Center Spot Sheetcam Post

So rephrasing;
a seperate component called spot-delay receives as input:
Spindle.2.on
Arc_Is_On
Spot-Time-Delay

And outputs:
Torch-On

Torch-on goes true when spindle.2.on is true and turns off Spot-Time-Delay after Arc-Is-On goes true.
Torch-On is or2'ed with the plasmac torch on output
Spot_Time_Delay comes from the Plasmac GUI Spot Threshold.

Actually, thinking about Stefan's problem today, I wonder if the problem was the F5 turned the torch off before the delay was over becasue the programmed move between M3 and F5 was quicker than the pause.

What if you did a tiny move on the Z axis after M3 like:
G1 Z -0.008 F1

That move will take 0.5 seconds (500 ms) to complete so it the spot would be over by the time it finished....

Looking at the performance of JTknives spotting has just about convinced me that voltage level is the way to go.

I think that using a timer has too many variables with relay response and machine response that it will not be consistent.

I will make a test comp but I won't get a chance today as I have other commitments.

As another data point, I have a one month old Hypertherm Powermax 45xp that shows the same behavior with spotting. When the torch moves to the first position, it moves to pierce height and fires the torch (110ms creates a nice dimple for me in 18g material). When the machine moves to the next location, it goes to pierce height but does not fire. The air is flowing from the first pierce. but when it tries to fire the second time, it turns off the air. Moving to the third pierce, everything works again.

Putting a G4 P20 between the first and second location does make it all work correctly. I tried a G4 P10 but it did not work. It seemed I had to wait long enough for the air to turn off (20 seconds). I suspect this is some "feature" of the machine itself but have not had a chance to call and ask Hypertherm.

I had considered just setting up my post processor to make a second tiny move and attempt to fire the torch a second time before moving to the actual second location. I think that would work but certainly is not very elegant.

Of note, the GUI showed 70V when the torch fired. For 18g material, the cut chart recommends 78V.

I use my own design board with a TLP222AF (solid state relay chip) to turn on/off the torch. The data sheet indicates a max turn on time of 2mS and max turn off time of 0.5mS.

Please let me know when you get the new version ready - I would be happy to test.

Steven

Is 110ms long enough for the machine to set the transfer signal, I am guessing here that it is not so the machine goes into a fail mode that requires time to reset.

Attached is the experimental plasmac component for voltage based spotting.

It uses Centre Spot Torch On Time (which is for this exercise Voltage Threshold) in the following ways:

• If the value is below the voltage reached for your Arc OK then this is the voltage the torch will turn off at.
• If the value is above the voltage reached for your Arc OK and the value is below 300 then the torch will turn off when Arc OK is received.
• If the value is above 300 then the torch will turn off (value - 300) milli-seconds after Arc OK is received.
  e.g. a value of 450 would turn the torch off 150 mS after receiving Arc OK

I know it is a bit funky but I want it to be reasonably flexible for testing purposes without too many changes.

I haven't added an arc fail timer yet so if the torch doesn't fire then it will just wait with the torch on signal active.

If you rename your existing plasmac.comp (which is probably in ~/linuxcnc-dev/src/hal/components) to plasmac.comp.old then copy this one to that directory then rebuild as you normally do then it should be installed.