Can my MMU2S cut filament instead of unload it?
I got MMU2S a few days ago.
I have been trying to print multiple color objects but I realize that many failures occur when the filaments make be unloaded.
So I came up with a solution to avoid failure that cutting filament instead of unloading.
But I could not find the settings that related to my solution. How do I make settings for that?
RE: Can my MMU2S cut filament instead of unload it?
You want to cut every filament? That doesn't sound like a good solution. The filament gets cut when it is up near the selector, so it still needs to be unloaded first. Additionally, this results in a straight cut where as a properly unloaded filament is pointy. I've found that a straight cut filament gets caught on the PC4-M6 fitting at the top of the extruder FAR more often (approaching 100% in my case, I may need to replace the PTFE tubing) than a pointy filament.
I think cutting the filament on every filament swap, while it seems like a good idea on the surface, is going down the wrong path. I think you're trading one problem for another. Especially when you consider that some prints have thousands of filament changes, you'd end up with thousands of tips sitting in the MMU selector.
Instead of going down that path, I suggest that you start looking into filament tip tuning. When the MMU tries to unload a filament, it'll pull it out a bit to cool it off, then shove it back in to the hot part to soften it up. It'll do this a few times, and if done properly, it will result in a perfectly straight piece of filament with a pointy tip. Improper tuning will result in a bulb, or sometimes even a hook, at the end of the filament that can be too large to be pulled through the PTFE tubing or the hook can get caught on something while it is trying to back out.
It can also create a long, thin stringy tip. These long and thin strings occasionally get broken off at the MMU selector and create a birds nest that sits underneath the FINDA sensor causing a false positive. It can also create a ball of filament that gets caught on the end of another filament as it is being loaded. This ball can cause the overall size of the filament to be just a tad bit too large to enter into the extruder, causing a failure to load.
So, armed with the above knowledge, you can try making a post in the MMU2S forum. Provide any modifications you made to the MMU while assembling it. Provide pictures of tips that you're getting on a filament swaps. Provide the plastic type and manufacturer of the plastic. I've had terrible, so very terrible, experience with white Hatchbox PLA. Other colors and brands work perfectly fine. A three day print turned into almost 7 days because of the stringy tips causing a jam every 3 or 4 filament changes.
RE: Can my MMU2S cut filament instead of unload it?
I had to spend a lot of time replying because there were problems.
As your advice, I tried the other filaments like Prusament PETG/PLA, and so on then, I saw the printed objects and their quality. I faced the temperature setting problem like getting bubbled surface for Prusament PETG on 240 °C but I can get a good result at 215°C with the same spool. It is so weird because Prusament PETG has to be good on 250°C. And it is not solved yet.
So I also required Prusa support and the current solution is the motherboard replacement that is not in my place yet though.
Anyway, thank you for your advice. It was helpful to examine my printers.