Backplot issues

[Chris Stratton <stratton-at-mdc.net>]

I was using tkbackplot to preview a 2 axis milling toolpath yesterday,
and getting some frustrating results.

The main problem seems to be that my stepper setup slows down the
computer a lot, and so the tkemc display updates infrequently.  It
seems that backplot perhaps connects the points at which the
coordinate display updated or something, because I get horribly
rounded and distorted corners in the backplot window, while the actual
machine makes quite nice corners.  I tried increasing the acceleration
to insane values (20) since the stepper system moves slowly enough
that it isn't needed, but it really seems the problem is with the
display, not with the trajectory planner.

The problem gets worse if I am trying to preview with the stepper
drive turned off and the feedrate override cranked up.

So my questions:

1) is there any easy fix to the distorted corners on the display?

2) is there any way to use tkbackplot to rapidly but accurately
preview the toolpath?  I'm thinking of some way of running it offline,
as opposed to simply disabling the drives and cranking the feedrate,
which wouldn't work on a closed loop machine anyway.

Chris

-- 
Christopher C. Stratton, stratton-at-mdc.net
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
http://www.mdc.net/~stratton
NEW PHONE NUMBER: (617) 628-1062 home, 253-2606 MIT