Re: [CAD_CAM_EDM_DRO] EMC step rate configuration

John Murphy wrote:

> I'm finishing up my grizzly/EMC conversion... How cool it feels when
> you
> jog your first axis!
>
> Now I'm thinking I've made a big design mistake: I used some surplus
> motors
> with pretty high resolution encoders, which I'm driving with the
> wonderful gecko G320's, and are coupled to 10 TPI acme screws
> with 2:1 reductions. Working through the math, I end up with
> MANY MANY (Way too many!) steps per inch. Way more than I
> can use... (like 100000+ steps per inch)
>
> Configuring EMC, I'm finding the relationship between MAX_VELOCITY
> and INPUT_SCALE to limit my max speed. I'm using the default
> PERIOD, etc setting in EMC on a K6-266. Obviously, if I set
> the velocity too high, EMC hangs during startup, since I've
> set things faster than the pulses could be output.
>
> Short of changing encoders/motors (which I've done temporarily on
> my Z axis, just to get a tolerable speed for tool changes), what are
> my options? I don't care about speed while I'm machining much (it's
> not a production type machine for obvious reasons), but jogging, etc
> is slow.

Well, this is the problem you run into with a pseudo-servo system!
I have a real servo system, and am running with 20,000 encoder counts
per inch on X and Y, and 40,000 counts/in on Z, and it is no limit at all,
even on a 100 MHz Pentium classic! I have my limits set at 120 IPM,
but that is limited more by my motors and servo amps than EMC.
EMC would have no problem going much faster. It only has to
make a position/velocity update 1000 times a second.

Jon