Messages

1

General Mach Discussion / Re: Different speeds on lines and arcs

« on: October 08, 2009, 01:33:18 PM »

Ok,
thanks for your replies. Update solved the problem. Thanks for guidance

2

General Mach Discussion / Re: Different speeds on lines and arcs

« on: October 01, 2009, 05:22:46 PM »

Thanks for the support Hood. I greatly appreciate it

3

General Mach Discussion / Re: Different speeds on lines and arcs

« on: October 01, 2009, 09:57:56 AM »

I can't tell you how the machine is set up because i am just the programmer of the application which converts plt files into gcode.A axis rotates the knife. I run demo version of mach3 and got xml from machine manufacturer. however, even on my pc which is not connected to anything i see that speed varies( label units/min. ). Meybe it is because of the changing direction of the movement? even if i round the corner and movement should be smooth, i observe dramaticac speed changes.

edit:
i think the reason why A axis is not associated with pins is that my pc is not connected and xml is from my pc, not the one from the plotter.

4

General Mach Discussion / Re: Different speeds on lines and arcs

« on: October 01, 2009, 09:12:54 AM »

thanks for the effort, really
BTW, Could you tell me what mach does when generating toolpath? Because CPU load is the same as when Mach does nothing. Effect is that i wait for ages when i load file with many arcs.

5

General Mach Discussion / Re: Different speeds on lines and arcs

« on: October 01, 2009, 07:23:51 AM »

I use g64 ( it appears in the line with other codes in the line MILL->G15 G3 (...) G64).
i unfortunately must compose my arc from ie 10 arcs because i import PLT file and if there is big arc in the file it is made of straight lines (ie half circle is made from 20 lines) so in order to avoid stopping machine and turning knife in the air, i round corners between these short lines, so that i do not need to stop the machine and the resulting path is smoother.
Part of my file:
g90
g64
G01 X1775.295 Y-15.820
g17 G02 X3.923 Y-0.757 I-5.576 J-39.439 G91 A -5.749
G90
G01 X1782.358 Y-17.348
g17 G02 X3.835 Y-1.122 I-10.880 J-44.309 G91 A -5.020
G90
G01 X1789.157 Y-19.480
g17 G02 X3.716 Y-1.468 I-13.443 J-39.453 G91 A -5.494
G90
G01 X1795.702 Y-22.227
g17 G02 X3.562 Y-1.810 I-17.932 J-39.696 G91 A -5.258
G90
G01 X1801.910 Y-25.538
g17 G02 X3.384 Y-2.126 I-21.989 J-38.757 G91 A -5.140


when i type one big arc, the speed is constant for this arc, it is not a problem when speed differs for a line which is long ( either straight or in arc) but i only can generate little, short arcs and between these arcs speed differs most and couse machine jerking

thanks for your support

6

General Mach Discussion / Re: Different speeds on lines and arcs

« on: October 01, 2009, 07:01:30 AM »

Thanks for replies,
The problem is i test it on my pc, unplugged from machine, and i observe "deviations" ,what i observe is also reported by the owners of the machine, so it;s not machine issue. I suspect it is something with mach configuration or mach algorithm for generating motor steps. My gcode is composed virtually  only of arcs, but they are very short (i take curve made of straight lines and then round the corners). gcode is correct. We tried to "walk around" the problem setting different speeds for arcs and straight lines (which are rare, but then they are very long so machine jerking is not a problem, speed is constant on a line). It helped a little for diminishing differences between speed for line and speed for arc, but when my path is composed of only arcs ( ie 10 arcs one after another making halfcircle) the speed differs while cutting such a path. ( i hope you follow me )

7

General Mach Discussion / Different speeds on lines and arcs

« on: October 01, 2009, 05:22:45 AM »

Hi,
i have a problem. Mach does not maintain constant speed (feedrate)  when executing my gcode. Differences are rather significant, ranging from 1800 to 1400 mm/min (you may imagine the jerking). and appear when i cut corners using g02/g03. my machine is plotter for cutting glass (thus high speed) but i observe this on 3 different pc, including C2Quad 2,4Ghz.
Has any of you came across similar phenomenon?