Re: EMC Real world

[Will Shackleford <shackle-at-cme.nist.gov>]

Ethan Vos wrote:
> OK, I have everything set up to do what I want, now I need to connect to my 
> machine.
> 
> How do I change the parallel port pin-out for XZA instead of XYZ? The .ini 
> file is set up for 4 axis so the A will work properly. I know I'll probably 
> need to add a parallel port.
> 
> And I noticed something odd. The A axis move very slowly when a G00 is 
> commanded, but will move very quickly if the G00 is combined with either 
> the X or Z axis.
> 
> In terms of stepper drives, am I better to use the existing Compumotor Zeta 
> drives or change to something like the Gecko? I need the stepper to receive 
> 5,000 steps/rev and 5 rev/inch so 25,000 steps/inch. My target is 10 inches 
> per second so I need 250,000 steps/sec.
> 
> Thanks.
> 
> Ethan
> 
> 
> 
> 

For G1,G2, and G3: RS274 seems to require that things work like this.
If there is an AB or C motion and no XY or Z motion and one isn't in 
inverse time mode the feedrate is in
degrees per minute otherwise it is in inches/mm  per minute and the 
speed of the rotational axis is computed so they will complete in the 
same time interval as the linear motion. So if you have  a small linear 
motion combined with a big rotational one they both have to complete in 
the same time and the rotational motion may be very very fast.

For G0 it looks like we are just doing the samething we need to do for 
G1 except substituting the traverse rate for the feedrate. We could I 
suppose make G0 allow the linear and rotational moves take different 
periods of time. I am not sure whether this would be better or if it is 
worth the effort to change.


-- Will