My Project Mini [Fixing -> Restoring -> Farm]

I was really lucky to buy a Mini from another member here who had it for parts. I already had a Mini 1.04 and it’s been a great solid printer. I print for fun, but also print some parts that are used in production. With a tight budget I started looking for another printer to fill the production need. The Lulzbot printers were way out of range at the moment, so I was looking for “cheap” printers before this opportunity came up. Now I can run the same gcode on both!

The background on the printer was it was not working, there were issues with the extrusion and the previous owner had purchased a new Z axis and Extruder harness from Lulzbot. There were are a few parts and bolt missing, nothing that couldn’t be replaced. I also knew the Mini was in the 1.03 range of printers so I also wanted to get it up to the 1.04 to match my current printer. I made an assumption that the rambo board needed to get upgraded becuase the 1.04 uses a different board and it may be why the extruder wasn’t working since the harness is new. So I ordered a Rambo Mini as well before the printer had arrived. To my surprise, they both arrived on the same day. I also wasn’t worried about the printer not having an extruder since I had a second one.

Now I got excited and started working on it right away so I am missing some pics, but I’m not done so I’ll try to be better at that.

The front idler was broken so I replaced that with a 1.04 idler in Chroma Strands Lulzbot green. This was also so I could visually tell the two printers apart. I also added a stepper damper to the rear motor

Next step was to install the new board, I’m missing a few a pics here. I unplugged everything, replaced it and went to work. I followed the z and extruder harness and decided to take it all apart to tie down the harness like in the production notes. On thing I noticed the ferrites were different on this printer than my 1.04. On the 4 the ferrite it integrated into the harness. Seeing that the new harness had one I tore out the individual old ones and added one from the parts jar to the lowers. Here’s what I ended up with.

I added the extruder, I had also printed a new top wire cover and fan duct in green so I can tell it apart. This head will eventually have a .8 nozzle. I’ll have black for .5 and grey for .25. I also made a modified spool arm for 5lb spools. It uses some 2020 for the body so that the height can be adjusted. Finally the printer was ready to test and see how it works.

I got positioned the printer in it’s new home and loaded up a reel of IC3D Grey ABS. I like printing with ABS because I’ve never had good success with PLA. I know it’s said that ABS is hard to print, but for me it’s been less finicky than PLA as long as the first layer is good. I’m having better luck though after switching to Titan Aero heads instead of the 1.04 hexagon head.

Anyway, the extruded warms up just fine. I load filament and extrude a few MM to get it going. Then load up a rocktopus and begin to print. Almost right away I get a thermal run away error. I reset and try again. Same thing, so I figured it was the bed this time since the extruded worked great, and everything else moves and homes correctly. Time to take it apart again.

This time I decided to rip out the entire bed heater harness and started doing continuity tests. There it was, one of the bed heating wires was bad and the bed was not heating. At this point I noticed the harness was different than the 4 as well. The cable drag chain was wider than the 3 and the wires were pretty bunched up which was part of the reason for the wire failing. It was also 14ga and very stiff wire. After looking over the wire harness documentation and BOM of the 4 I saw they switched from 14ga to 16ga wire. I got the wider cable drag chain from McMaster and some super flexible silicone wire from Amazon.

While I’m waiting for parts I notice the bed that came with it needed a new PEI sheet. Since I had upgraded to the modular bed on my 4 I pulled the original bed out and installed that. One of the things I do not like about the 3 is the bed mounting plate compared to the 4. The bed corners make it more difficult to center the bed and the spacers for the leveling disks are dinky in comparison. I’m working on sourcing an updated bed from Lulzbot if possible. In the mean time I printed some new bed corners with Cheetah TPU in hopes it will help centering.

Time for surgery. It was pretty straight forward, I transferred everything over to the new drag chain and made sure everything worked. So now it was time to try to the roctopus again.

Before the roctopus, I found the burn in gcode and ran that just to see if everything was working correctly. Fun fact, that gcode doesn’t warm up the bed, so I still didn’t know if it fixed the problem. I did notice that the 3 is a lot louder than the 4. I think it’s mostly because of the Z axis motors not being Moons and lacking a dampener. I think that’s next. So now I loaded the code for the roctopus and and it went off without a hitch. I printed for speed and not detail because I just wanted to make sure it all worked. Success!

Update 2

Update 3


… you can’t just leave us in suspense. Tell us it works!

Sounds awesome.

Sorry, fatherly duties called and I had to stop. I just added some more!

Update 2

Now that I have the printer working I decided to check the fine settings and see how it does. I used some Protopasta HTPLA to print some toys for my son.

First was something from the Lulzbot samples. It printed out great using the factory settings.

Next I printed a Super Mario figure. This was on high speed settings, but about a 3rd of the way up I had some Z hop. During homing, I can hear a high pitched sound, so there may be some biding on the Z axis. It’s not a lot since it moves freely and the steppers sound smooth.

Since the 3 doesn’t have any stepper dampeners on the Z axis, I wanted to add some to quiet the machine down a bit. On the 4 the lower mounts are different to accommodate the MOONS steppers and dampeners.

I also noticed when I was checking the wire harness for the z/x axis that the 4 has x-end mounts that help with wiring and strain relief. So I decided to print these parts from the 4 and a few others to continued to update the 3.

Update 3

I installed the new belt clamps, at the most extreme ends of the axis there was some rubbing on the belts and these seem to have fixed that.

While I was taking things apart, I adjusted the Z axis and I printed another Mario. It seems like Z hope problem I had was taken care of. I also noticed the bushings were pretty worn out on the X axis and needed to be replaced, same goes for the Y but those were in better shape. Since the ones that come stock are pretty expensive, I decided to try some LM8UU bushings, but those are a bit smaller in diameter. I decided to redraw the all the parts that use bushings to accommodate the LM8UU, and printed the bed ones first. Fingers crossed they work!

Also, can I just say how awesome cleaning filament is?

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Awesome thread Iggy!

Do you have a spec on the ferrite that is used on the 1.04? I am getting ready to replace the mini rambo board on my mini. The wiring looks to be a nightmare on my 1.03 with the 4 ferrites. Will any ferrite work? Do you think I could use 2 of the existing ferrites to run the wires through like the 1.04? Probably a split one would be better if I ever need to change another bed harness. I assume they use the ferrites to reduce electrical interference coming from the printer? I guess that is one of the things that make the Lulzbot more expensive. Probably don’t find them on a Creality.

Also on the bushings: I just ordered some from Igus - I hope I got the correct ones. They are not cheap. They appear to come in a Japanese size and standard size. The RJMP-01-08 has an O.D. of 16mm. The RJ4JP-10-08 (Japanese) has an O.D. of 15mm. I also noted a similar thing when I looked at LM8UU metal linear bearings. The ones from McMaster were 16mm and the cheap ones from Aliexpress were 15mm.


Until I found one in the parts bin, I used two of the ones it came with. These look like the ones I’m using.

Thanks Iggy. Placed my order.


Update 4

I had been developing the parts to to use the cheaper IGUS bushings. I had made my the bed ones too tight and I was having issues with the resistance on the travel, so I was tweaking the diameters to make them work and I think I got it dialed in. On the Z axis I used the OE spec bushings because I had already printed the parts, but I worked the files for those too.

Here’s the result of the updated printed parts with heat inserts installed. The hardest ones were the 2mm located towards the center of mount.

This is the starting point for everything. You’ll noticed I have a new print bed plate too. I’m very lucky to have scored one of these from an unnamed source.

The empty frame! It’s so light. I had added an LCD as well but I forgot to document this because it was giving me some issues. More on that later. Tearing the whole thing apart is pretty straight forward.

Mini 1.03 X and Z axis with a previously updated harness. Time to take this all apart too.

Another shot of the Igus Drylin RJ4JP-01-08 LM8UU bearings for the extruder carriage.

These were hard to source! I couldn’t find them in all black like the OE ones, but they are the same spec. I accidentally got 3 and only needed 2. I didn’t notice the back motor on the Y axis was already a MOONS.

And this is how far I got today. I could not get the damn couplers off! I’m almost there in terms of putting it all back together, but will have to wait for new couplers.

Here’s a closeup of what caused a lot of cursing. There is a ton of what I can only assume is thread locker. After heating, scraping with a tiny pick and acetone, I managed to strip out every screw I tried to remove. I’ll be drilling them out tomorrow when new ones arrive from McMaster.


  • Finish rebuilding the mini X and Z axis.
  • Wire up new bed and make sure all bearings move smoothly
  • Once assembled run burn-in gcode
  • Print Benchy


  • Adapt a flex plate bed
  • BLTouch (doubt full because of Mini Rambo)
  • Convert Aerostuder to new style extruder to fit with adapter plate.


Well, I tried to drill the set screws out and had a hell of time getting them free. So sometimes you have to have to perform surgery with a shotgun. I took my grinder with a cutoff wheel and carefully cut through the coupler.

Yay! It’s free.

Today I finally got the coupler I needed, the correct one I should say, from ITworks. I had ordered some couplers from McMaster, but they were shorter and they didn’t have anyway to secure the slot on the on the shafts. I was able to get the Z axis assembled and ready to go.

Here’s how far I got today. Z axis is assembled and leveled. The stock lower strain relief didn’t fit so I had to print a new one. I’ll be waiting for that to finish the rest of the assembly and do some test prints. Cant wait to work on the next project in the big box in the background. :wink:

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