Please Help me before I find Hammer

[Steve-m]

Hi Guys

Help Finally got plasma running working great apart from the last 20mm where the cutter turns off, I have tried on 5 or 6 different bits any ideas why please

retired maintenance fitter Im good with things i can hit with hammer or poke with screwdriver, or even electric glue together but software drives me nuts just cant get head around it

Thanks Guys

Acad 2002 drawings
Sheetcam Post
home made cnc running mach3
NVUM v2 bob




3089030891


https://youtu.be/Ahjgg9qeHjM

[Clive S]

Has the air pressure dropped too low as that could make it shut off ?

[Steve-m]

No no matter how big the piece i cut, cut always ends up 16mm short of start

[m_c]

What M-codes are you using to activate/deactivate the plasma? M3/M5?

Also, what happens if you change the feedrate?

[Steve-m]

What M-codes are you using to activate/deactivate the plasma? M3/M5?

Also, what happens if you change the feedrate?




tail end of code in picture

will try today to increase feed rate, strange when watching machine speed seems fine but when watching video its so slow to other videos ive wached


Cheers
Steve

[JAZZCNC]

It looks like the Z-axis is lifting before the end of the cut so you are losing the arc.?
Do you have THC.?

Post the code so can see it and I will try on our Plasma.

Yes, it's far too slow but that's not the issue.

[Steve-m]

It looks like the Z-axis is lifting before the end of the cut so you are losing the arc.?
Do you have THC.?

Post the code so can see it and I will try on our Plasma.

Yes, it's far too slow but that's not the issue.

Thank you will post in morning its in shed, Im so happy it even moves and cuts but will increase speed, sheetcam is all new to me old head dosnt like taking in new stuff

No THC just a floating Z

[Steve-m]

It looks like the Z-axis is lifting before the end of the cut so you are losing the arc.?
Do you have THC.?

Post the code so can see it and I will try on our Plasma.

Yes, it's far too slow but that's not the issue.

Tried at 2000mm min double speed and cut ended at 38mm before start

gcode from previous 1000mm min run if i can work out how to post eill email it to you


cheers

[Steve-m]

It looks like the Z-axis is lifting before the end of the cut so you are losing the arc.?
Do you have THC.?

Post the code so can see it and I will try on our Plasma.

Yes, it's far too slow but that's not the issue.

Tried at 2000mm min double speed and cut ended at 38mm before start

gcode from previous 1000mm min run if i can work out how to post eill email it to you


cheers

[Steve-m]

N0010 (Filename: SATTOP.tap)
N0020 (Post processor: Mach3 plasma THC with scriber and backlash compensation.scpost)
N0030 (Date: 19/02/2022)
N0040 G21 (Units: Metric)
N0050 F1
N0060 G53 G90 G40
N0070 (Part: frame top1)
N0080 (Operation: Outside Offset, 0, T1: Plasma, 1.5 mm kerf)
N0090 G00 X206.4310 Y39.4643
N0100 G28.1 Z10.00 F500.0
N0110 G92 Z0.0
N0120 G00 Z3.0000
N0130 G92 Z0.0
N0140 G00 Z3.0000
N0150 M03
N0160 G04 P0.5
N0170 G01 Z1.5000 F100.0
N0180 X207.1847 Y37.1340 F1000.0
N0190 X209.3655 Y36.0192
N0200 X217.6660 Y35.3548
N0210 X245.9485 Y33.1759
N0220 X245.9622 Y33.1747
N0230 X257.9121 Y32.0346
N0240 X276.3177 Y30.5178
N0250 X289.2243 Y29.4741
N0260 X295.7766 Y28.9034
N0270 X309.3535 Y27.6711
N0280 X323.5861 Y26.3420
N0290 X338.4898 Y24.9162
N0300 X358.9872 Y23.0171
N0310 X379.8710 Y20.8373
N0320 X379.8836 Y20.8359
N0330 X402.5664 Y18.0812
N0340 X402.5855 Y18.0787
N0350 X410.9306 Y16.8473
N0360 X420.5196 Y15.5642
N0370 X421.1701 Y14.8208
N0380 Y0.0000
N0390 X420.9139 Y-0.5645
N0400 X420.3204 Y-0.7433
N0410 X393.6534 Y2.8350
N0420 X352.7688 Y7.2934
N0430 X282.5512 Y13.7434
N0440 X195.5315 Y20.8610
N0450 X111.1952 Y27.5031
N0460 X83.5167
N0470 X83.1818 Y27.5820
N0480 X76.8552 Y30.7401
N0490 X38.5939 Y33.8571
N0500 X-0.0000
N0510 X-0.5303 Y34.0768
N0520 X-0.7500 Y34.6071
N0530 Y35.9360
N0540 X-0.5303 Y36.4663
N0550 X-0.0000 Y36.6860
N0560 X2.5750
N0570 Y38.5024
N0580 X2.7548 Y38.9896
N0590 X6.6447 Y43.5413
N0600 X7.2148 Y43.8040
N0610 X111.2247
N0620 X111.2875 Y43.8014
N0630 X140.6121 Y41.3375
N0640 X151.8055 Y40.4822
N0650 X168.4152 Y39.1533
N0660 X201.0605 Y36.6839
N0670 X209.3655 Y36.0192
N0680 M05
N0690 G00 Z10.0000
N0700 X0.0000 Y0.0000
N0710 M05 M30

[Steve-m]

here is a video of running at 2000mm min cut ends 36mm short of start

https://youtu.be/uNewULWj054

[Doddy]

I know nothing. Less about CNC. Less still about plasma. But I'd slave an LED on the NVUM output to trigger the torch and re-run, re-video a cut with the LED and torch in shot when it completes. If the LED on the NVUM extinguishes at the same time as the torch extinguishes, then the problem is likely one of the NVUM motion controller. The G-Code that you posted indicates no problems - once you get over the lead-in that it adds presumably to generate a clean cut from firing the torch. That the distance uncut lengthens when the feed rate is doubled suggests to my poor addled brain that the motion controller is running ahead of the pulse generation and shutting the tool (torch) off early.

Might be worth experimenting with a G04 instruction before the M05.

e.g. was:



N0680 M05
N0690 G00 Z10.0000
N0700 X0.0000 Y0.0000
N0710 M05 M30

becomes:


N0679 G04 500
N0680 M05
N0690 G00 Z10.0000
N0700 X0.0000 Y0.0000
N0710 M05 M30

[Doddy]

Hmmm, also, check out...

https://en.industryarena.com/forum/plasma-relay-switch-off-before-cut-complete-m05-early-digital-dream-uc300-usb--413288.html

[Steve-m]

Hmmm, also, check out...

https://en.industryarena.com/forum/plasma-relay-switch-off-before-cut-complete-m05-early-digital-dream-uc300-usb--413288.html

Thank you Doddy, will get some more steel and try but im sure that will sort it out
now need to read how to permantly tell sheetcam to add G04 to future projects

Thanks

[m_c]

That linked thread partially explains why I was asking what happens if you change the cutting speed.

It's all to do with how the trajectory (motion) planner calculates movement, and combines that with other non-movement commands.

Trying exact stop mode (not always ideal for plasma cutting, where you really want speed to maintained as much as possible), or a basic G04 pause might be enough to alter exactly where the M5 command actually gets executed.

[Steve-m]

ooops double post sorry

[Steve-m]

That linked thread partially explains why I was asking what happens if you change the cutting speed.

It's all to do with how the trajectory (motion) planner calculates movement, and combines that with other non-movement commands.

Trying exact stop mode (not always ideal for plasma cutting, where you really want speed to maintained as much as possible), or a basic G04 pause might be enough to alter exactly where the M5 command actually gets executed.

Thanks I changes speed from 1000mm / min to 2000mm / min and "undercut" more than doubled to about 36mm may look into changing NVUM to maybe a KK01 I have and a UC100, seems nvum has issues

[dazp1976]

seems nvum has issues


Say no more.
Nothing new there.
The amount of cnc forums containing people that have grief with NVUM/NVEM is ridiculous.

[Steve-m]

Say no more.
Nothing new there.
The amount of cnc forums containing people that have grief with NVUM/NVEM is ridiculous.

cheers seems i should have done a bit more reserch, I have a nvem too that drove me nuts trying to get to talk to computer thought that was me

[dazp1976]

cheers seems i should have done a bit more reserch, I have a nvem too that drove me nuts trying to get to talk to computer thought that was me

Somebody needs to sort it. It's getting a bit out of hand.
Get them all off sale and burn the lot!!.

[Steve-m]

Somebody needs to sort it. It's getting a bit out of hand.
Get them all off sale and burn the lot!!.

recomend replacements? I have a KK01, thinking i should start building a nice shed PC, and put my shed software on it mmmmm with a nice touch screen mmmm

[dazp1976]

recomend replacements? I have a KK01, thinking i should start building a nice shed PC, and put my shed software on it mmmmm with a nice touch screen mmmm

The only all-in-one I can comfortably recommend is the AXBB-E, based on my experience with the UC300eth unit.

My veiw these days is: Spend the money on the important 'brains' then make savings elsewhere.

Using a controller that's iffy and has mixed reviews may leave you fighting and trying to fix the wrong problem costing you more in the long run.

There are also decent options from cncroom for the UC300eth and ESS but these cost:
https://cncroom.com/store/?currency=USD