Constantly and Quickly Surging Fans
Hi, all! I'm hoping someone can help me out here, or at least confirm that what I've found is a legit bug with Prusa Slicer?
Recently, I've been having trouble with my fans surging from 20% to 100% repeatedly at a very high frequency (8900 speed changes within a basic 90 minute print, averages to 1.6 speed changes _per second_). It seems like might be somehow related to dynamic overhangs, but even dynamic print speeds has no effect (on the fan bug). Disabling dynamic fan speeds, the gcode improves very slightly, but the problem persists.
Below is an image of the part I'm printing (the smaller part has a 45* overhang, but (pretty sure) the fan problem persists when printing layers above that, too)
Also a screenshot of my overhang-related settings and a snippet of resultant g-code.
The very last image is the "improved" gcode after disabling dynamic fan speeds, but you can see the pulsing/surging is still present.
Any info or suggestions you might have are appreciated, and please let me know if I can provide any more info about my setup!
RE:
Similar problem here slicing this test file https://www.printables.com/de/model/342481-overhang-test-regular with 2.8.0 and dynamic fan speeds enabled.
example of fan speed changes, in total I get 18069 fan speed changes on a 15min print
I tried different settings this is what I'd want to realize:
example:
G1 F1913.824 M106 S122.4 G1 X148.525 Y135.617 E.0096 M106 S94.35 G1 F1630.309 M106 S142.8 G1 X148.983 Y135.275 E.01018 M106 S94.35 G1 F1491.463 M106 S153 G1 X149.475 Y135.1 E.0093 M106 S94.35 G1 F1486.389 M106 S132.6 G1 X150.152 Y135.053 E.01209 G1 X150.392 Y135.094 E.00434 M106 S94.35 G1 F1650.72 M106 S135.15 G1 X150.872 Y135.213 E.00881 G1 X151.254 Y135.423 E.00777 M106 S94.35
RE: Constantly and Quickly Surging Fans
Try lowering Fan Settings > Bridges Fan Speed? It is 100% on those screenshots.
Otherwise report on GitHub.
See my GitHub and printables.com for some 3d stuff that you may like.
RE: Constantly and Quickly Surging Fans
Already open issues on GitHub about excessive amounts of fan speed commands. A couple of them at least iirc. Don’t have time to search at the moment for the exact links but go add to them.