It would be tricky to do and might require a custom tool, but I wonder if in a case like this, knurling might work better than hobbing. Ultimaker uses knurled drives, and they seem to be much more resistant to grinding filament and clogging up the teeth, but theirs have been shown to slip so as to increase the required steps/mm when back-pressure increases from trying to extrude faster, and driving the filament from both sides might solve that problem.
Regarding grip, i used a much more coarse thread for my bolts than most, usualy M8 or even bigger. That made for perfect grip, but still single sided. It works ok, but the handling of the extruder is cumbersom. https://www.youtube.com/watch?v=1uW7kFf2ekI&list=UUUC07LIz2XdeOoV97NJd1YA
UPDATE : I have spoken with @Ignacio_Garcia from @RECREUS_3D_PRINTING and it unfortunate that the beta gears that I have been testing have a manufacturing flaw resulting in the hobbing being too shallow on this prototype. The production version will have this corrected. May I add, that even with this flaw, it still has been performing flawlessly (sorry).
Yes, unfortunate the first sample order, only 2 pairs of gears works with Pla and Abs, but the other 3 pairs the groove teeth are not sharp enough, the problem has been solved for production version.
We will notice when it will be ready. ( improving mode)
Björn Marl, yes, I am using 1.75mm filament.