A Very Minor Disassembly on Your Tool Head

Our Library District recently purchased a Lulzbot Mini 2. I started working with it in March and just recently got it back from a branch. It seems to have survived its first adventure!

I am still learning about the Mini 2, which really needs a name, and trying to use up old filament printing some components for maker programs.  I started printing some examples for an upcoming Repair Cafe at one of our branches to demonstrate something useful made with the printer.  I found this watch band that I think would be awesome as I currently have a watch without a band! And, of course, why not use super glittery Proto-Pasta filament?  The watch band actually printed out pretty smoothly, but the links fused together at the bottom and I snapped it apart. 😒

But! Before I could try again, the filament got jammed into the Mini 2 tool head... again!  This has now happened every time I take the printer out to print something.  I followed all the steps that helped me release the filament from the tool head the last few times this happened, but this time the filament just snapped off right at the idler...

I have been eyeing the screws on the side of the fan, thinking, I could take this apart. I could probably get that filament out of there and maybe put all this back together...

But the printer is new, so I sent an email to Lulzbot with a picture asking for their advice. Their reply:

I'm sorry to hear that you are experiencing this issue with your tool head. In this case, I would recommend doing a very minor disassembly on your tool head to try and get the filament out of the tool head. To do that, you can follow the steps on this link here: https://ohai.lulzbot.com/project/mini-2-aerostruder-hotend-replacement/maintenance-repairs/

Greenlight to tinker! Whoooo!

I found this video from IT-Works 3D extremely helpful during my adventure:

I may have watched it...a lot.

The process of getting the tool head dismantled was relatively simple. It only takes one hex key, and Lulzbot sent me a set with the printer! The trickiest part was getting all the wires disconnected.  Then the thing basically exploded apart...easy...

When I got to the filament, I had a nice long strand to grip and pull...and it snapped off at the top of the hot end. FML.

So, how do I get the last little bit of filament out of the hot end...? I've used a hair dryer to heat up PLA before.  What did Program Services have that I could use to heat up the filament and/or metal to get the filament soft enough to pull out? I found a metal pointy stick and got some very hot water. I slowly, meticulously, started poking at the leftover filament to get it malleable enough to grab and pull out with the pointy end. This was not going well...

Then I turned around and saw a bunch of soldering irons still sitting at my desk from Outreach in April...

The soldering iron worked great...almost too good. It sort of liquified the PLA (gotta love that burning plastic smell) and I was able to scrape it all out. Yay! Mission Accomplished!

I re-assembled the tool head, only having a minor hiccup when I couldn't figure out how to run the wires so it wouldn't get tangled in anything...and remembering to plug the heater block back in.

I was super amazed that the printer turned on when it was all re-assembled!

But then the printer started making a terrible hissing sound and filament wouldn't load! I think the hissing sound was just leftover remnants of a filament burning off, but without new filament to push out whatever was left of the old filament, I couldn't do much about it. So, I stopped working on it for the day and decided to take a fresh look at it the next day.

I was hoping when I came in the next day, I'd get things wiggled around enough to get the filament to load into the hot end, but no such luck. So, I took the tool head apart again to get the filament guide set correctly. And this is when the real nightmare began!

The filament guide is a loose piece of a plastic tube that sits just below where the hob gear and idler meet. It guides the filament so it runs right into the hot end. Cool, cool cool. The 1.75 tool head apparently has a nice rigid guide that you can put in the hot end, the filament guide, and up through the idler so everything stays aligned when you reassemble it. Not so for the 3mm tool head on the Lulzbot Mini. 😭  It is an intricate dance of keeping the filament guide in place while keeping the hob gear and idler aligned and shoving the heat block in place.

Ultimately, I got everything lined up with filament fed into all the pieces, used the screws to keep everything in place while I removed the filament, then plopped on the heat block and screwed it all back together. This really doesn't do justice to the 3 hours I fiddled to get everything lined up at the same time. 😂

I found this really cool document of the complete build of an E3 Titan Aero tool head. Apparently, building one from scratch only takes ~1 hour. Troubleshooting one took me ~8 hours. But I'm getting faster! If we have issues with the Version1, I feel very confident in tearing it apart!

Right now I'm printing an EEZYbotARM as a demo for our summer reading program (we'll be making robotic arms from cardboard based on this model) and some SMARS robots as a future Arduino program.

Also, we named the Mini2: 2Legit2Print