Am keen to connect with anyone who has Freecad working well with their SLB or similar.
Am happy with Freecad vr 1.1.3 (latest at August 2026) for what I need for design, less so with CAM with grblhal compatibility. I do like the workflow from design to CAM in a single tool.
Sometimes the output gcode works good, other times i spend too much time trying to sort it. Sometimes cgode editing to clean out anything not compatible or searching deep for alternative Freecad CAM job approaches. Arcs not calculating closed correctly is a common issue.
Has anyone used a grblhal specific post-processor, or edited the default one for better support with the SLB? Or any other recommendations/suggestions?
Thanks Jason
Current setup is the LongMill mk 2.5 with SLB.
ps - with Freecad improving, and much easier to learn (including with LLMs), getting CAM workbench to work well with Sienci Labs controllers really would be great.
Ok, so I’ve gone a bit deeper and see that Freecad is introducing some big changes and improvements for CAM in next upcoming releases. This is great, but until I learn more and figure out the new development builds and how they work in practice, I’m still a bit stuck.
Also, I’m need to keep opensource for a few reasons including our Kiwi dollar being worth pennies.
And so…
Since my post yesterday, I have figured out more issues between the grbl post processor and grblhal. I have a developed a LLM prompt to use to clean up my gcode and have it ready for my SLB. I’ll post back how this goes and would be happy to share. I use LLMs a lot at work and have confidence in getting something safe that works reliably. Early review of the ‘grblhal compatible’ gcode looks good. Included bCNC formatting (only just discovered that now) and some personal preferences for quality of life improvements.
I was also interested in starting to use Freecad but maybe it would be better to start with Fusion if Freecad doesn’t have some basic kinks out for CAM. You can actually download and use Fusion for free until you start making $1k in revenue and is for non-commercial purposes.
Cheers David, I’ve been on 1.1.3 since it came out. Later this week I will start testing the Dev builds to see how the CAM workbench is improving.
That all said, I really like the LLM prompt I have. Basically, it’s ‘Skill’ is to analyse my Freecad grbl gcode and tidy it up to be grblhal compatible for the SuperLongBoard. It has been working really good. What the LLMs can do with gcode is so good now. I’m only doing this on simple items, but it’s just so helpful and truly got me out of a bind. Also the LLMs have made learning Freecad so much easier. If I forget a concept, it’s like having a tutor available on demand.
