Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: KTM on February 15, 2012, 11:08:57 AM

Title: Trajectory planning and CV
Post by: KTM on February 15, 2012, 11:08:57 AM
Hi all,

I have retrofitted a CNC plasma table for cutting of thin ducting profiles (0.6 - 1.6mm), so the cutting feed rates are quite fast (8000 -12000mm/min). The problem that I am having is that I cant seem to get the CV settings right with the post from the Map ducting software.
Attached is an example of the code.

The only way that I can get the machine to run borderline acceptable is to tune the motor velocity right down to 200mm/min, and set the CV distance to 3, but this is very slow and worse than the old analog control that I replaced.   :(

I have tried to:
1) set the look ahead higher - no change
2) tick "stop CV on angles > 89 (or 79 or 44) - the corners are better,the long arcs are smoother, but the tight curves are segments of small line, so they run with a jerky motion.( in the Map software, there is a "simplify islands" check box that removes a lot of this, but not everything.)
3) tick "Plasma mode" - no change
4) I have tried making the "look ahead" larger or smaller - no change

I have been trying to solve this problem since December, so Please, if someone has suggestions - let me know, your help will really be appreciated.


Title: Re: Trajectory planning and CV
Post by: Karl W on February 15, 2012, 09:28:07 PM
I have similar problems, but in 3D.

I think you may wish to try Tempest. I have been trying it out. It is pretty slow in 3D but from what I hear should do well on a plasma table. It isn't supported so I have no idea how it would handle your torch height etc. Whatever is in the last beta is what you get. No feedrate override. Sort of crude but might be an improvement over regular mach for your purposes. You can download a copy from the Tempest thread on the Mach 3 forum. Sept 29 is the most recent one. Look for attachments on posts from Art.
Title: Re: Trajectory planning and CV
Post by: KTM on February 16, 2012, 07:55:08 AM
I spent the day testing Tempest, and it seems that my USB board (Xulifeng) is not supported.
If I run the code in Tempest on my computer, I can see the feedrate changing for circles and curves, but when I run it on the machine, it does not change, and the results are the same :(.

Any other ideas?
Title: Re: Trajectory planning and CV
Post by: Hood on February 16, 2012, 02:36:26 PM
Good chance it is your USB controller that is the problem. Test with the parallel port if you can.
Title: Re: Trajectory planning and CV
Post by: KTM on February 17, 2012, 12:53:46 AM
I only realized later that there is a menu item under the config menu to enable Tempest  :-[ .

It runs the code much better, but.... I cannot save the settings, and on the machine I hide the menu.

So... now I tried using VB script, but it will not select the Planner menu item. ???
Is there anyone that can modify the Mach code to save the Planner settings and enable the checkbox - or can it be added to the XML?