help with nesting/stepping.

[drummerboy]

hi,

can anyone help with some nesting/stepping issues. I use a Fagor router, and produce flat peices (up to 200 per sheet), sheets between 2/20mm thick, using cutters, drill bits, chamfer bits etc.

is there an industry standard for stepping? for example. at a previous place I worked, in Excellon, it would be program co-ordinates, followed by the co-ordinates each step would be at.

m01xy
m01xy
m01xy
m98xy (step1)
m98xy (step2) etc etc

which was nice and easy, and if you broke a bit, you could plonk it back on whichever was the last step and let it go to there.

In my new place, no one has really looked at post processing, and the machine works with the standard output. we use Alphacam and it out puts incredibly complex stepping subroutines first, and then the co-ordinates, although it's a bit backwards, as the programs themselves are the subroutines. here is an example. the zero point at the machine is top right, then the g-codes off set t1 by -1000, (which also appears to be machine offset), t2 -1140, t3 -1300 and t4 -1440, so xy0 is at the bottom left in theory.

N10 G71
N20 G20 N1
N30 P1 = K -1000 P2 = K -877
N40 G20 N54
N50 G43 T4.4
N60 G0 Z30
N70 M72
N80 G4 K1
N90 M56
N100 G57
N110 G0 X28.245 Y314.425
N120 G20 N10
N130 G0 X28.315 Y661.695
N140 P1 = K -999.93 P2 = K -529.73
N150 G20 N54
N160 G57
N170 G20 N10
N180 P1 = K -1000 P2 = K -877
N190 G20 N54
N200 G57
N210 G0 X134.715 Y314.425
N220 P1 = K -893.53 P2 = K -877
N230 G20 N54
N240 G57
N250 G20 N10
N260 P1 = K -1000 P2 = K -877
N270 G20 N54
N280 G57
N290 G0 X134.785 Y661.625
N300 P1 = K -893.46 P2 = K -529.8
N310 G20 N54
N320 G57
N330 G20 N10
N340 P1 = K -1000 P2 = K -877
N350 G20 N54
N360 G57
N370 G0 X241.185 Y314.425
N380 P1 = K -787.06 P2 = K -877
N390 G20 N54
N400 G57

then carries on, and same for T3.3 until the end of the program, which is.

N3200 P1 = K -41.7 P2 = K -529.8
N3210 G20 N54
N3220 G56
N3230 G20 N11
N3240 P1 = K -1000 P2 = K -877
N3250 G20 N54
N3260 G56
N3270 M55
N3280 M34
N3290 G0 G44 Z0
N3300 G20 N1
N3310 M30
N3320 G22 N10
N3330 G99 Z18
N3340 G81 X28.445 Y314.625 Z18 I0 F353
N3350 X78.445 Y314.625
N3360 X78.445 Y34.775
N3370 X28.445 Y34.775
N3380 G80
N3390 G24
N3400 G22 N11
N3410 G0 Z3
N3420 G1 G41 X0.07 Y347.5 Z -8.4 F0528
N3430 X106.32 F3600
N3440 Y1.4
N3450 X0.17
N3460 Y347.6
N3470 G40 Y347.896
N3480 G0 Z10
N3490 G24

.... which to me is backwards, and I don't seem to be able to select a piece to jump to if a tool breaks.

I have been looking in to G25's, haven't been able to understand yet G26/27/28. What about using G90, G91's with subroutine programs? G31? aarrgh. Anyways, suggestions helpful. cheers.