3D printer with multiple extruders

Grotius,

I do need to store positions for each extruder. I hope to call a tool change (Tx M6) and then extrude using G1 Ax.xx, call another tool change and then extrude on a different extruder with the same G1 Ax.xx command.

Rodw and tommylight, thanks for your feedback/ideas, I have searched for the multi spindle work and found this post which looks promising:
forum.linuxcnc.org/10-advanced-configura...thon-lessons-learned

I have a lot of learning to do so links to documentation that will be helpful such as how to remap stepgen outputs on an M6 would appreciated.

I know nothing about the tool changer side of things.

If you have a look through your hal file, you will see that there are some axis.A.xxxx signals mapped to stepgen.N signals. So your goal is to change those mappings to a different stepgen number. There are probably other ways but I think if I were doing it, I would write a component that received a 1,2,3 to select your extruder number and select the correct stepgen. If you wanted to select the extruder from gcode, M68 would do the job nicely. Then roll it all up into a toolchanger that knows the extruder offsets.

I'd have to think it through a bit but as inputs, you probably would have the selector pin and a set of Axis.A pins. and as outputs you would have 3 sets of stepgen signals. Then you just copy the inputs to the correct set of outputs that point to the stepgens. There may also need to be a feedback signal from the stepgens back to axis.A to complete the loop.

Can any of the slicers output the extrusion feed in incremental rather than absolute mode? That would make things much simpler.

I think you should have s look into marlin. They have solved quite a lot and a slicers like simplify3d and cura etc. have quite an uniform way to produce G code for multimaterial.