Random Questions on setup

So, we ran our first production run using the 7i96s, THCad2 and QTPlasmac, and it was like jumping in a Cadillac after driving a pinto. Night and day between Mach4 and linuxcnc. Soo happy I invested in switching electronics over and making the switch. 

Couple of issues I encountered and would like to get corrected.
I don't think i have my Z set correctly no issues in cutting or height control, When the machine is homed for the first program run, it runs up to the Z+ Prox / Z home from their it drops down to I'm guessing an offset I put in. it than drops down about 2 inches and zeros the Z drive. not a big deal but when I'm trying to line the torch up it won't go below 0.00 is it better to let the Z axis home off the probe or an upper limit. 

On Probe it does this weird little double probe you can watch it come off the probe switch than go back to it than proceeds to cut height. is this normal or am I missing something in the settings?

Randomly had no arc signal from the Hypertherm 65. this was closer to the end of the program about 45 minutes into cutting. I'm guessing it was a Hypertherm issue as I turned it off reseated the CPC port and it came back no issues but eventually did it again. I'm running Mode 1 in QTPlasmac which I believed was the setting when there is a separate ARC ok Signal?

During that no arc ok phase I also noticed that QTPlasmac will attempt three times to fire the torch after the third round of that it powers off with the screen switch and resets the program. Is this normal if it is, is there a way to change the number of rounds it will go through before resetting the whole program. 

Appreciate any info on these Items 

If the Hypertherm Arc OK output is from a relay (as opposed to a Optocoupler),
you may need to add a load resistor to provide the "wetting" current the relay
contacts require. (This current may be as much as 100 mA so requires say a 220 Ohm
5W load resistor)

 

FlaredFins wrote:

I don't think i have my Z set correctly no issues in cutting or height control, When the machine is homed for the first program run, it runs up to the Z+ Prox / Z home from their it drops down to I'm guessing an offset I put in. it than drops down about 2 inches and zeros the Z drive. not a big deal but when I'm trying to line the torch up it won't go below 0.00 is it better to let the Z axis home off the probe or an upper limit.

Some info on the Z axis:
linuxcnc.org/docs/devel/html/plasma/qtpl...plasma:initial-setup
 

On Probe it does this weird little double probe you can watch it come off the probe switch than go back to it than proceeds to cut height. is this normal or am I missing something in the settings?

The two most common reasons for this are:

1. The Probe Height is set too high compared to Safe Height.
2. Probe Height is set below the material height and the first probe trip is done at Setup Speed then the second trip is done at Probe Speed.

During that no arc ok phase I also noticed that QTPlasmac will attempt three times to fire the torch after the third round of that it powers off with the screen switch and resets the program. Is this normal if it is, is there a way to change the number of rounds it will go through before resetting the whole program.

Not sure what you mean by resetting, the program should go into pause mode after the failed attempts.

linuxcnc.org/docs/devel/html/plasma/qtpl...lasma:parameters-tab

I Planned on digging more into the manual today. a lot of features I think I saw during cutting and some items I would like to change if it's possible for my screen layout.
By resetting I mean instead of a pause it takes you back to line 1 of the G-code. I'm going to look into what Tommy wrote in his post.

On the Probe item. I have some confusion and it will probably be cleared up when I get my Z axis set correctly. But what happens when there are conflicts in your post vs what is set in parameters. Which supersedes the other. qtplasmac or the Gcode in the file?

Thanks Tommy, Ill be attempting to dial in my Z axis today. And dig more into the ARC ok signal. would like to know exactly what hypertherm is using to get that contact to close and allow the signal to come through. if it is a relay or something else closing.

 

Another question I left out yesterday not an issue but more of curiosity. while cutting I noticed one of the plates showing in red that it had been cut already and then it went back to white like it hadn't been cut yet. this is more than likely in the manual but thought I'd ask. Is this also part of cut recovery so as long as it is still red that's how far back you can go for cut recovery?

it didn't cut it again; it just removed the red highlighted lines as it progressed through the G-code.

Went through and set Z axis, I'm guessing because it homes to the + its confusing the heck out of me. 
POS = 7.00
NEG = 0.00
Final Pos = .125
Home switch location = .125
Search Direction = POS
Home Latch = Opposite
This appears to work except when it homes it does its magic dance it sets the position to .317. OK.... go to do a probe test and it drops to around -.63 and says no no no your going below the limit. 
why isnt it setting the position to 6.875