Problem Loading/Unloading and waste tower
Hello all,
I recently upgraded to the MK3s/MMU2s and have unfortunately gotten very few successful prints since I did.
I'm having two issues, which may be related.
1: The printer won't load or unload filament between switching.
- Usually I don't have to fix anything, MMU just stops, I push the button and it will continue to load/unload normally. But it does this every two or three layers.
2: The printer extrudes a glob of plastic onto the waste tower during switching and then on next layer knocks the waste tower off the print bed.
RE: Problem Loading/Unloading and waste tower
If the nozzle is oozing some material, maybe the filament isn't dry enough. Also when changing between materials with different temperatures (ABS-PLA) I'd expect problems - to avoid trouble I currently avoid mixing materials with different temperatures.
Also if the wipe-tower doesn't work (warps or gets knocked off) it's normal to have a lot of issues. I finished two prints without a working wipe-tower, and I had to babysit those prints a lot.
For loading make sure the path is free - sensors calibration is good, printer is built correctly, ...
Here a list of some things that caused me problems:
- after finishing a print sometimes the tip of the filament might not be good
- wet filament
- bending filament
Filament comes from a spool, so it likes to bend - and some filaments like to bend a lot. The placement of the spools, tubes, ... anything can affect the direction of the bend. If it bends too much in the wrong direction it won't load.
I'm still experimenting to find the best setup, ... I tried the original instructions for the setup with the buffer, but I'm not convinced - for me the buffer seems to randomize the direction of the bend. After removing the knife I've had less trouble.
- When the printer shows me any kind of error I usually have to switch it off completely. Most likely there are still some quirks in the firmware. It's sometimes like this: Nothing loads - turn off - turn on - everything just loads without a problem.
Some messages that require me to turn the printer off are:
Anything temperature related - in older firmware there was a good chance to get a preheating error. Now I've seen a "mintemp error" after a finished print (my ambient temperature yesterday was 14°C)
"loading filament 256"
Turning the printer off before starting a new job may avoid some problems.
RE: Problem Loading/Unloading and waste tower
Hello all,
I recently upgraded to the MK3s/MMU2s and have unfortunately gotten very few successful prints since I did.
I'm having two issues, which may be related.
1: The printer won't load or unload filament between switching.
- Usually I don't have to fix anything, MMU just stops, I push the button and it will continue to load/unload normally. But it does this every two or three layers.
2: The printer extrudes a glob of plastic onto the waste tower during switching and then on next layer knocks the waste tower off the print bed.
Your IR sensor may be the issue here. The alignment of the tower and adjustment of the idler door appear to be crucial to a happy MMU. If they are not functioning perfectly loads and unloads will fail due to bad IR readings.
Stringing can also be an issue here too. After an unload failure pull the filament out and see what the tip looks like.
The two things that greatly reduced (effectively eliminated really) (un)load failures for me was to get the IR sensor working perfectly and to remove as much friction as possible between the spool and MMU.
For the IR sensor I disconnected the MMU (from the extruder and the board) and printed as a plain MK3S until I could get through a 20x20x20mm cube with the IR sensor enabled and no false runout errors.
For the filament path I ditched the buffer, put the short (spool side) PTFE tubes in the back of the MMU, and ran off auto-rewind spools (another good way to test the IR sensor without the MMU installed).
Since getting all that sorted I've only had a few tool change failures. 2 were due to having an incorrect tension on the rewinder and the 3rd was because I apparently let the spool get tangled the last time I removed it from the printer.
RE: Problem Loading/Unloading and waste tower
Same problems here. I expected the mmu to be reliable as the MK 3 S, but iti proving to be a pain in the but. The loading and unloading a proving to be disastrous. Sometimes the mmu is spiting the ptfe tubes. the iR sensor is very sensitive. The unscrewing of the FESTO conector can bring him out of whack. Only a successful multimaterial print. it was only with PLA filaments. I have tried tot use soluble supports. but it was no use. the softer filament makes the extruder skip steps. If your ore not keen on printing with different colours I woul not recommended. untillnow every attempt tot use PVA was unsuccsesfull.