Re: [CAD_CAM_EDM_DRO] Thoughts on PC Based Control Retrofit....pictures of the specimen

Tim Goldstein wrote:

> No, the motors do not have any encoders they run open loop. The reason for 6
> wires is that they were run as unipolar. They will run just fine as bipolar
> 1/2 coil and you will get better performance. The motors are most likely 8
> wire motors so you have a lot of flexibility in how you drive them. Matt
> used some fairly expensive high voltage drives on his conversion. I have
> tested my series II (like a series I on steroids) with a Camtronics bipolar
> chopper driver at 24 V and was getting about 30 ipm on the X and Y and 15
> ipm on the Z. I just ordered a single Gecko G210 with the NEMA 42
> modification to try and see how that works. Talking to Mariss (owner,
> designer, promoter, and I imagine janitor) at Gecko he tells me that all
> else being the same max RPM on a stepper will increase in direct proportion
> to the drive voltage. The G210's are good up to 80 volts. So, if it works as
> planned I should be able to get 40 - 45 ipm on the Z and 80 - 90 ipm on the
> X & Y. Testing will be reported to the group.

My mistake was to use the whole coils rather than half. Still with
72V/10A drives I got 54ipm on X,Y, and Z. Unfortunately (actually it IS
fortunate), the machine is gone, the new owner is happy, and sleeping
dogs will be left to lay where they are...

What is the "NEMA 42 modification" ?

I spoke with Marty on the phone this evening and I think he could also
use some recommendations on how to build an inexpensive 80V supply if he
goes with Gecko drives.

Matt