3. As it is now, If I have to go into low gear, I have to do it manually.

See my build log here. http://www.cnczone.com/forums/showthread.php?t=66994

There has been some discussion that the gear spread is too wide to work properly but so far it is working well for me, not that I have done much maching with it yet.

[HimyKabibble]

Originally Posted by zoeper Can anyone fill me in on the pro's and conns of fitting a bridgeport type mill with a VFD? I suppose that low speed torque would be sacrifised, but how feasable is it? My controll (Anilam crusager G)outputs a analog voltage to controll speed and at present it is hooked up to a motor and "controller" board that changes the handwheel on the head. it is slow to opperate and only acurate/ repeatable to about 30% of the programmed value. The analog signal should be easy to hook up to the VFD though. Thank you Pieter

Pieter,

I see no cons whatsoever. You will lose torque at lower RPMs, (below perhaps 30-40Hz), but you can also run to as much as 200% of base speed. Overall, it will greatly reduce, though not eliminate, belt changes. You'll still need to change belts when going to very high or very low speeds. I have a Teco FM50 (under $200) on my 3HP BP clone, and love it.

Regards,
Ray L.