Lulzbot Clogged Dual Extruder

General Hardware
1

Hi All!

Long story short, I started a test print with some new PLA filament and left it overnight to run. When I came back in the next day, one of the extruders on my Lulzbot Taz Pro Dual Extruder Toolhead had baked filament encasing

I wasn’t able to remove all the baked filament from the hot end extruder , as unfortunately it encases the entire extruder. Please see images below:
1016 & 1017 images are the clogged extruder from which I removed from the tool head. You can see not only does it encase the entire extruder, but the leveling board as well. 1018 shows the current status of the dual extruder tool head, which I was able to put back on the tool head plate, and successfully loaded filament through the 1st extruder which had no filament use, and was completely functional.

IMG_1017
IMG_10173024×4032 2.63 MB

The attached video file 1019 shows what happens when I try and run a print from a USB. The printer starts to shake when the toolhead reaches the top of the Y axis, as if it something wrong with the Y axis calibration. If I manually pull the toolhead down, the printer is able to bring the toolhead back to the top of the Y axis pulley, indicating there is nothing physically wrong with being able to move up and down the Y axis. Once it starts to shake, the printer itself just restarts.

Let me know your thoughts and if there is any suggestions you may have. Ive already reached out to lulzbot to order a new dual extruder, since removing the clogged extruder does anyone think it is possible to print using the loadable extruder without interfering without running into calibration issues?

Note this is the dual extruder from the original shipped printer, not the new v3 tool head.

Thanks,

Starr Kramer, Victor
Visualization Technology Specialist
Contractor, Medical Science and Computing, Inc.
Bioinformatics and Computational Biosciences Branch (BCBB)
NIH/NIAID/OD/OSMO/OCICB
Phone Cell: 202-748-2878

2

I just see the one image … no other images or video.

My guess is you probably wont be able to separate that filament from the extruder without also damaging the blower shroud. BUT… you can print a new blower shroud. That part can be found here:

http://devel.lulzbot.com/TAZ/quiver/production_parts/printed_parts/blower_shroud/

You will also need some heat-inserts. You can find the documentation on which sizes and where they are installed in section 5 of this page:

https://ohai.lulzbot.com/project/thermal-insert-instructions/quiver/

Thermal (heat) inserts require a soldering iron to insert. Basically you heat them up and push them in. You can buy heat-inserts from lots of sources. I usually get mine from McMaster-Carr (online). You can search their website for “heat-set inserts”.

LulzBot might be able to sell you a replacement blower-shroud with all the heat-inserts installed … but I didn’t see them on their “parts” page (but it’s probably worth a phone call).

You can likely use a soldering iron to slice away the blob of plastic to free the extruder. The tricky bit is… can you do it without damaging the wires to the heater-cartridge and thermistor? If not… you may end up needing to order a new heat-cartridge and thermistor for the extruder (those will be fairly cheap).

Meanwhile that Y axis… can you describe this a bit more?

Does the printer reach the limit of travel on the Y-axis and try to keep moving (so you hear the motors fighting even though the bed can’t move anymore?

If yes … then check the bump-sense setting on the printer.

On the printer control panel, touch “Menu” -> “Advanced Settings” -> “Bump Sense” and read the values. On my TAZ Pro the bump-sense is set to a value of 5 for the Y-axis (and 6 for the X-axis).

The printer does not have mechanical end-stop switches on X or Y … it uses a feature called “Bump Sense” … it’s a feature of the Archim control board. It is able to determine how much amperage is being drawn by the motors when running the motors. When motors meet resistance, they draw more power to try to overcome the resistance. The control board can sense this and… realize that it’s hit the limit and stop.

See: https://marlinfw.org/docs/gcode/M914.html

Increasing the value makes it more sensitive to resistance. HOWEVER… if set too high then a false-positive can be triggered. That can result in issues such as layer-shifting on that axis. Setting the value too low can make it fail to sense the travel limit.

Inspect your Y-axis belt … make sure nothing got stuck in the belt that might have caused binding.