Since I received, built, and have been using my new 3d printer, one of the challenges it has faced is the reliability of the filament sensor. Admittedly, this is one of the big selling points for the Prusa i3 MK3s – the filament sensor auto-detects filament and can pause a print when it runs out, along with auto-loading new filament simply by inserting the end. Unfortunately, the manufacturing tolerance for this function is particularly sensitive, and as assembled, it simply didnt work.
I tried a few hacks – inserting shims and making adjustments – but ultimately I just disabled the auto-load and switched to a manual loading. This was fully workable, but did nullify the out-of-filament feature. If I was running low, I had to stay at the printer to manually load the next spool at just the right time.
However, thanks to Stirlsilver and Thingiverse (https://www.thingiverse.com/thing:4047773), this issue is no longer a concern. Posted on the site is his redesign of the function – basically ignoring the mechanical switch and admittedly overly complex design – and replacing it with a direct scan of the filament itself. The part ran about 30 minutes to print, and only about 10 seconds to install, and immediately the sensor was functional. Simply by rotating the sensor 90 degrees and repositioning it, this solution resolves a long standing issue.
After a few tests, including short filament and swapping filament, it is working great. The only drawback is that this doesn’t work for transparent or very lightly colored filament – I ran some temperate sensitive color changing filament, and it misread the state when the filament was white. For me, this is fully workable – I will just switch to manual for the rare times those materials are used. For my normal grey or black filaments, we are fully working.
