Lulzbot Extruder Hacking

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I was hoping that all my extruder issues were over when I sold the Makerbot (mentioned in my previous post), but unfortunately I am slowly becoming an expert in building and repairing Lulzbot extruders.  The good news is that unlike the Makerbot the Lulzbot is 100% open-source and it is trivial for me to print new parts and make repairs and modifications.

I’ll be glad when I’m done 3D printing parts for a 3D printer and printing other things, but right now I’m knee deep in extruders.

The pic above is all of the extruders for the Lulzbot Taz 4 which I am currently working on.

From left to right:

  • Stock extruder with a modified fan shroud to allow printing in PLA
  • “Fangtooth Guppy” extruder with Hexagon hot-end.
  • Flexystruder for flexible filament

Stock Budascnozzle

The stock hot-end on the Taz for has some issues if you wish to print anything besides ABS.

First off, it leaks!  I’ve had serious issues with filament coming from places that it should not be.  This is a real problem.

I’ve had PLA oozing from the PTFE nut, between the nozzle and the heater block, above the heater block, and even through the setscrew hole for the heat-break! There are a few ways to fix this listed on their website.  I suggest doing all three if you really want it to not leak.  Also make sure you tighten the nozzle and heat-break into the PTFE nut really well, then heat it up to temperature and tighten it up again. Although PLA seems to ooze and leak worse than the other filaments it’s not the only one that has a problem with it;  I’ve had a decent amount of Ninjaflex leaking too.

To get the Lulzbot Taz printing PLA reliably you also need to update the fan shroud to split design like this one or add a second fan dedicated to cooling the extruder fins.  Without this you’ll be able to print smaller things, but will run into issues with the extruder clogging on longer prints.

I’ve only had the Taz 4 for a few weeks and already blew a heater resistor which Lulzbot offered to replace.   It’s a cheap part, but kind of a pain to replace so I am hoping this is not a common issue.

Another thing to note is that the max temperature of 235c won’t allow you to print some more exotic filaments like polycarbonate. Bummer.

Fangtooth Guppy

“Fangtooth Guppy” is the development name for a hotend replacement for the Lulzbot Taz that utilizes a Hexagon all metal hot-end.

The Hexagon hot-end is all metal and has less parts than the Budaschozzle, but requires a dedicated fan for cooling.  I haven’t figured out how I’m going to run a dedicated 12v line from the electronics to power it yet, but it shouldn’t be a terrible ordeal.

I’m excited to print with the Hexagon hotend; It seems like a well designed part.  I’m hoping I don’t have to deal with PLA creeping everywhere this way and maybe I’ll be able to print at temperatures above 235c.

I’m a worried about getting the heater cartridge to work, I bought a few 24v cartridges like it and tried to replace the blown heater resistor in my original Budaschozzle with it, but the cartridge did not maintain temperatures above 120c with the extruder fan on and took so long to heat up that the software calibration routine would timeout.

Flexystruder

My initial build used all PLA parts and as the pictures below show, a combination of the heat from the extruder and springiness of the filament caused severe warping over about 40 hours of printing.

The new Flexystruder with a purple body is printed in ABS.  I haven’t tested the new ABS parts yet.  I expect them to fair better, but after seeing how much stress was placed on the PLA I’m a bit worried.  I kept the PLA gear though, they seem to wear better than ABS and not produce bits of powdered plastic.

So far I have only tried Ninjaflex, but I have some Filaflex on order. Ninjaflex is flexible, but has minimum stretchiness and reminds me more of vinyl than rubber.

Water Schnozzle

All of this extruder hacking inspired me to create a 3D printable, water cooled, heat sink that will work with existing Budasnozzle parts.  I’m hoping I can combine this with a heater cartridge and possibly print at much higher temperatures.  My goal is to be able to print PEEK.

Final Thoughts

The Lulzbot Taz 4 is a very solid machine, but I wouldn’t likely recommend it to anyone as their first 3D printer. In my opinion the current Budaschozzle is really holding it back for less experienced users. The fact that the Taz is touted as the machine to get if you want to be able to print anything is clouded by the fact that it won’t even print PLA reliably without modifications and the hot-end won’t reach temperatures above 235c.

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