tangential knife along multiple layer height

It would be really nice if LinuxCNC could output a current heading angle for this application, but it isn't a 100% solution even if it could.

For a welder I feel that this might be better handled by a G_code filter that inserts a C axis move between each straight line move, and adds one to each arc.
This would also allow the possibility of turning off wire and arc at corners if the change in angle is enough to take a long time.

Yes, I can see how it would be hard for the A axis to remain synchronized with the xy. I'm not exactly sure what you mean by G-Code filter. I'm a bit familiar with people using spreadsheet to edit the g code but my trigonometry is not that good and I haven't found anything that will allow me to add a specific line beneath other designated G Codes automatically. I read on another forum of someone using a method called "postpost" that sounds similar to what you're describing. I'm honestly surprised that there isn't a tangential post processor that isn't just 2.5D

See this section on the INI config docs:
linuxcnc.org/docs/2.7/html/config/ini-co...html#_filter_section

The sample Python file is quite close to what you need. It would need to calculate an C-heading from any X and Y changes in a G1, G2 or G3 move and insert that before the original G-code line, and also add a through-the-move C rotation appended to the move itself.

Is there any other cam software for tangential knife except sheetcam ?

Hi Vre,

This for info. I hope you can use it.

The linuxcnc scurve planner has now tangential knife output value to hal.
The hal rotational output value could be coupled to a axis motor or device for rotation.

Within the the planner you can also benefit from the clothoid fillets, where the path
tends to be g3 continu, ideal for a drag knife application.

scurve planner is in master?
Have you completed it and is in working state?