Ideas on STRATEGY for optimizing stringing parameters?  

RE: Ideas on STRATEGY for optimizing stringing parameters?

hi,

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

regards,

Friedhelm

RE: Ideas on STRATEGY for optimizing stringing parameters?

Hoping to resurrect this thread, get any updates or conclusions you may have reached, & spark more conversation. I have a model that with some small commercial success, & it has been printing just fine. But one of the customers wants a different color, & even though I'm using the same brand & grade of filament & have dried it thoroughly, it prints with lots of stringing where none was experienced before. I'm starting to experiment with temp, retraction length, & traction speed, but was wondering if there are other parameters to include.

I'm an industrial/process engineer, so I relate when you speak of exploring the parameter space. It occurs to me that the space may be different for each variation of filament, including color.

Posted by: @fuchsr

[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.

 

RE: Ideas on STRATEGY for optimizing stringing parameters?

Luckily, I haven't run into any significant stringing issues lately that couldn't be solved by either drying the filament, running at a lower temperature, or with the help of a heat gun. I did play a bit more with various stringing tests at the time but what I noticed was that they "worked" with most filaments (in which case default settings usually did a good job anyway) or didn't do anything with "difficult" filaments, as in showed no improvement at whatever settings.

RE: Ideas on STRATEGY for optimizing stringing parameters?

Like others, I've done the stringing dance for years, but of late I find that filament dryness is the overall king of print quality issues, including stringing.  In almost all cases the preset filament profiles get you really close, and @friedhelm-b lists a pretty good filament calibration routine to improve speed and quality, but if you  move down the path of filament calibration with wet filament, you'll be nothing but frustrated. 

RE:

@fuchsr @Lynn

I have a model that I've been printing & selling: both on the MK3S & Mini. It prints a little faster on the Mini & it seemed the quality was just a bit better (with Input Shaping I think). I'm using Prusament PLA in several colors: Mystic Green & Brown, Vanilla White, & Galaxy Silver. A customer wanted it in red, so I ordered Prusament Lipstick Red. I dried it thoroughly before attempting to print, but they came out looking like fuzzy red Tribbles from Star Trek (the model has smooth geometry). I did a 3-factor experiment with temperature, retraction, & the new z-lift ramp settings. I can't find a stable process window to control the stringing even a little bit. I could use a heat-gun on the whiskers, but the models surface is also crap. I've got print-in-place hinges & snap-fits that don't work at all.

I tried some Jessie red PLA from Printed Solid, using the stock Prusament PLA profile, & it prints just fine on the Mini, but it's a little more brittle than Prusament. If I go this route, I'll need to refine the model to be more robust in some thin section.

I took the original model & printed it in Prusament Red on the MK3S with the stock Prusament PLA profile - it prints perfectly. I'm a bit disappointed because I have other work to print on the MK3S. If I order volume increases for the red parts, I may need to add capacity. I was hoping I could build a Mini farm, but not if I can't resolve the stringing.

RE: Ideas on STRATEGY for optimizing stringing parameters?

One brand that has been consistently well behaving for me is Overture, on Minis et al.