Acceleration parameters in INI file

[Fred Proctor <proctor-at-cme.nist.gov>]

EMC folks,

Jon Elson asked:

>
I also broke a timing belt in my Y axis drive a couple days ago, right
in
the middle of milling.  I decided that I was having too much of a jerk
when motion started since I put in the FF1=5.0 parameter, and I'd
better look into it before I broke another belt.  Well, the default
acceleration was 10.0, and that is in/sec squared!  A bit much for a
bridgeport, and the logging charts show it was actually doing it!
I changed it to 2.0 in/sec sq., and things are a lot more gentle, now.
By the way, what is the difference between default acceleration and
maximum acceleration?
<

Yes, reducing the acceleration cuts down on the forces felt when
starting or stopping a move. You can adjust the DEFAULT_ACCELERATION in
the [TRAJ] section of the ini file lower. The units are in user units
(usually inches) per second per second. Lowering this will result in a
more noticeable ramp-up and ramp-down time. This won't negatively affect
the accuracy of moves (it will actually improve it), but it will
increase the time of the move. It also will increase the distance
traveled after you abort a move.

The MAX_ACCELERATION is intended to be the upper limit on acceleration,
for systems that can specify acceleration values on a per-move basis. I
support this in the motion system, but there's no way to access this
from RS-274 so it's not enforced now and can be ignored.

--Fred