Arc OK intermitent issues on torch fire

txtrone wrote:

rodw wrote: QTPlasmac supports the laser but I have not played with it on real hardware. Maybe over Easter.. But I don't have enough pins on the gantry to turn it on and off from the GUI

Rod, as your attorney I advise you to install more pins on the gantry.

Which is why you have a DB15 cable not a DB9 like I do!
You have Spaceship V2 hardware !

snowgoer540 wrote: Lastly, I was reminded that the diagram shows the shield wire going to ground. That is not correct per PCW:

forum.linuxcnc.org/plasmac/39899-doing-o...h-one-thcad10#180352
forum.linuxcnc.org/plasma-laser/40712-th...ions?start=30#197468
forum.linuxcnc.org/plasma-laser/40712-th...ions?start=30#197472

I just read through all of that and my head is spinning. Those posts covered earth, fire, and water without any sort of consensus in the end. "Put the shield here, no put it here, fuse it, no don't fuse it, mine caught on fire, etc, etc"

snowgoer540 wrote: However, I am unsure what that looks like in the diagram because the posts seem to be a bit contradictory (in one post he says +in of the THCAD, and in the other he says "closest to the workpiece", and they are not the same connection...

The post directly after that one is from tommylight who had this to say. "FYI, i never connect the THCAD shield to anything, no issues so far."

The THCAD shield connection is not terribly important unless you have a very high EMI environment. For a high EMI environment (like HF start plasma sources) the shield should be connected to earth ground. For normal plasma the shield can be connected to the + input (low side of the voltage divider from the plasma source). This will result in the lowest amount of hum and noise in the signal.

PCW wrote: For normal plasma the shield can be connected to the + input (low side of the voltage divider from the plasma source). This will result in the lowest amount of hum and noise in the signal.

Thanks PCW! Stay with me for a sec. Can you clarify what "+ input (low side of voltage divider from plasma source)" is. I am using a hypertherm85. I have six wires coming from the CPC port to the THCAD. Are you saying to connect the shield wire in the interconnect cable between the hypertherm and the THCAD to the +input along with the 24+ from the isolated power supply?

txtrone wrote:

snowgoer540 wrote: Lastly, I was reminded that the diagram shows the shield wire going to ground. That is not correct per PCW:

forum.linuxcnc.org/plasmac/39899-doing-o...h-one-thcad10#180352
forum.linuxcnc.org/plasma-laser/40712-th...ions?start=30#197468
forum.linuxcnc.org/plasma-laser/40712-th...ions?start=30#197472

I just read through all of that and my head is spinning. Those posts covered earth, fire, and water without any sort of consensus in the end. "Put the shield here, no put it here, fuse it, no don't fuse it, mine caught on fire, etc, etc"

snowgoer540 wrote: However, I am unsure what that looks like in the diagram because the posts seem to be a bit contradictory (in one post he says +in of the THCAD, and in the other he says "closest to the workpiece", and they are not the same connection...

The post directly after that one is from tommylight who had this to say. "FYI, i never connect the THCAD shield to anything, no issues so far."

Like I say, lots of opinions, lots of “definitely do or don’t do this” sometimes when the person giving advice doesn’t even have and experience with the brand of.. whatever... that is being discussed.

So, the best you can do is read the information out there, consider it, and do what works best for you.

I will say, I don’t understand anyone recommending to not use a fuse. That just blows my mind. Cheap insurance. Worst case you size it too small and need to get a bigger one. Best case you don’t set your wiring on fire and burn down your dwelling.

I do sometimes feel bad for new people trying to wade through all of this. But I guess that’s part of the learning process. A lot of us were figuring it out together as we went along. Still are, honestly.

txtrone wrote:

PCW wrote: For normal plasma the shield can be connected to the + input (low side of the voltage divider from the plasma source). This will result in the lowest amount of hum and noise in the signal.

Thanks PCW! Stay with me for a sec. Can you clarify what "+ input (low side of voltage divider from plasma source)" is. I am using a hypertherm85. I have six wires coming from the CPC port to the THCAD. Are you saying to connect the shield wire in the interconnect cable between the hypertherm and the THCAD to the +input along with the 24+ from the isolated power supply?

That was for THC use, for Ohmic sensing, there is no connection to the CPC port at all