Z-Axis Fitment issue...

OK so I am in the process of assembling everything. Getting the middle assembly was a little bit rough as my slicer has the problem where holes are too small and didn’t realize it until parts were printed.
Got things reamed out OK and assembled.
Now I am running into a problem when trying to put together the Z-Axis assembly.
The threaded rod is being blocked by the nut and bolt above and below where the Z nut trap would screw in. They are the nuts and bolts for the z-axis bearings

Has anyone else run into this? I am using the newer rigid design for the Z axis.

Perhaps I can grind down the PLA where the bolt goes through, but I’m not sure if that would be enough… I could also print out a spacer maybe to push the rod out, but I imagine that might throw things off a bit.

Any help would be appreciated!



Unless you are using thick headed bolts you should have 3.5mm gap on each of them.

Try loosening the whole middle assembly and see if something was out of wack. I leave everything extremely loose until I am ready to run the machine to make certain things are good and square. Then only slightly snug them down.

I’m using the bolts from your kit so should be good on that front.
I’ll loosen everything up a bit and see if that helps…

The middle section is an amazing piece of engineering.

Thanks for the advice!


Thanks, it took a few tries to get it right. Ive been testing all kinds of things for version 2, starting with the middle. Not easy.

Yeah I bet. What do you think some of the improvements will be for version #2?

Toughest part, choosing what to focus on.
Rigidity, mainly. I would love, less parts easier assembly, smaller footprint, less print time, less expensive, multiple pipe sizes, look better.
I’m still very happy with the first one. No reason to release a second one unless there is something significantly better.

One thing that would be interesting would be combining all of your middle assembly into one huge part. Some of the bigger printers could handle this. Would require supports, but your improved Z does already.

Also, I sorted out my fitment issue I think so hopefully on to the next micro crisis :smiley:



Doesn’t really work that way, I am combing some parts but prints are really only strong in the x and y direction, z is weak. I have a fully assembled version 2 Middle assembly but I think I can do a little better. I will post pictures when I get a little closer to a final part. I really want to be able to handle multiple tube sizes, maintaining 2 versions is not ideal.

Vicious1, it is always helpful to get other ideas and inputs, if only to make that fork in the road, decisions easier!

When you can, post your ideas and photos on the second generation build, and with some construction thoughts
from others, it may make your experience a little less frustrating.

As a forum community lets us try and help you!


I see what you mean. Not to mention it would be really hard to get all the bolts in with one solid middle part as well now that I look at it more.


I have almost finished to print the Z pieces. I printing the IE version of the rigid design and found the same problem explained on the first post. The bolts head are 1mm to far inside and touching the 8mm threaded rods. I missing something? I pretty sure the prints have the correct size.

To solve this problem i planning to cut 2/3 of the head bolts, this way i will have 1 or 2mm of space between the head bolt and the threaded rod.

I can take another look but when I screwed up the first time I had a few people verify the fit before I released it again. It seems to work great for most people, But I will check. Can you tell if the stepper shaft and the z nut lock are in line or is your threaded rod slightly angled? If that is the issue you might be able to use some washers behind the znut lock to line it up.

I had the same problem. Using three washers behind the z-nut lock solved the problem.

When i have the Z axis pieces all put together i will post some photos… For now i still printing the missing pieces, when i have all pieces it will be more easy to check is there are really a problem or not.

And you do not have any problem of misalignment of the 8mm threaded rod? can you post an photo of your solution?

No… My threaded rod turns perpendicular to the table. I’m satisfied with the three washers behind the z nut lock…
Tomorrow I’ll take some pictures of my z middle. Sadly, I don’t have much time to spend working on the mpcnc…

some pictures…