THC config that works.

Hi,

For some reason on the config that I did install, the values for the step increments for the THC, the travel height, pierce height and switch travel does not seem to always take effect immediately after I have changed them. For example, at first when I adjusted the switch travel it did work somewhat, but usually when I did change it, it had no effect on the movement of the torch after the plate was sensed.
With the step increments I slowly increased the value once because the torch was not moving up fast enough, I then change the value to something ridiculous like 2 mm and the effect seem to have took place but when I changed it back to a much smaller value, the torch still moved as if the value was 2. It was only fixed once I restarted LinuxCNC.

I did however 'fix' the problem by changing the default values to the values that I desired, and that works perfectly now.

Regards

All works fine, thanks for the hard work and effort. I like the simplicity, but is there a way to adjust the velocity of the Z-axis when probing the plate. I use a z-axis with rack and pinion.
Ziggy

The F word sets maximum feed rate.

www.linuxcnc.org/docs/2.7/html/gcode/oth...html#sec:F-feed-rate

JT

The F for feed rate does not work when probing for material, so you need to set the correct speed in the .ini file for AXIS 2 under max_velocity.

Regards,
Tom

The F feed speed works for everything except G0, G33, G33.1 and G76. There is no ini setting for probe speed.

For example my plasma touchoff subroutine:

JT

Hi, Tom/JT.

I changed the max-velocity in the .ini file and also as per an earlier post by bubels I uncommented a line. (the Z-axis is controlled by thc.hal and not via G-code in the case of the Toma THC)

linuxcnc.org/index.php/english/forum/49-...works?start=20#50427

The Z-axis is probing correctly now.

I also cut a warped plate and it appears that the THC is working correctly.

A further question I have is if there is a way to switch off the THC when cutting small holes and arcs (via an M command?), or is this handled in the thc.hal?

Regards,
Ziggy

Hi
There is a corner lock speed in percentage that can be set at any time in the main screen that can be used to do just that, namely to not move the torch if the speed is below that set percentage of the actual feed rate. That is what i use for sharp corners and small holes, although doing small holes with a plasma cutter is not a good solution, the holes tend to be distorted and trying to drill them afterwards is a no go since the metal gets very hard on places where it got cut. Went through some drill bits just for the heck of it and the drill bits lost that game !!! I am talking new and unused Bosh HSS drill bits.
Give it a try and let us know how it goes.

@JT
This config does not use subroutines for touchoff, it has that implemented in the thc.hal file (not by me, by someone who spent a lot of time doing it, so i am thankful to whoever he or she was ). It does all the logic of moving torch down, finding the material, retracting back up to the pierce height, starting the torch, waiting for ARC OK signal and moving the torch further down to cutting height and starting movement, all this from a single M3 !
I actually have to remove everything that has to do with the Z axis from the NGC file so it does not wait for Z commands.
Regards,
Tom

tommylight wrote: This config does not use subroutines for touchoff, it has that implemented in the thc.hal file (not by me, by someone who spent a lot of time doing it, so i am thankful to whoever he or she was ). It does all the logic of moving torch down, finding the material, retracting back up to the pierce height, starting the torch, waiting for ARC OK signal and moving the torch further down to cutting height and starting movement, all this from a single M3 !

I'm struggling to get this to work on my machine. Everything appears to be fine but it does not probe the material with the z-axis. When I start the job it moves to the first point and then stalls. I'm guessing that it is waiting for the height probe. The Z-axis appears to move 3mm downwards but then simply stops.

I have previously been using my table without THC on a basic trivkins setup and it has been working fine. I've recently taken the plunge and have installed a THC unit along with your THC config. All signals seems to be correct, I have movement of all axis in correct directions and THC / Torch / Estop signals are showing in the display.

I'm obviously missing something. I had to invert a couple of signals including my torch signal, perhaps this is causing the issue?

I've attached my thc.hal file for reference.



And a shot of my machine. A real bare bones scrap pile build but works good enough for my use.



Any help would be gratefully welcomed

Thanks.

DM

Read the readme and howto file in the attached config, also see the post about removing a "#" somewhere in the config files, as it does cause some problems with the Z-axis when using a faster Z-axis ( i have all my machines running z-axis with a plain M6 screw via a belt from the stepper motor so i need a high step rate for Z).
There is everything necessary for making it work explained.
Do not modify the thc.hal beyond what it says in the howto, there is a whole lot of logic stuff that is there to automate the finding of workpiece, retracting the torch to pierce height at a set value in GUI, starting the torch, waiting for the arc ok signal, lowering the torch to cut height and starting movement, moving torch up/down as commanded by THC , stopping the movement if arc ok is lost etc etc.
Start over, read and modify to suit your setup, and it will work, without a hitch for many many years.
Regards,
Tom

Thanks for the quick reply Tom.

I did set everything up in accordance with the readme. The only changes made were the pins for my steppers / THC / Torch / Plasma and a line commented out for X/Y limits (I do not run limits on my machine).

I will first try to uncomment that line that you reference as I note that it's commented out in my setup, other than that if it does not work I will start again from a fresh copy just in case I have hanged anything else in my tinkering

One thought that crossed my mind - was this written for imperial measurements as I am working in metric, also where do I set the Z offset for the distance between the touchoff switch activating and the torch tip being at 0mm? It almost looks like it wants to work but only travels down 3mm.

Best regards

DM