Re: Backplot issues

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

Chris Stratton wrote:

> 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
> 
> 


Just incase you want to try it, emcplot3d will plot a program without 
running the rest of emc.

To build it you will need either OpenGL or Mesa (which is a free 
"OpenGL" workalike). You might already have it.

cd emc/src/emcplot3d

make USE_NEW_INTERPRETER=1 PLAT=<plat>

where <plat> is linux_2_2_14, or linux_2_4_1, etc.


then from the top-level directory



plat/<plat>/bin/emcplot3d --prog <programfile> --scale <scalefactor>

ie

plat/linux_2_2_14/bin/emcplot3d --prog programs/cds.ngc --scale 0.05

Slide the part with the arrow keys. shift + arrow keys to rotate.
<space> key  return to original view. <ESC> key to quit.

The red, blue and green lines are just to show the direction of x,z and y.


Sometimes the program pauses just before it should have brought up the
display. Ussually I can tap an arrow key a couple of times to wake it up.



-- Will







-- 
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William Penn Shackleford III			shackle-at-nist.gov
National Institute of Standards & Technology	Tel:	(301) 975-4286
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