[ladzhari]

I'm gathering the parts to retrofit a cheapo 3-in-1 lathe/mill to CNC. I've got funny Servodisc geared PM DC motors (type 9FGHD) with HP HEDS type quadrature encoders for X and Y and am trying to figure out what drive to use for them. These motors apparently have very low inductance and require drives capable of handling this (high switch frequency, added low-pass filtering, or linear mode).
The spindle drive I'm hoping to use is a 100V DC 8A treadmill motor with a 4000-count BEI quadrature encoder.

Would the Viper 100 be appropriate for the X and Y? I tried downloading the manual to see the specs here:
http://www.larkencnc.com/dloads/viper-manual.pdf

but the manual seems to be corrupt or damaged, Foxit or Adobe Reader won't open it.

I guess the spindle motor drive won't matter too much as long as the encoder resolution isn't too high, 4000 count @ 1000 RPM = 66Khz. I have other encoders laying around though with lower counts.

[ladzhari]

A nice member emailed me the doc (v2.0.1), in case anyone else wants to read it, I put it here:
http://project1.org/larkendrives.pdf

It seems to have more up-to-date information than the Web site.

[Larken]

Can you post a picture of that pancake motor ? Any voltage or current specs ?

Larry

[ladzhari]

The specs say 14.6V @ 6.2A. Pretty low number of watts, but they're geared so (hopefully!) have enough torque. Unfortunately the inductance is not listed.

The reason I like the viper setup is so the controls are movable to another system easily. This first lathe CNC conversion setup is just kind of a learning exercise.

[Larken]

Thats a very low voltage. I don't recommend running the Vipers under 24 volts, or the mosfets can starve.
Maybe a LC filter before the motor.
What do you think ?? (calling AL the Man)

[Al_The_Man]

Some of the qualities of disc motors make them very attractive, high acceleration etc, but I feel the limiting factor here is going to be the voltage, as Larry said.
Al.

[ladzhari]

Got it, thanks a lot for the response guys!

These geared servodisc motors have a great form factor, hopefully they work OK -- if a bit on the slow side. But they are very quiet for a geared setup.

I'll make an attempt to use YAPSC:10V project with a small linear servo amp. I think everything I need to build those is in my junk box, and PICs are easy to understand