PlasmaC torch starting problem (Solved with help from the famous three)

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13 Mar 2020 16:24 - 25 Apr 2020 13:17 #160040 by Clive S
I have a pilot arc start machine the torch will always fire on the first cut but on the next cut it will error out with "valid arc lost program is paused"

Before it errors it does the probe OK the float switch triggers the led and very briefly triggers the torch-on led.

Then pressing pause it will do another cut OK then the same problem happens for every cut.

I have tried altering the OK Low Volts between 5-30 . I notice that after a cut the Ark Volts hover around 2-20v but when the air purge stops is then goes to zero

Vid from my Nas Drive photos.app.goo.gl/aPzSCVR5uQSApnKK6
Last edit: 25 Apr 2020 13:17 by Clive S. Reason: added text

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13 Mar 2020 18:45 #160068 by bbsr_5a
you need to increase the wait between retry time
maybe your plasma needs some seconds to get a clear refire arc signal
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13 Mar 2020 21:47 #160083 by phillc54
I think bbsr_5a is correct, try increasing the Arc Retry Delay, maybe Arc Fail Timeout needs increasing as well.
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13 Mar 2020 22:30 #160088 by tommylight

I have tried altering the OK Low Volts between 5-30 . I notice that after a cut the Ark Volts hover around 2-20v but when the air purge stops is then goes to zero

That is to low, i have it set to 80V min and 150V max, wired to an ISKRA plasma source, i was pleasently surprised that it never failed to detect a valid arcok. The cut voltage is 125 to 135 depending on speed and thicknes.
Try this:
-Load gcode, start the gcode with the plasma source OFF, measure the distance from torch to material.
-Power on the Plasma
-Start the gcode from beginning, let it make the first cut, switch off the plasma, measure the distance.
If the distance is the same, all is good, but do try to make that distance from 2 to 3mm and see if the consequent cuts succeed .
All this only after you check the previous replies.
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13 Mar 2020 22:50 #160091 by Clive S
Many thanks for the above comments. I will test them out in the morning :) and will report back.

I think arc retry is set for 1 second

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14 Mar 2020 12:40 - 14 Mar 2020 16:00 #160165 by Clive S

I think bbsr_5a is correct, try increasing the Arc Retry Delay, maybe Arc Fail Timeout needs increasing as well.


Phill I have tried the arc retry delay to 20 secs with no joy. But thinking about it does the retry delay work for pilot arc.

I have also tried with the arc fail from .5 to 5 secs with no luck.

It always works after an arc fail then the Z goes up and waits until pause is pressed, If I wait until the machine has stopped the air over-run (at this point the volts drop to zero) at this point pressing pause works and completes the cut then I have the same prob at the next section cut.

I am beginning to think this is a problem with the plasma cutter as until the air stops the volts float around anything between 0 to 18 then when the air stops it then holds steady at zero.


Edit: Phil . Trying to test the above I made 3 small circles with shapes and array I saved the gcode to the standard folder and then edited it with G4 P15 after the first cut to see if the 15 sec delay (ie long enough for the air to stop and volts get to zero) but when this was reloaded it purged the g4p15 out of the code. So how can I get a pause in the code between the cuts to test ?
Last edit: 14 Mar 2020 16:00 by Clive S.

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14 Mar 2020 22:32 - 14 Mar 2020 22:48 #160219 by phillc54

Phill I have tried the arc retry delay to 20 secs with no joy. But thinking about it does the retry delay work for pilot arc.

The plasma source should have no effect, the Retry Delay is the amount of time from a failed arc until it attempts to restart the torch. Arc Fail is the time from when the torch was turned on until a failure is reported if the arc is not within the set parameters.


Trying to test the above I made 3 small circles with shapes and array I saved the gcode to the standard folder and then edited it with G4 P15 after the first cut to see if the 15 sec delay (ie long enough for the air to stop and volts get to zero) but when this was reloaded it purged the g4p15 out of the code. So how can I get a pause in the code between the cuts to test ?

That seemw odd, I will take a look later today.
Last edit: 14 Mar 2020 22:48 by phillc54. Reason: typo

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14 Mar 2020 22:40 #160222 by tommylight

I am beginning to think this is a problem with the plasma cutter as until the air stops the volts float around anything between 0 to 18 then when the air stops it then holds steady at zero.

Seems to me that is pretty normal, while the compressed air is passing through the conductivity is higher and the THCAD is sensitive enough to count for that.
Check the ARCOK light while that is going on, if it is ON while the air is still running and the Torch Volts show 0 to 18V, there is most probably your problem, so raise the MIN arcok voltage to something like 60 to 80V.

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14 Mar 2020 22:53 #160225 by Clive S

I am beginning to think this is a problem with the plasma cutter as until the air stops the volts float around anything between 0 to 18 then when the air stops it then holds steady at zero.

Seems to me that is pretty normal, while the compressed air is passing through the conductivity is higher and the THCAD is sensitive enough to count for that.
Check the ARCOK light while that is going on, if it is ON while the air is still running and the Torch Volts show 0 to 18V, there is most probably your problem, so raise the MIN arcok voltage to something like 60 to 80V.


Thanks for the feedback Tom. I have already tried setting the "OK low volts" to 90v I take it that OK low volt IS the same as min arcok
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14 Mar 2020 23:05 - 14 Mar 2020 23:06 #160229 by Clive S

The plasma source should have no effect, the Retry Delay is the amount of time from a failed arc until it attempts to restart the torch. Arc Fail is the time from when the torch was turned on until a failure is reported if the arc is not within the set parameters.


If I am not mistaken the retry delay does not (BUT i will check in the morning) restart the Z action ie. coming back down for a fresh probe

This is why I would like to put a delay in the actual gcode as a test. That would I think be a good test.

Just for clarity with the gcode I noticed with using shapes that it puts in a G1 X 0.000001 near the end of the code just after a g90 or g91 and if I edit that out and save the file to desktop then reload it it still puts it back in.

I do appreciate all the work you have put into this. Clive
Last edit: 14 Mar 2020 23:06 by Clive S. Reason: added text

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