Extruder micro-stepping with a mixing hot end.

[deckingman]

For anyone who may be interested, I have just re-visited this topic and run some "real world" tests. It's all described here https://somei3deas.wordpress.com/2019/07/22/mixing-hot-end-extruder-micro-stepping-revisited/

[DocTrucker]

Off topic slightly but was it you that discussed earthing the hotend/nozzle? Was this just part of a fault finding exercise or did it cure something? Covered in a blog of yours?

[deckingman]

@doctrucker said in Extruder micro-stepping with a mixing hot end.:

Off topic sligjtly but was it you that discussed earthing the hotend/nozzle? Was this just part of a fault finding exercise or did it cure something? Covered in a blog of yours?

No - that's the first time I have ever heard that suggestion.

[Phaedrux]

I'm curious if this would actually work:

One possibility would be to use a post process script to change the extruder micro-stepping to a low value before the retraction and restore it after the subsequent un-retract move. But as there was no discernable advantage to using 256x, then the simplest thing is just to limit the micro-stepping to 128x.

Is microstepping changeable on the fly without any pauses or stutters or anything?
Would the change be executed in time for the retraction move?

Perhaps another good reason for moving to 0.9 degree steppers for the extruders?

I think in addition to mixing hotends, those printing high detail small objects like miniatures could be effected as well. Low layer heights, small nozzles, lots of round shapes, etc could lead to under and over extrusion which wouldn't appear as a color difference, but could perhaps effect surface finish?

Thanks for sharing your findings.

[deckingman]

@phaedrux Ref changing micro stepping before and after retraction - dunno. In theory it should work. Maybe one day I'll try it (or you can)🙂
Ref 0.9 degree motors - makes no difference. 128x using 1.8 degree motors is the same number of micro steps as 64x using 0.9 degree motors. It would only be of benefit if you need higher resolution than 256x with 1.8 degree motors.
Ref small, detailed parts. I agree that there could be some benefit. However, you would need a large number of consecutive segments that all got rounded in the same direction, to see signs of under or over extrusion I'd have thought.

[Phaedrux]

@deckingman said in Extruder micro-stepping with a mixing hot end.:

However, you would need a large number of consecutive segments that all got rounded in the same direction, to see signs of under or over extrusion I'd have thought.

Yes I think you may be right there. It would probably get drowned out by filament diameter variations as well.