lead in inside offset

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jaker2
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lead in inside offset

Post by jaker2 »

Strange thing happens when i go to cut a file for a second time immediately after a successful cut. First cut works great then on the second attempt the initial/first pierce and lead in go to outside instead of inside. once first cut is done then it all reverts back to inside pierce and lead in as per settings.

Using mach3 and sheetcam. Any ideas? Thanks!
robertspark
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Re: lead in inside offset

Post by robertspark »

gcode is gcode.... it don't change.....

what are your starting coordinates in both instances.....
are you resetting the work coordinates before both cuts the same and starting from the same position

it sounds like your first cut is starting from the centre of the circle and the second has a starting point outside that circle (for some reason)

all coordinates in gcode are the finishing point
jaker2
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Re: lead in inside offset

Post by jaker2 »

Hi Robert, yes same gcode and I am resetting all coordinates before both cuts. It's happened on different files as well. It's weird.
robertspark
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Re: lead in inside offset

Post by robertspark »

can you post the first part of your gcode? just enough to see the circle cut sort of thing.

that is odd if everything is the same at both starts
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Larry83301
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Re: lead in inside offset

Post by Larry83301 »

robertspark wrote: Fri Jul 05, 2019 5:17 pm can you post the first part of your gcode? just enough to see the circle cut sort of thing.

that is odd if everything is the same at both starts
Also the end portion of the file, it may NOT be turning of the G2 or G3 code properly.


Larry
robertspark
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Re: lead in inside offset

Post by robertspark »

Larry83301 wrote: Fri Jul 05, 2019 5:23 pm
robertspark wrote: Fri Jul 05, 2019 5:17 pm can you post the first part of your gcode? just enough to see the circle cut sort of thing.

that is odd if everything is the same at both starts
Also the end portion of the file, it may NOT be turning of the G2 or G3 code properly.


Larry

good point
jaker2
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Re: lead in inside offset

Post by jaker2 »

Thanks guys!

First section:
N0010 (Filename: spartan wing detail 10 120ipm vert.tap)
N0020 (Post processor: MP1000-THC bjnt.scpost)
N0030 (Date: 04/07/2019)
N0040 G20 (Units: Inches)
N0050 G53 G90 G40
N0060 F1
N0070 (Part: spartan wing detail)
N0080 (Operation: Set variable switchOffset = 0.23 )
N0090 (Operation: Outside Offset, 0, T2: Plasma, 0.025 in kerf)
N0100 M06 T2 F120 (Plasma, 0.025 in kerf)
N0110 G00 Z1.5000
N0120 X0.9485 Y3.6009
N0130 Z0.1500
N0140 G28.1 Z0.12
N0150 G92 Z0.0
N0160 G00 Z0.2300
N0170 G92 Z0.0
N0180 G00 Z0.1500
N0190 M03
N0200 G04 P0.02
N0210 G01 Z0.0000 F65.0
N0220 G02 X0.9307 Y3.7628 I0.0721 J0.0899 F120.0
N0230 G01 X0.9841 Y3.7797
N0240 X0.9865 Y3.7807
N0250 X1.0413 Y3.8112
N0260 X0.7703 Y0.9380
N0270 X0.7551 Y0.8876
N0280 X0.7197 Y0.8298
N0290 X0.6692 Y0.7853
N0300 X0.6247 Y0.7625
N0310 X0.9069 Y3.7563
N0320 X0.9121 Y3.7571
N0330 X0.9139 Y3.7575
N0340 X0.9307 Y3.7628
N0350 G02 X0.9797 Y3.6075 I-0.0532 J-0.1022
N0360 M05
N0370 G00 Z1.5000
N0380 X2.6357 Y10.5320
N0390 Z0.1500
N0400 G28.1 Z0.12
N0410 G92 Z0.0
N0420 G00 Z0.2300
N0430 G92 Z0.0
N0440 G00 Z0.1500
N0450 M03
N0460 G04 P0.02
N0470 G01 Z0.0000 F65.0
N0480 X2.6690 Y10.5978 F120.0
N0490 X2.6704 Y10.5937
N0500 X2.6751 Y10.5522
N0510 X2.6694 Y10.4638
N0520 X2.6660 Y10.4444
N0530 X2.6329 Y10.3292
N0540 X2.6235 Y10.3049
N0550 X2.5946 Y10.2406
N0560 X2.5811 Y10.2160
N0570 X2.6195 Y10.6233
N0580 X2.6536 Y10.6449
N0590 X2.6690 Y10.5978

End Section:
N11370 G03 X3.9816 Y9.8269 I-0.7403 J-0.0938
N11380 G01 X3.9775 Y9.8361
N11390 X3.9770 Y9.8373
N11400 X3.9301 Y9.9197
N11410 X3.9293 Y9.9209
N11420 X3.9199 Y9.9337
N11430 X3.9190 Y9.9348
N11440 X3.8765 Y9.9809
N11450 X3.8831 Y9.9927
N11460 X3.8835 Y9.9936
N11470 X3.9269 Y10.0871
N11480 X3.9275 Y10.0886
N11490 X3.9549 Y10.1747
N11500 X3.9552 Y10.1762
N11510 X3.9596 Y10.1993
N11520 X3.9598 Y10.2006
N11530 X3.9659 Y10.2733
N11540 X3.9660 Y10.2743
N11550 X3.9662 Y10.2917
N11560 X3.9660 Y10.2939
N11570 X3.9538 Y10.3693
N11580 X3.9527 Y10.3728
N11590 X3.9230 Y10.4332
N11600 X3.9212 Y10.4358
N11610 X3.9047 Y10.4550
N11620 X3.9030 Y10.4566
N11630 X3.8740 Y10.4799
N11640 X3.8719 Y10.4813
N11650 X3.8311 Y10.5021
N11660 X3.8290 Y10.5030
N11670 X3.7884 Y10.5151
N11680 X3.7868 Y10.5154
N11690 X3.7444 Y10.5224
N11700 X3.7433 Y10.5226
N11710 X3.6850 Y10.5270
N11720 X3.5409 Y10.5349
N11730 X3.5405
N11740 X3.4586 Y10.5366
N11750 X3.4582
N11760 X3.4090 Y10.5360
N11770 X3.4038 Y10.5347
N11780 X3.3738 Y10.5391
N11790 X3.3790 Y10.5886
N11800 Y10.5911
N11810 X3.3747 Y10.6387
N11820 X3.3739 Y10.6420
N11830 X3.3564 Y10.6879
N11840 X3.3544 Y10.6912
N11850 X3.3296 Y10.7222
N11860 X3.3276 Y10.7242
N11870 X3.3093 Y10.7388
N11880 X3.3078 Y10.7398
N11890 X3.2868 Y10.7520
N11900 X3.2836 Y10.7533
N11910 X3.2336 Y10.7660
N11920 X3.2299 Y10.7664
N11930 X3.1666 Y10.7634
N11940 X3.1637 Y10.7629
N11950 X3.1066 Y10.7464
N11960 X3.1051 Y10.7459
N11970 X3.0589 Y10.7262
N11980 X3.0126 Y10.7054
N11990 X2.9404 Y10.6775
N12000 X2.8629 Y10.6573
N12010 X2.8430 Y10.6546
N12020 X2.8161 Y10.6520
N12030 G02 X2.8003 Y10.8141 I0.0732 J0.0890
N12040 M05
N12050 G00 Z1.5000
N12060 X0.0000 Y0.0000
N12070 M05 M30
robertspark
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Re: lead in inside offset

Post by robertspark »

I cant see anything wrong with the radius' / arc motion.... it calls G02 when needed.

I can however see other things that I'd personally not be happy about....

Take these as just viewpoints of one person...... if what you have works well for you ignore them....

Firstly I presume you are using Mach3..... please advise if this is not the case as it may change things

Lets work through this slowly, hopefully it will make sense what I'm explaining line by line:

Code: Select all

N0100 M06 T2 F120 (Plasma, 0.025 in kerf)
no problem - sets current feedrate (until over-ridden)

Code: Select all

N0110 G00 Z1.5000
no-problem - rapid retract Z to 1.5" above Z0

Code: Select all

N0120 X0.9485 Y3.6009
no problem - rapid move to start point X&Y

Code: Select all

N0130 Z0.1500
problem in my opinion ---- drop torch down to 0.15" above Z0..... are you sure.... that is a bit low from my experiance of plasma and allowance for crud on my slats + material warpage.

Code: Select all

N0140 G28.1 Z0.12
problem in my opinion ----- you are telling the machine to home the Z axis towards the home position at the CURRENT FEEDRATE (set at N0100 above), at MACHINE CO-ORDINATE POSITION Z0.12" it will change to the reference axis velocity as set in the configuration.
https://machmotion.com/cnc-info/g-code. ... rence_Axis
Wow.... probing at 120 in/min... bearing in mind that you are using G92 to set a temporary offset for the top of the material....

Code: Select all

N0150 G92 Z0.0
N0160 G00 Z0.2300
N0170 G92 Z0.0
not really a problem.... but a code optimisation of the post processor in my opinion
Consider the 3 lines..... once the torch homes the Z axis you are asking it to set a temporary offset (G92), then asking it to RAPID rise to 0.23" above the Top of Material and then reset the Z axis via temp offset G92 to Z0......
Why??
If your post processor is written to set the switch offset as

Code: Select all

N0150 G92 Z-0.023 (minus!)
All you have to do is one move to rapid up to the pierce height.... no stopping in between to set things again and then rapid up to pierce height.... given your swich offset is set to below the top of material which is correct.

Code: Select all

N0180 G00 Z0.1500
No problem --- Rapid up to pierce height

Code: Select all

N0190 M03
No problem - fire the torch

Code: Select all

N0200 G04 P0.02
No problem - wait for pierce

Code: Select all

N0210 G01 Z0.0000 F65.0
Problem!!! ---- you are telling the machine to move (controlled feedrate) down to the Top of the Material...... why??? You should be dropping to the CUT Height.... not dragging the torch across the top of the material {{{ unless you are using a drag shield.... but this is a THC post processor..Post processor: MP1000-THC bjnt.scpost.}}}

Code: Select all

N0220 G02 X0.9307 Y3.7628 I0.0721 J0.0899 F120.0
Maybe a problem --- your lead in arc (G02) is a clockwise arc..... and you are cutting an internal hole in a clockwise direction.....
The advice tends to be an internal hole should be cut in a counterclockwise direction (but it may depend on your plasma cutter) as it should give you a squarer finish because of the swirl of the plasma gas (true on my cutter anyway) ... see page 3/6 of the linked PDF
https://www.google.com/url?sa=t&rct=j&q ... NyPrgXm0HC

YMMV, again just comments / advice to consider.... if its working fine for you then ignore as I don't know your machine setup but you do.
jaker2
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Re: lead in inside offset

Post by jaker2 »

Great stuff Robert, thanks so much for taking the time to point these out (great with design...not so much with gcode). I am using mach3 so will have a look at these.Thanks again!
Brad
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