Something for Stepper Motor/EMC Users to Try

I've been experimenting with different settings in my emc.ini file to try to
improve the performance of my current project machine (as I haven't sold it
yet!) and I've gotten my best results with the following:

[TRAJ]
CYCLE_TIME = 0.05 ;Make this long, hundreds of times [AXIS]CYCLE_TIME

;These are just for your reference.
;After making the other changes,
;see if you can't get better accel and velocity
;than you had previously
DEFAULT_VELOCITY = 1.25
MAX_VELOCITY = 1.25 ;With my INPUT_SCALE=4000 this is 75"/min
DEFAULT_ACCELERATION = 0.9
MAX_ACCELERATION = 0.9

;This is the real trick, do this for every axis
[AXIS_n]
CYCLE_TIME = 0.00018
;Get this number as low as possible,
;and make it the same for every axis. Try to get below .0002.
;I have gone as low as .000177 before the EMC won't run anymore.

You'll probably want to install the latest 12-Nov-1999 release and also the
latest emcmot.c which can be downloaded from:

ftp://ftp.isd.mel.nist.gov/pub/emc/emcsoft/linux_2_0_36/emcmot.c

Put this file on a floppy and then:

# cd /usr/local/nist/emc/src/emcmot
# mount /dev/fd0 /mnt
# cp /mnt/emcmot.c .
# umount /mnt
# make PLAT=rtlinux_09J all

The result of this tinkering is that I have significantly increased my
maximum velocity and acceleration, and my motion is really smooth. Be sure to
back up your working emc.ini in case this doesn't work for you!
I'll make inquiries regarding separate MAX_VELOCITY and MAX_ACCELERATION
settings for each axis, and also about Jon Elson's comments on rotary axis
units.

Keep the faith (if possible),

Matt (who is really starting to loathe stepper motors, but is learning a lot
about them anyway)

P.S. I know I haven't made many contributions to the list lately as earning a
living has been rather more tedious and time consuming than usual. I'm also a
slow typist (this post here took almost an hour), but I'm seriously
considering getting one of those voice recognition programs. If I do, you'll
all be wondering, "when is he going to shut up already..." ;)