Hi All,

I'm learning the gcode which is output from Sheetcam for my plasma cutting table. I have a touch off Z-axis for referencing the torch height to the top of the material before each cut. I'm using the "MP3000-DTHC-SmlArcFix" post processor which is written for Mach.

Here's the first few lines of the gcode:

N0030 G21 (Units: Metric)
N0040 G53 G90 G40
N0050 F1
N0060 (Part: Sheetcam Tryout - Square)
N0070 (Process: Outside Offset, VISIBLE, T1: Plasma, 2 mm kerf)
N0080 M06 T1 F2000 (Plasma, 2 mm kerf)
N0090 G00 Z12.7000
N0100 X857.4000 Y942.6000
N0110 G28.1 Z12.70
N0120 G92 Z0.0
N0130 G00 Z0.1370
N0140 G92 Z0.0
N0150 G00 Z5.0000
N0160 M03

Questions:

Why is F1 (1mm per minute ?) inserted in line N0050. It's correctly set at 2000 mm/min three lines later.

What is the meaning of having a tool change on line N0080. I'm a beginner to this but I can't see any purpose to this, I mean there is no tool change. I would have expected just the feed rate to be set and that's it.

Line N0090 says rapid the Z-axis to 12.7 but at this point the Z-axis position is not known, it hasn't been referenced / homed. With a floating Z-axis on a plasma cutter the homing is the touch-off and is the top of the material, and this is not done until after this starting on line N0110.

I think I've got the rest of the gcode worked out but the above has me stumped at present.

Thanks,

Keith

THE F1 is a safety to protect the operator or machine , in the event of something weird happenning it will be at F1 not F2000.

The M6 tool change is just a hold over. The post was developed from a generic post that included tool changes. Then extra code was not removed from the post.

The Z height should be a SAFE Z position. You may want to check your sheetcam setup to make sure it is correct.  When you started up the machine do you REFHOME the machine so MACH knows where it is on the table?? (;-) IF not then mach does NOT know where it is and that value would be incorrect.

Just a thought, (;-) TP

OK just finished looking at some old SC notes. The tool change was left in as a means of setting different feedrates,etc for different conditions. In most cases a simple plasma Program may not need it BUT it is left in there just in case.

Hope that helps, (;-) TP

Thanks for the info BR549,

I've since found out that after switching on my plasma table each time, I need to do an approximate manual reference of each axis. This is so that when Mach is used to do homing the axis positions are approximately correct and the preset slowdown distance before the homing switches will be accurate enough. Then the true accurate homing will happen when it contacts the homing switches.

Regards,

Keith.