Extruder 1 clicking  

Re: Extruder 1 clicking

Mine does as well. What I have found is that there is a difference when using MMU with a single color, and with multiple colors. When I use more than 1 color, no clicks. With just 1 color, it clicks. There is a difference in the prime cycles between 1 color and multi color.
There is also a difference between a freshly loaded filament, and one that was left loaded from the previous print.
When the printer unloads a filament, it feeds forward first to extrude some, then retracts all the way out.
I think the purge code does not take into account if you don't unload filament between prints. It feeds very fast for the first 50mm of purge to 'load' the hotend.
Here is the purge code from Prusa control: Note:I am not a code expert, and still don't have it all figured out, but have been looking at it.
G21 ; set units to millimeters
G90 ; use absolute coordinates
M83 ; use relative distances for extrusion
G1 Z0.250 F7200.000
G1 X50.0 E80.0 F1000.0 ------- This is the first 50mm of purge, and the 'E' Extruder is feeding 80mm
G1 X160.0 E20.0 F1000.0 ------ Then the next 110mm it is feeding 20mm
G1 Z0.200 F7200.000
G1 X220.0 E13 F1000.0 ---- The the next 80mm, the extruder is feeding 13mm of filament.
G1 X240.0 E0 F1000.0
G1 E-4 F1000.0

I think the issue is in the code, and not with the hardware.
I get the clicking during the beginning of the purge when the filament was already loaded, and it does not last as long if I have just loaded it before the print. I have several brands of the PLA and they all behave the same.
With the multi-material, there are some interesting retraction actions that I am still trying to understand, like after the purge, it pulls back 4mm of filament (E-4), then it does it again (E-4) before moving to the skirt. Then it feeds 4mm and starts printing the skirt, which does not have any filament because it is still short 4mm. So a portion of the skirt is always missing.

I am just starting to mess with the code to see if i can improve the clicking.
My suggestion is to see if it does it at the same points in the process, and what makes a difference.

I should also point out that the MMU works fine and the printer prints great. Just some strange purge behaviors using single color. Also, i have much better success with Control than Slic3r PE MMU, but I wish Control had more 'advanced' features/settings.
Hopes this helps a little.

Re: Extruder 1 clicking

I suggest a careful reading of the Multi-material manual. The way that load filament works now is different than in the past. They are distinguishing between selecting the filament to be used and loading the filament. If the filament is already in the Bowden feeder tube then you don't want to use load filament again. The filament has already been loaded. They don't want you to leave the filament in the extruder after a print run. They want you to unload the filament and confirm that the end of the filament has the correct pointy end. The only time you should use load filament is when you are feeding filament in from outside the extruder. Also note that the process of loading filaments is done in two steps. Step one is getting the filament started into the gears (slow steps) when this has occurred press the knob for the fast feed that takes the filament into the Bowden tube up to just before the point that the feeds merge into the hot end.

My current issue with clicking is that the filament is getting stuck in the short length of tube that sticks down into the hot end. This happens during the print job, the extruder starts clicking because it can no longer move the filament. Then I have to remove the splitter to get at the filament to pull it loose. All in all I'm starting to wish that I had never seen the multi-material upgrade.

Re: Extruder 1 clicking

My current issue with clicking is that the filament is getting stuck in the short length of tube that sticks down into the hot end. This happens during the print job, the extruder starts clicking because it can no longer move the filament. Then I have to remove the splitter to get at the filament to pull it loose. All in all I'm starting to wish that I had never seen the multi-material upgrade.

This is caused by the filament being a bit too hot when it is retracted, so it is still too soft in the metal tube.

Dropping the temperature has fixed this for me, and has been very reliable. Before the MMU I printed PLA at 215/210, now I do 205/200. This has eliminated this clicking, and I also don't need to unload filament between prints (assuming I am using the same color pallet). The clogs upon retraction into the metal tubes are gone.

Of interesting note, I started by just dropping 5 deg, and had fantastic luck with the Hatchbox metallic colors (bronze, copper, silver, gold) and black. Ton of things printed with no issues. Shift to Hatcbhox Red, Yellow, etc and clicking and clogging in the tubes. Dropped another 5 deg (to the 10 listed above) and it works great for all Hatchbox colors.)

Good luck.

Re: Extruder 1 clicking

This is caused by the filament being a bit too hot when it is retracted, so it is still too soft in the metal tube.

Dropping the temperature has fixed this for me, and has been very reliable. Before the MMU I printed PLA at 215/210, now I do 205/200. This has eliminated this clicking, and I also don't need to unload filament between prints (assuming I am using the same color pallet). The clogs upon retraction into the metal tubes are gone.

Of interesting note, I started by just dropping 5 deg, and had fantastic luck with the Hatchbox metallic colors (bronze, copper, silver, gold) and black. Ton of things printed with no issues. Shift to Hatcbhox Red, Yellow, etc and clicking and clogging in the tubes. Dropped another 5 deg (to the 10 listed above) and it works great for all Hatchbox colors.)

Good luck.

Thank you for this tip. Do you just change the default temperatures for the test data sets using tune? I really need to work through all of the posts on this general topic but some things stand out so far:

A) Be sure that the extruder isn't pinching the filament so tight that it deforms into a shape that doesn't slide easily through the MUX assembly IE deep tooth marks. And after you make this adjustment be sure to cut off the filament that has already been deformed remembering to leave a nice pointy tip.

B) Check that the hot end tube isn't so long that the MUX deforms the upper edge and blocks smooth passage of the filament. This was the case with the one installed in the hot end that shipped from the factory. Of course I'm the one that forced the MUX down so hard that the tube deformed while trying to get the screw holes to align.

Also, I would really like to see a setting in the firmware that would allow for automatic retraction of the filament out of the MUX at the end of a print.

Re: Extruder 1 clicking

This is caused by the filament being a bit too hot when it is retracted, so it is still too soft in the metal tube.

Dropping the temperature has fixed this for me, and has been very reliable. Before the MMU I printed PLA at 215/210, now I do 205/200. This has eliminated this clicking, and I also don't need to unload filament between prints (assuming I am using the same color pallet). The clogs upon retraction into the metal tubes are gone.

Of interesting note, I started by just dropping 5 deg, and had fantastic luck with the Hatchbox metallic colors (bronze, copper, silver, gold) and black. Ton of things printed with no issues. Shift to Hatcbhox Red, Yellow, etc and clicking and clogging in the tubes. Dropped another 5 deg (to the 10 listed above) and it works great for all Hatchbox colors.)

Good luck.

Thank you for this tip. Do you just change the default temperatures for the test data sets using tune? I really need to work through all of the posts on this general topic but some things stand out so far:

A) Be sure that the extruder isn't pinching the filament so tight that it deforms into a shape that doesn't slide easily through the MUX assembly IE deep tooth marks. And after you make this adjustment be sure to cut off the filament that has already been deformed remembering to leave a nice pointy tip.

B) Check that the hot end tube isn't so long that the MUX deforms the upper edge and blocks smooth passage of the filament. This was the case with the one installed in the hot end that shipped from the factory. Of course I'm the one that forced the MUX down so hard that the tube deformed while trying to get the screw holes to align.

Also, I would really like to see a setting in the firmware that would allow for automatic retraction of the filament out of the MUX at the end of a print.

0) Whatever program you are using to slice your files (I recommend Slic3r for the MMU - KISS also has a following) you can change the temperatures for the filaments. If you are printing pre-sliced files, you can edit the .gcode (it is a text file) and change the temperature settings. There is one at the beginning, and one after the first layer. You should look for M104 or M109 commands.
A). Yes, the grip should be as loose as possible (just like on the MK2).
B). Yes. The chamfer is also key. Also the length of the PFTE tube between the extruder and the hotend. If it is a bit short, the load function will place the end a bit low, and may interfere with the next filament loading.

The behavior you are looking for is NOT in the firmware, but in the slicer, and is completely under your control. There is customizable gcode at the beginning and end of the print which you can modify to have any behavior you want. It would be very easy to add the unload gcode to the "after print". But to be honest, once you have the machine working well, you don't need to unload the filament in-between. My printer is on its fourth 48hour print in a row, with no unload. Just remove the items, clean the bed, and start it again.