I am going to try to make mine work with Mendel Max ACME threaded rods and nuts. It seems like the Z-nut spring is the only part that will need modification. When I get it working, I will put it on Thingiverse.

I had initially modeled it in FreeCAD when the TK-0 was to have 3/8-12 leadscrews. They since changed it to M6 threaded rods and the revised fcstd file is not available. I don’t know if there were more changes.

I could always export my model to STEP and attach it if it will help (IMHO it’s a lot better than an STL). I don’t think the Lulzbot guys use SolidWorks anymore… At least they’re trying not to since they are strongly committed to using open source tools. Even if it’s slightly more of a hassle sometimes.

Edit: silly me. You can download the STEP file from my now outdated Github repo. https://github.com/normandc/Lulzbot-TK-0/tree/master/STEP

Thanks. I have it in Solidworks now, and am working on it.

I am going to have to move the center of the rod 5mm away from the mount point. So I think that means I will also have to adjust the Z motor mounts by 5mm, though I have not looked at that yet.

Either that or I will have to mill 5mm off the Delrin nuts, but I think that is a worse solution.

Is it actually important that this act like a spring rather than make it solid?

This is my first draft. I think it will probably work. If anyone wants to try it before I get my printer going, I can send the file. I also finished with the motor mount mod.


if you are using very straight acme rods…probably not. I would certainly thicken up those ribs a little bit (1.5mm at least).
What are the dimensions of the nut? maybe you can mill a flat on one side so you do not need to move the motor in as much.

fyi, this forum area is dedicated to the stock taz…the mods may move this to the development area.

I made it thicker. Also I did a rigid version. I don’t like how the spring also flexes in the Z axis - that will make layer thickness variable. The ACME screw should not have significant wobble, so I am not sure that a spring is needed at all. There are now larger motor-mount screw holes (requires washers) so that the final motor position is adjustable.

Looking good!

Out of curiosity, are the Delring bushing themselves threaded, or do they have threaded metal inserts? Sorry, I know nothing about mechanical systems.

They are ACME threaded in plastic, with a very tight fit. There is no chance of backlash.

I know little about this printer so far, but when I install them, I may decide to recess the nuts into the mounts.


I updated the model. It is compatible with the standard motor mount now:

did you offset it in Y by 0.75mm?

for some reason the X bearing for spring/motor have the mounting holes for the Z nut 0.75mm off from the center of the mounting holes for the Z bearing holder, and therefore motor mount (at least the original files do). Not sure why that is or if something else is off in my assembly.

maybe the double bearing holder is not symmetric ?


Were there any adjustments to the software to compensate for the difference in screw nut size? Or is this modification a “drop-in” replacement?

Great job on the CAD work, the parts printed cleanly. I’m waiting for them to restock the Lead Screws (they were sold out) :frowning:

Has anyone been using these? I’m thinking about going this route on my build.