Ideas on STRATEGY for optimizing stringing parameters?
[cross posting to MINI and Mk3S forum because it's not machine specific]
Never really had serious stringing issues that a simple temperature adjustment or my trusted heat gun couldn't take care of. Now I'm finding myself doing some production runs with 3D Solutech Chocolate Brown with too much stringing to accept.
What I'm interested is NOT just a list of parameters to modify. I know that. I'm also not interested in anecdotal suggestions of specific parameters. It all depends on your specific material.
What I'm interested in is ideas (ideally experimentally verified one -- yes, I used to be a scientist) to optimize a systematic exploration of parameter space.
What I am assuming here is that the quality of the print (aka least amount of stringing) is not driven primarily by one parameter (happy to stand corrected on that assumption) but that there will be local optima defined by specific combinations of parameters.
Let's simplify for the sake of argument and posit that only temperature, retraction length, and retraction speed were relevant (which I know is wrong). That alone would create a three dimensional search space: Vary temperature, vary retraction length, vary retraction speed. IF temperature were the main driver, I could simply find the temperature with the lowest amount of stringing, then play with the other two dimensions to fine tune the results. However, I don't have any evidence to believe that that's the case. So while say 210 degrees may give me the best results at a constant 3 mm retraction, it's not inconceivable that 200 degrees with 4 mm retraction would give me better results. Or 205 degrees, with 2 mm retraction, and a higher retraction speed.
Of course there are plenty of algorithms to search multi-dimensional spaces for local maxima or minima, but in the end we have to translate those into experimental setups. Using a fake multi-extruder setup in PrusaSlicer I can test some of these dimensions in one print, such as retraction length on the x axis and retraction speed on the y axis. Others such as temperature will require several prints. And of course it's not just three parameters, which one may probably explore exhaustively, but more 6 or 7.
So I'm interested in hearing what strategies folks are deploying to optimize print parameters (with a particular interest in stringing). Anything different than linearly testing each parameter -- and potentially overlooking a multi-dimensional local optimum?
And of course if anyone can give me reason to believe that one parameter alone is driving the system's behavior and everything else is just nuances, I'd die a happy person, too.
just speaking for myself, I'm running the following steps in this order to calibrate a new filament:
- determine max volumetric speed
- calibrate extrusion multiplyer
- calibrate temperature
- calibrate k-factor
- print a flat surface and visually calibrate overlap of infill and perimeter in prusa slicer settings
- check dimensional accuracy (usually i get tolerance of 0,1mm)
- do a quick stringing test
- if the quick stringing test is not satisfying, do a intensive stringing calibration