Another plasma component...

Just a heads up that Phill is still on the ball! A couple of days ago while conducting my own experiments, I observed by accident that a very short plasma pulse (maybe a millisecond or two) produced a very fine punch mark. I mentioned this to Phill so in less than a week, Phill has pushed an update that uses a third spindle (plasma, scribe and now centre punching) and he's included a variable on the GUI to set the time the torch remains on.

I have to say I can't wait to experiment with this new feature because my current spotting process is to wait until I get an ArcOK. I think this is pretty brutal by comparison!

How are you marking holes? I just use the drill function in sheet cam and have zero delay. It does a super fast pulse and makes a mark that looks almost identical to a center punch mark. Here is s video showing it in action. I think where I might be different is I have a very low arc OK voltage set.

JTknives wrote: How are you marking holes? I just use the drill function in sheet cam and have zero delay. It does a super fast pulse and makes a mark that looks almost identical to a center punch mark. Here is s video showing it in action. I think where I might be different is I have a very low arc OK voltage set.

Probably where we differ is that we are relying on the machine to give us an ArcOK and you are synthesising yours as your machine does not have a CNC interface.

Currently, for spotting I turn the torch off as soon as it sees an ArcOK but that is enough to pierce 2mm steel at 40 amps. It is more brutal at 120 amps on 16mm.

How this came about is I had a bug in my new ohmic sensing component and a probe signal was left enabled which Linuxcnc sees as an error. I suspect the torch was turned off on the next servo cycle.

I've been working on a new Ohmic sensing method which uses a Mesa THCAD-5 kindly donated by PCW to sense the voltage in the 24 volt circuit for the probe signal. The higher isolation afforded by the THCAD means there is no need to add relays and diodes to the circuit to protect things. In fact, its perfectly safe to leave the power supply connected all of the time but I've added an AC relay (blue one) to power off the power supply when not in use more to protect against any consumable corrosion that might occur on a water table.

JTknives wrote: How are you marking holes? I just use the drill function in sheet cam and have zero delay. It does a super fast pulse and makes a mark that looks almost identical to a center punch mark. Here is s video showing it in action. I think where I might be different is I have a very low arc OK voltage set.

Plus one for voltage derived Arc OK

I have changed the default pid-p gain back to 10 today and ran out a sheet of parts I had a problem with last time and they are cutting perfectly.

Hi, help please. I can’t use the Center Spot function, the machine goes to the spotting coordinates, makes a center mark and repeats this operation endlessly on one place until I stop the program.
What could be wrong?
The ARK-OK signal arrives. I still use the external THC from Proma.
I use installation from the LinuxCNC buildbot.
Thanks.