Changing filament colors and getting marks
I have been using 2 colors of PLA that I got from Prusa when I ordered my kit. They were white and silver and when I switched them out and allowed the filament to "load" a 2nd time I never had any problem with swapping the colors. This weekend I bought some other other PLA from Microcenter (Inland brand) and I tried swapping between purple and yellow and Im finding marks of the wrong color on my prints. For example I printed some things in purple first and then unloaded it and loaded yellow. I allowed yellow to load a second time to make sure all the purple was out. Then i printed some items and there were several layers that were pure yellow and then I would notice a mark of purple here and there, most of the time it was on the top layer. I looked at my nozzle and I dont see any leftover purple on it. I have now printed 5 items in yellow and still I am getting purple marks randomly on my yellow prints.
Any idea why this is happening and how to fix it? Is it the filament brand? I saw a lot of great reviews on Inland brand and it seems to print really well except for the random color issues.
Re: Changing filament colors and getting marks
Well, I guess its safe to say: happens.
Maybe some filaments are more "messy" in this respect than others, I don't know about Inland, it's not available here. Filament sticks to the inside of the nozzle, gets dragged up further into the hotend when unloading or during prints with lots of retractions, etc.
Sometimes hitting "load" twice is enough to clean the inside of the hotend, sometimes it isn't.
Theres a process called cold pulls (a.k.a. atomic pulls/method) that helps with better removing the previous filament to avoid this issue. It also removes any gunk or debris accumulated in the nozzle so serves as great preventive maintenance. There's even special cleaning filaments for this purpose.
Re: Changing filament colors and getting marks
thanks. I am now wondering if it had to do with the fact that my pulley that was pulling the filament in became loose. I went to switch back to purple and it wouldnt load and I found that the pulley was loose. I tightened that up and loaded purple, loaded again and had no yellow on my 8hr purple print.
I will keep these suggestions in mind for the next time though. Thanks