filament sometimes not making it to nozzle and printing without loading  

Re: filament sometimes not making it to nozzle and printing without loading

printing will be going fine but sometimes the filament doesn't make it all the way down the extruder tube, and the printer starts printing without the filament loaded.
Anyone have this happen and fixed it?

The load distance doesn't seem to be perfectly consistent, so if there's a little too much friction along the path this can occasionally happen. The friction can be caused by fat tips on the filament or strings on unloading.

Part of the solution is to make sure your filament settings are well tuned. So take a look at your tips and see if they're fat or stringy.

You can also make the MMU more tolerant of this by doing the following:
1) Recalibrate the MMU2 bowden length to be about 1cm past the center of the Bondtech gears, and
2) Change the "Loading speed at the start" in the Advanced filament settings to be 19 mm/s (default is 3). The default setting is wrong; 19 mm/s is closer to the speed the MMU2 loads the filament. Fixing this will help keep the MMU from grinding filament as it feeds into the Bondtech.

Re: filament sometimes not making it to nozzle and printing without loading

Thanks for the reply, after looking at my tip, I think I do have some stringing. I forgot to mention I did change the settings on the slic3r filament settings to 19.
I also thought that the filament sensor would know that there was nothing in there and not start.

Re: filament sometimes not making it to nozzle and printing without loading

The filament sensor is not beeing used with the mmu atm. Make sure to have nice tips without strings before starting big prints with lots of color changes. Increasing cooling moves and changing the temperature might help (e.g. 5 °C more or less)

Re: filament sometimes not making it to nozzle and printing without loading

Ok I think it was that thanks