Homebuilt Lulzbot Mini

I’ve started on a project to build my own Lulzbot Mini from the ground up. So far things are going well. I’m starting to put things together slowly piece by piece. I’ve got most of the critical parts tracked down and just needing to locate a few more. One question is if there is a way to purchase those ferrite toroid jumper things for inside the electrical panel. I suppose i can just buy the connectors from digikey or something and make my own, but i was just curious as Aleph Objects seem to have only a limited amount of spare or replacement parts available on their website.

The second and more critical question i had is concerning the heated brass inserts. I’ve been using the build guide from https://ohai.lulzbot.com/group/mini/, and it’s been helpful, but there are a limited amount of photos available for viewing where all the brass inserts need to go. Some of them i can see clearly, and others I’ve just been guessing as i go along. If anyone has more clear photos of those that would really help me out. Thanks.

Neat! That’s gonna be a big mini

Also, as i was putting in some brass inserts today i stumbled upon a part that has slightly odd CAD dimensions. You can see from these photos that this piece has one set of brass inserts right next to the edge which creates a small melted blemish when inserting the hot brass, while the other side clearly has another millimeter or two of clearance. I’m not sure if that was done on purpose for some reason or if it was just overlooked in the CAD file. Not a big deal as it should work fine, but it was a little weird.

Great looking build so far Biolumo. I will be watching this thread for sure. Where abouts did you get the heat set inserts?

Thanks, i’m hoping it all turns out well. I’m all for an adventure building something, but part of me can certainly see the benefit to purchasing one instead lol.

I got the inserts from McMaster Carr:




Cheers, thanks. I was hoping it wasn’t MCm. It seems tough to bring them into Canada.

Well, this was the first time I’ve ordered from them. I’m sure there are alternative places you could find them. Especially in a metric country like Canada. The Lulzbot mini BOM says that Aleph Objects does not order theirs from MCm, but instead from Fastenal. I’m not sure how easy it would be to place an order with them from Canada.


I will check them out. Due to my location it is typically a lot easier for me to order online than it is to drive and pickup

You can also get the inserts here.


Looks great so far - I’m also toying with the idea of building my own. Did you get the frame fabricated from the shop drawings or did you order one through Lulzbot? Any tips on the frame?

As far as the brass inserts go, I’d just put one in whenever you’re screwing something in.

Here they are http://i-t-w.com/parts/?category=Mini

Good question. The frame is probably the most important part and/or the hardest part to obtain. I went the easy route and got mine from Jamie @ IT-Works. The frame itself probably could be fabricated, but i honestly don’t think it would be worth the effort. Plus it has several threaded inserts that would make it difficult (although perhaps they could be replaced with nuts instead). I do wonder if the frame could be replaced with t-slot or something else. The Lulzbot mini is missing several freecad files on their website. STL files are provided for all, but not the freecad files. In particular the frame has no files available except Solidworks. For those interested i uploaded those Solidworks files for the frame onto 3dcontentcentral.com which can be freely downloaded in a variety of formats (including IGES and STEP files).

And yeah, i think I’ve figured out where more of the inserts go, it’s mostly common sense things. If i miss one i can always go back and add it later. Hopefully more photos to come as i build more.

Does anyone know how the limit switches are supposed to be wired? Normally closed and common? Or the opposite?

From the pictures it appears to be normally open and common which is what is logically what makes sense. Unless i hear otherwise i will assume that is what it is.

Normally open. You can see the plug headers in the ohai kit documentation.

Dang! I used to be able to find a great deal on the threaded inserts at Fastenal (we have a company discount there), but it appears the metric ones have all disappeared from their web site (either that, or I’m not searching correctly).

Okay, i’m making progress one step at a time. Today i was able to get the Y-axis limit switches wired. I have most of the motors wired to their connectors. I was able to test the X-axis and Y-axis motors as well as the Y-axis limit switches. So far everything seems to function correctly. The lulzbot cura software would not engage the motors without the bed thermistor attached, so i wired up a temporary 10k thermistor for testing purposes only. It did the trick for me to test the motors. Perhaps in the near future i can take some more photos and perhaps a quick video, but not too much to show at this point yet.

Here are a few updated pictures.

oh, i forgot to post a picture of my little thermistor bypass thingy. Simple, but effective.

And here is a photo of some prototype RJM-01-08 IGUS replica bearings 3d printed in Nylon next to some LM8UU bearings:

Today i had an unexpected problem. When using the cura interface i pressed the “home y button” and the bed plate moved the opposite direction. On top of that the y-max limit switch did not stop it. Fortunatley my belt was not tight, so nothing broke, but it was not cool. :frowning:

  1. Why did it do that? (and yes i have the limit switches in the right place and plugged into the correct ports, they seem to function fine manually when the belt is not hooked up. The motor just goes the wrong way).
  2. Will reflashing the rambo mini firmware fix that? And if so, how do i do that?
  3. While i had read that the software does not check or respond to the opposite limit switch, why not?? Programming the software to respond to either limit switch should not change behavior and would add extra safety measures.

You probably have the belt routed upside down from how it should be. This picture may help: