I finally did it.. I installed mach3 on an xp machine and setup a machine. I setup linuxcnc and mach with all 3 axis set to 500ipm and 30 in/sec/sec.
First I ran the tort.ngc in both systems. (this is a torture test program that was used to make sure linuxcnc planner was behaving) Mach3 and linuxcnc ran this program pretty close to the same time. A bit over 1 minute (mach was a few seconds faster). (this is running strait G64 for all tests as I don't see a way to set a tolerance in mach - I may have missed it) This program has rather large arcs and line segments. http://git.linuxcnc.org/gitweb?p=linuxcnc.git;a=blob;f=nc_files/tort.ngc;h=9775cf057c99d18801e1a2dc49c3561683bd11a9;hb=HEAD Next. The demo version of mach only allows 500 lines. So it took a bit to figure out what to run - Jeff E said a section of spiral.ngc would be a good test. I found an older version that didn't use looping and cut it to under 500 lines. (this has short line segments making a spiral. http://pastebin.ca/2449681 The spiral starts out at about a 2 inch radius. -Mach starts out running the program at about 450ipm. The whole program takes about 12 seconds. -Linuxcnc starts out running about 110ipm. The whole program takes about 50 seconds. Interesting..... I was expecting it to be slower but this was a little surprising... I tried G64P.010 and it peaks at 150ipm starting. P.050 gets you 200ipm. Not knowing exactly how all the internals work - I was thinking that something was wrong with the setup of one or the other.. So I created a circle with a 2 inch radius. I ran it in linuxcnc and it peaks at about 464ipm. So that matches what mach was doing with the line segments. Looking through mach - you can setup lookahead. I set lookahead to 2 - what linuxcnc currently can do. The above spiral program peaked at 110ipm and took about 54 seconds to run. Well there you go.. It seems to be with strait G64 - linuxcnc 1 segment lookahead seems to be the limiting factor. There is some situations that the G64 Px.xxx will improve the path speed. (longer line segment means higher peak velocities.) This also suprised me - both mach and linuxcnc must be using very similar trajectory planning maths. High speed machining/routing/whatever with short line/arc segments is only possible at the moment with linuxcnc on high acceleration machines. (I had to set the acceleration to over 450in/sec/sec to get the velocitys up to 400ipm) In my opinion - this should be a priority. (and I know it is probably going to be a lot of work) (and about all I can do is test) Again - for normal machining I think the trajectory planner is more than adequate and way better than it was. (I don't need this currently as all my machining is done sub 50ipm and normally doesn't have short line/arc paths :) ) Discuss... (of course I could be missing something obvious) (A work around perhaps?) sam ------------------------------------------------------------------------------ How ServiceNow helps IT people transform IT departments: 1. Consolidate legacy IT systems to a single system of record for IT 2. Standardize and globalize service processes across IT 3. Implement zero-touch automation to replace manual, redundant tasks http://pubads.g.doubleclick.net/gampad/clk?id=51271111&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
