Scaling with filament change

mikeabuilder

I'm writing my config.g files for my filaments. One thing I decided would be cool to add is scaling to compensate for material shrinkage. In this way, I don't need to remember scaling factors to put into my slicer, it's always there.

As a result, I want to add an M669 command to the config.g in my material with the scaling in my matrix. Unfortunately, I have an M671 command in my sys/config.g file and an M669 needs to come before any M671.

I'm thinking I might use an M579 instead. My printer is a CoreXY but I"ll be scaling both X and Y by the same factor, so I'm thinking I should be OK.

Thoughts on this?

I know this whole thing is a dumb idea if I'm switching filaments in the middle of a print and the materials have different shrinkage rates. But other than that?

paralepsis

@mikeabuilder This isn't precisely what you're trying to do, but I also use filament configurations, as follows:

Turn on volumetric extrusion in your slicer.
Put "M200 D1.75" in your slicer configuration to get into volumetric extrusion mode. This is necessary to work around a quirk (IMO) in how RRF handles volumetric extrusion.
Somewhere after that M200 in your slicer configuration gcode, call "M703" to get fire off the appropriate config.g for your filament.
In the appropriate filament config.g, set actual filament diameter, extrusion multiplier, retraction, and pressure advance:

M200 D1.74
M221 D0 S90.3
M207 S0.5 F2400 T1800 R0 Z0.0
M572 D0 S0.04

In retrospect, this could probably be done w/out volumetric extrusion by assuming a 1.75mm filament diameter and relying solely on extrusion multiplier, but I haven't confirmed.

Maybe this will help as you plan.

Phaedrux

Do no mess with volumetric extrusion unless you also configure your slicer to use volumetric extrusion and test that it works. It never really took off and I don't think it even works correctly to be honest.

Extrusion factor is probably the safer way to go.

dc42

@mikeabuilder yes using M579 would be a better choice IMO.

paralepsis

@phaedrux FWIW I'm using volumetric with PrusaSlicer and SuperSlicer exclusively, no problems using the scheme above, but I'm likely to revert given how unpopular it appears.

mikeabuilder

Thanks for all the feedback, everyone.

I don't think volumetric scaling would compensate for part shrinkage because it would adjust the amount of filament extruded but not the location ofthat filament. It also sounds tricky and is also something done in the slicer and I'm trying to keep the slicing simple.

In the end, I used the M579 command and it's working perfectly as I expected because I'm scaling both X and Y by the same amount. If I was trying different scaling on each axis, my CoreXY would scale the print in undesired ways.