Modding the Lulzbot Mini

So recently i’ve finally gotten my homemade / homebuilt Lulzbot mini working. And it’s working pretty good. The most critical problem i was facing was that my 3d printer would start printing either too close to the heat bed (or if i added extra bed leveling washers) it would print too far away. This was a critical problem as the first few layers are the most important and if you can’t get you prints to stick to your print bed then the rest of the print will usually unstick and fail. Thanks to some helpful people on the Lulzbot forum i was able to adjust my z-offset to the correct height that worked for me.

The second issue is that recently i’ve noticed my large and tall prints failing miserably at a certain height and the filament not coming out thick enough and the top gets all cob-weby like a spider web, but worse. Apparently this is called “Heat Creep”. The problem in part may be caused by the tiny blower fan on the Lulzbot mini not providing enough cooling and heat slowly rising in the hot end until the filament actually melts too soon and cannot be extruded properly. This makes sense as the problem only occurs after a long time printing. So the logical step was to replace the tiny blower fan (or squirrel fan) with a larger fan that will do the job. The new Taz 6 has obviously taken that tiny fan into consideration and has changed it to a large 40mm fan.

EDIT: The failing on large prints may be due to me using a half-size stepper instead of a full size stepper motor for the extruder. This means too much voltage is being applied to the motor and it is getting super hot. Over time this means the motor looses steps and probably causes my printing problems.

Unfortunately the Taz 6 x-carriage and modifications are not a drop in replacement for the Lulzbot Mini i decided to make my own. This is what i came up with and it seems to work beautifully. http://www.thingiverse.com/thing:1587110

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I have only tested this on HIPS so far, but it has eliminated the heat creep i was getting with HIPS. PLA apparently suffers more from heat creep problems than other filaments, but this mod will likely help with PLA heat creep issues as well.

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Homebuilt Lulzbot Mini First Prints!

Here are a few photos from my first test prints on my new, now functional (for the most part), DIY Lulzbot Mini that i made myself from scratch (minus the frame and electronics). All hardware assembly and electrical wiring were done by me. Phew. What a ride it’s been. The upside is i now now how this printer works inside and out. The downside it was more trouble that it was worth and i wish i had just bought one instead. lol. Whatever though.

 

Progress on my Homebuilt Lulzbot Mini

Today i made significant progress on building my own Lulzbot Mini 3D printer from scratch. Technically i now have two 3d printers i’m building from scratch, but the other one is bigger and one i’m designing myself. Just like me to not finish one project before starting another. At least i’m going to work on this one and finish it before continuing on my other one (which might be converted into a homemade CNC mill).

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Today was a major milestone because most of the components are put together and i finally was able to test part of the electronics i wired up myself. I was able to test the Y-axis motor and limit switches as well as the X-axis stepper motor. All seemed to function correctly using Lulzbot’s Cura software. The software did have an unexpected safety feature however, it wouldn’t let me turn any of the motors on without the bed thermistor wired up. So i had to wire up a temporary 10k thermistor for testing purposes. It worked great. I was running the Cura software under Ubuntu Linux. The Cura software gave me an error that it could not autodetect the serial port or something like that, so i ran it as the root super user and that fixed the problems.

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Since i’m building this thing from scratch instead of buying one premade i’m trying to find ways of cutting costs. Although i think i will end up spending more than i hoped. But anyway, part of that is looking into ways that i might be able to replace expensive commercial products like the IGUS bearings and the Leadscrew nut. I’ve already drafted up a 3d printable version of the leadscrew nut and posted it here on Thingiverse. The nut has yet to be tested, but i’ve also had some RJM-01-08 IGUS bearing replica prototypes made in Nylon. The RJM-01-08 IGUS replica bearings turned out to be too tight, but with a drill i was able to make them usable. They are currently being used to remove the wiggle and slop i was experiencing from using the 1mm too small LM8UU ball bearings.

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I originally got the LM8UU bearings as a cheaper alternative to the commercial RJM-01-08 IGUS stock bearings the Lulzbot mini uses thinking they would work. They work, and i am currently using some, but the stock STL files from Lulzbot have holes that are 1mm too big because of the slight size difference between them and the LM8UU. I might try to modify the STL files [i have modified the lulzbot solidworks files] to make LM8UU compatible parts in the near future, but for now i’m happy with my 3d printed nylon ones. I’ve heard PLA might work too, so i will experiment with that in the future as well.

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Here are some more pictures:

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Project Updates November 2015

80/20 1020 Extruded aluminum t-slot y-axis 3d printer bracket
80/20 1020 Extruded aluminum t-slot y-axis 3d printer bracket

The first update is that i’m still steadily designing new parts in solidworks for my custom 3D printer. This photo is one of two y-brackets that will hold the 1020 size t-slot extruded aluminum (from 80/20) y-axis beam. It looked good in Solidworks, now it just needs to be fabricated (3d printed) into a real-world working part (as with many other parts).

Y-bracket for custom 3D printer
Y-axis bracket for custom 3D printer

It’s really fun designing parts and then seeing them become real functional parts. Recently I’ve even been looking into a local program for CNC machinist training as a job. Apparently there is a large shortage of qualified CNC machinists in my area along with a booming and returning engineering and manufacturing hub here in the area.

While i was designing new parts and fitting them together i found a few minor problems with a few of my old designs being off and not lining up properly with the 1020 extruded aluminum. So i spent some time fixing that and cleaning them up a bit. Good to find those errors on the computer first than after i make the parts.

I received the prototype PCB’s for the XYZZY Motor Controller 1.0, The downside is I’ve found numerous errors that i missed, so I’ve been trying to fix those. But then to compound those problems the main circuit itself has a problem where the HIP4081A h-bridge chip circuit is only driving a motor (in this case a test load LED) in one direction. At first it was shorting out the other direction, but now i think it just loads the current down and does not activate one side of the hbridge. It’s actually driving me crazy trying to fix it and find the cause of the problem, but it’s still quite a mystery. Perhaps electronics is just not my thing. Perhaps i really should give up on that project after never being able to have good success. But i don’t know.

In plant breeding news: i was able to harvest three corn cobs this year. Two were decent sized purple husked corn cobs, the other was a good multi-colored flint. The third one had lots of kernel color diversity, it even had several speckled kernels, and chin-marked ones, and even some that had both speckles and stripes! I recently found purple sweet potatoes at Whole Foods and i will be trying to sprout one and grow my own slips for next year.

I was also able to grow a few good squash this year, some good progress on the pea breeding, and an excellent year with Joseph’s Watermelon Landrace. Sorry, i didn’t get good photo’s of the watermelons, but i had some excellent red sweet watermelons and some good yellows as well. Especially for Northern Colorado, the watermelons are the plant breeding project i’m most excited about and ironically having the best success. Can’t wait for next year! And all this despite it being an incredible difficult and strange gardening year!

DIY 3D Printer progress piece by piece

One of my newly resurrected projects is my ambition to deign and build my own functional 3d printer. Eventually i’d love to just purchase a nice one, but i’d also like to build my own (besides i already have most of the parts and mine would be bigger too). The pre-made model i would buy is the Lulzbot mini. Mainly because they are fantastically built machines, but also because they are produced by a company here in my own town! Plus they have a philosophical commitment to open source which i love.

Anyway, building off of my original post in 2011, I’m designing from scratch a 2ft x 2ft 3d printer. I’ve been steadily making good progress piece by piece, step by step. My main design criteria are: as close to a 2ft x 2ft build area as possible (maximizing build area vs machine footprint), using 1″ 10 series 80/20 t-slot extruded aluminum, minimizing unneeded parts by using t-slot linear bearings (real aluminum ones and 3d printed working replicas), and trying to just have a simple design by default. I’ve had fun these last few weeks by printing out working 80/20 linear bearing CAD models into working plastic prototypes. My next step is to print out some motor mounts. I’ve designed two motor mounts so far. The first one is a snug mount that shapely fits around a motor and has built in t-slot mounts intended for the z axis lead screws. The second is a simple right angle slotted mount for y-axis that has a belt drive. I have them modeled in Solidworks 2007. I just need to print them out to see if they will work.

motor mount 1

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3d printed linear bearing (80/20 t-slot)
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Initial frame of diy 3d printer with 3d printed linear bearings in view (80/20 t-slot)

Updating and perfecting the XYZZY Motor Controller

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I’m working on finishing and perfecting an old project of mine (by a few years). The XYZZY Motor Controller (H-bridge). The old design was only somewhat functional. Enough to prove proof of concept (barely), but i want a sleek, finished version that people can actually use. So i’m working on perfecting this prototype design. I’ve just updated several things on the top board, and i think it’s done. The biggest issue was a pretty major design flaw which was that i forgot to add the safety diodes for motor kickback. In simple terms that meant that when the motor stopped turning or i switched it from forward to backward the electrical energy would destroy the Mosfets! …oh.. noo… Yup.

Not to worry, they are there now. I will be wiring them in manually to some of my old prototype boards to test soon. This design is progressed enough to update it to V1.0 instead of Rx.x number. Although the top board is finished, the bottom board needs quite a bit of work and possibly major redesigning. from the looks of my old design for the bottom board it looks like one feature i wanted to implement was an I2C bus. That would make it cool to connect them together and then to a microprocessor to monitor them in real-time. The only sensors to monitor at this point was the inclusion of a crude temp sensor and monitoring the RPM of the fan. Although i was hoping to build an arduino chip built in. When i eventually purchase new PCB’s i think this revision is finally deserving for the color red! Although purple or black would look pretty sick too. Any comments are welcome.

This is an Open Source Hardware Design.

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