A quick overview of QTplasmaC now it's deployed for production on the Spaceship plasma cutter at VMN.
QTPlasmaC is the current plasma configuration for Linuxcnc and becasue of that, when this video was published, it's only available in the development version of Linuxcnc (Master branch or Version 2.9). For more information about QTPlasmaC, please refer to the documentation. linuxcnc.org/docs/devel/html/p...
One of the reasons QTPlasmaC is so comprehensive is that Linuxcnc running on the PC is the motion controller. In most low cost alternatives it runs on a seperate microprocessor in external hardware. These systems simply do not have the resources of a fullblown CPU you find on a Intel based PC. Linuxcnc's motion controller manages all of the torch height control internally using its sophisticated PID controls. The THC then has full knowledge of all motion control parameters including velocity and acceleration information so it can do a much better job of managing the plasma process. QTPlasmac on Linuxcnc is a complete plasma controller, not just a THC.
This level of sophistication comes at a cost. That is, it must run on the Linux real time kernel (PREEMPT_RT). Historically this required patching the Linux kernel code and recompiling the kernel. To circumvent this, Linuxcnc has been distributed as a customised version of Debian Linux via an ISO download. However, being open source, it can be compiled from source on almost any Linux platform. More recently, the later distributions of Debian (Bullseye - version 11) include the PREEMPT_RT kernel in their distribution allowing it to be installed from a single line command (or through the graphical Synaptic package manager). It is my hope that when Linuxcnc V 2.9 becomes the production version that it will also be added to the Debian repositories which will mean the PREEMPT_RT kernel will be installed as a dependency automatically. I have been told there is some work towards this by the Linuxcnc and Debian developers.
The other cost in implementation is that Linuxcnc is a very flexible application that can be quite complex to implement so its not just a simple plug and play solution. QTPlasmac does everything it can to shield the user from as much complexity and the pncconf script supplied with linuxcnc to build a configuration for Mesa hardware has been extended to configure the environment for a QTPlasmaC system.
My view is that you only configure a CNC system once so conquering the added complexity of Linuxcnc is well worth it for the end result to get arguably the best Plasma controller outside of offerings from the major manufacturers such as ESAB, Thermal Dynamics and Hypertherm.
If you are considering building a CNC plasma cutter you may find the Plasma Primer I wrote as part of the Linuxcnc documentation of value regardless of if you adopt Linuxcnc to control it. linuxcnc.org/docs/devel/html/p...
Note that a post QTPlasmaC processor is included with Sheetcam and one is also available for Fusion 360.