Dwell starts before ARC ON / ARC OK

[spumco]

@mechcnc,

I have had the same problem for a couple of years. Primarily on plasma drilling operations with very short pierce delays (G4 P0.4).

As you described - first hole the torch fires, after that the dwell timer starts & expires before the ARC OK signal is triggered. Result is that all subsequent holes are not pierced.

Also have intermittent mis-fires during non-drill operations on very thin material (0.040") where the pierce delay is extremely short.

The wait-macro described in the post you linked hasn't worked for me. However, I did manage to get a different hack working today.

Mentioned in a couple other threads from around 2020 was a suggestion to issue a small movement command after M03 (torch fire) and before the G04 pierce delay. So I added the following after every M03:

M03
G91
G1 Z0.0001 F100
G90
G4 P0.4

And the misfire went away completely. Did ~150 drill pierces in one session today and no misfires.

Edited my sheetcam post processor and now sheetcam outputs every file with the above 'dummy' move and the pierce delay timer doesn't start until ARC OK is on.

So if you need a workaround while cncdrive and dezsoe work on a bugfix, you might try adding the above to a test program and see if it helps.

Sheetcam post edit:

post.Text ("\n M03\n")
post.Text ("\n G91\n")
post.Text ("\n G1 Z0.0001 F100\n")
post.Text ("\n G90\n")
if (pierceDelay > 0.001) then
post.Text (" G04 P")
post.Number (pierceDelay,"0.###")
post.Eol()
end

[mechcnc]

Thank you very much Spumco, I will try this. It seems like a great workaround for the time being.

Ive been trying Fusion 360 and ProNest until recently, and just now starting to experiment with the demo version of Sheetcam as well. It gives a lot more freedom of choice for the user compared to for example Pronest (which in the beginning feels bad because the learning curve is steeper, but in the long run its better for me). I will head over to their site and buy a license today.

Have a good day (or evening depending on where you are in the world)!

[gerius25]

Any luck solving the problem?

[mechcnc]

Ive tried the Z-movement command in between the M03 and dwell, but the waiting for arc OK only works sporadically for me. I have a switch in series with the relay that turns on the plasma cutter, so I can override the closing of the circuit which would turn on the plasma cutter. Sometimes when I turn the switch off (no arc will come from plasma cutter) UCCNC will just move forward with the program anyways. Other times, even within the same program, I hear the relay click and it starts to wait for the arc OK signal as intended.
Have you tried anything similar with an override switch, @spumco?

Is there an update on the horizon that will fix this, @cncdrive?

Br

[cncdrive]

Yes, we will release 1.2117 soon, it will fix it.

[mechcnc]

Great! Good work guys. Its nice to see a company listen to their customers and working on issues still. Have a good rest of the week!

Br