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Author Topic: Plasma Relay switch off before cut is complete  (Read 245 times)

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Plasma Relay switch off before cut is complete
« on: December 03, 2020, 05:42:09 AM »
Hi Gentlemen,

I apologize in advance if this is a dumb question, but it has me scratching my head.

I am very new to Mach3 and to CNC in general, i have built a plasma system and have started running test cuts but now i have run into a problem i have no idea to solve and i cannot seem to find any solution online. not for a lack of searching, might be for a lack of understanding.

I run a Digital Dream UC300 usb controller on Mach3 (Licensed), and i use Sheetcam (Unlicensed) still just doing simple test cuts.
I have a floating head setup.

My machine runs the sequence correctly as far as i can gather, it probes down finds 0, goes up, starts the plasma cutter, lowers down,
start the cut and all looks great, but at the end of each part cut the plasma cutter relay switches off before the part cut is complete.
This happen on long cuts and short cuts, it seams as if it only cuts a certain % of the cut.

What it appears to me is the M05 is executed before the cut is complete.
if i run it in Sheetcam simulator the Torch switches off in the correct place, but the moment i run it on mach it constantly switches off before it has completed the cut path.

Some thing like this.
 _ _ _
| _ _ _|

It appears to me the M05 is triggered in the loading part of the script where it reads 20 lines ahead.
I have checked "Ignore M calls while loading" decreased the read ahead number.

To confirm it is not earthing or some other factor i have removed the M05 from the Gcode and let the torch run the sequence, once i do this
the torch stays on and would run the cut without the switching off, in my mind eliminating external issues that might cause the issues, i have also tested this without powering the Plasma cutter on a dry run, the same occurs and on more or less the same place in the code.

I have disabled all lead-in/lead-out, tried various options on the lead-in's/out's.
I have increased Pierce delay to 1.1 to try and see if the G4 would help.

but in the G-Code the M05 is called before the G4, see bellow, so it goes from coordinates to M05, but it appears M05 executes
before the coordinates portion has finished.

So somewhere i am not understanding something.

I truly hope there is someone out there who can shine a light on this for me, thank you in advance.

Here is a sample of a test G-Code.
N0010 (Filename: Test.tap)
N0020 (Post processor: Mach3 plasma THC with scriber and backlash compensation.scpost)
N0030 (Date: 03/12/2020)
N0040 G21 (Units: Metric)
N0050 F1
N0060 G53 G90 G40
N0070 (Part: Test)
N0080 (Operation: Outside Offset, Layer 1, T1: Plasma, 1.5 mm kerf)
N0090 G00 X89.3579 Y45.3663
N0100 G28.1 Z10.00 F500.0
N0110 G92 Z0.0
N0120 G00 Z2.5000
N0130 G92 Z0.0
N0140 G00 Z1.0000
N0150 M03
N0160 G04 P1.1
N0170 G01 Z0.4000 F100.0
N0180 X89.8049 Y38.9692 F1000.0
N0190 X91.2500 Y32.7215
N0200 X93.6574 Y26.7779
N0210 X96.9674 Y21.2855
N0220 X101.0980 Y16.3803
N0230 X105.9470 Y12.1839
N0240 X111.3942 Y8.8002
N0250 X117.3049 Y6.3129
N0260 X123.5325 Y4.7837
N0270 X129.9230 Y4.2504
N0280 X136.3180 Y4.7262
N0290 X142.5592 Y6.1994
N0300 X148.4920 Y8.6334
N0310 X153.9695 Y11.9680
N0320 X158.8560 Y16.1207
N0330 X163.0306 Y20.9885
N0340 X166.3898 Y26.4509
N0350 X168.8505 Y32.3727
N0360 X170.3517 Y38.6072
N0370 X170.8563 Y45.0000
N0380 X170.4175 Y50.9635
N0390 X169.1108 Y56.7985
N0400 X166.9643 Y62.3795
N0410 X164.0241 Y67.5863
N0420 X160.3536 Y72.3068
N0430 X156.0319 Y76.4393
N0440 X151.1519 Y79.8948
N0450 X145.8187 Y82.5990
N0460 X140.1472 Y84.4936
N0470 X134.2595 Y85.5379
N0480 X128.2824 Y85.7093
N0490 X122.3446 Y85.0041
N0500 X116.5739 Y83.4375
N0510 X111.0945 Y81.0434
N0520 X106.0245 Y77.8731
N0530 X101.4731 Y73.9950
N0540 X97.5381 Y69.4926
N0550 X94.3044 Y64.4629
N0560 X91.8417 Y59.0140
N0570 X90.2028 Y53.2634
N0580 X89.4231 Y47.3349
N0590 X89.5194 Y41.3561
N0600 X90.4897 Y35.4558
N0610 M05
N0620 G04 P0.8
N0630 G00 Z10.0000
N0640 X5.0000 Y85.7500
N0650 Z1.0000
N0660 G28.1 Z10.00 F500.0
N0670 G92 Z0.0
N0680 G00 Z2.5000
N0690 G92 Z0.0
N0700 G00 Z1.0000
N0710 M03
N0720 G04 P1.1
N0730 G01 Z0.4000 F100.0
N0740 X4.2500 Y85.0000 F1000.0
N0750 Y5.0000
N0760 X5.0000 Y4.2500
N0770 X85.0000
N0780 X85.7500 Y5.0000
N0790 Y85.0000
N0800 X85.0000 Y85.7500
N0810 X5.0000
N0820 X4.2500 Y85.0000
N0830 Y76.1781
N0840 M05
N0850 G04 P0.8
N0860 G00 Z10.0000
N0870 X0.0000 Y0.0000
N0880 M05 M30

Offline BR549

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Re: Plasma Relay switch off before cut is complete
« Reply #1 on: December 03, 2020, 08:29:17 AM »
Try splitting the M5M30 into 2 lines

Re: Plasma Relay switch off before cut is complete
« Reply #2 on: December 03, 2020, 08:34:11 AM »

Hi BR549,

on the lines N0610 the M05 is on its own, and there it also does this behavior,
in the same code first a circle and then a square, it repeats this behavior twice.

N0600 X90.4897 Y35.4558
N0610 M05
N0620 G04 P0.8

Re: Plasma Relay switch off before cut is complete
« Reply #3 on: December 03, 2020, 08:46:53 AM »
I have a question on how the modern controllers work, when Mach3 post instructions to the UC300 are they passed one by one or in bulk or batches.

If the instructions are sent one by one i assume the issue would be in Mach3, if it is sent in batches could it be that the controller is prioritizing the M05 (set Output) as it enters the controller, which i doubt because the M05 is a set Output command which needs to be set.. i do not know hahaha

So in my little brain i see the Output is set before the instructions is completed, and if that is the case the "Ignore M calls while loading"  is not working as i expected, that it is processing the M code while the move instructions are still working and then pushes the set output in the middle there..

this is just me brain storming, apologies if i am missing the point.

Offline ZASto

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Re: Plasma Relay switch off before cut is complete
« Reply #4 on: December 03, 2020, 03:48:45 PM »
Mach3 is not sending G-code to UC300. It is sending PVT data (Position Velocity over Time).
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Re: Plasma Relay switch off before cut is complete
« Reply #5 on: December 04, 2020, 03:48:34 AM »
On a suggestion on CNC Zone i have added a G04 P1 before my M05 command which seems to work on the test cuts,
i understand it delays the M05 command and by testing it looks like it is doing the trick or at least on these cuts.

I have edited my Post Processor in Sheetcam to add the G04 P1 before M05, now it is further testing to see if this is the final solution for all jobs.

Thanks for the inputs and willingness to spend time on this issues.