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