Z Top Fix

by pekcitron Sep 25, 2017
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Thank you for post this item. I have just finished upgrading from a mk2 to a mk2.5 and after many attempts to get it to run right I broke the spool holder. I then printed one up and I was checking if I should print any more parts before taking the PET out of the printer when I came across your part. Well when I check my z axis stop ends they were broken so I printed new ones. The rod hole was a little tight but after some sanding I was able to install them.

Thank you very much, I use it on my MK3 clone and it's great! Always preferred this style of Z-Axis tops (open hole).

Just wanted to say thank you!

Thank to you for the thank you :-)

Is the smooth rod portion to be opened after printing? I noticed the model and my print was identical, however, the picture looked like you cut it open. I got them in on my MK2S with a little encouragement, and I'm pretty sure they are not going anywhere. They are definitely formidable in ABS at 30%. I guess if you can get em to fit, leave it be. Thoughts?

No it is not intended to be to cut. The first pic is the older version, I have to redo the same pic as the first one with latest version, just did not have time yet (have to disassemble it)

I noticed you indicated that this goes up to MK2.5 and not MK3. On the forum, you have a link pointing to this one as an MK3 Z top. Could you clarify?. Thanks.

The MK3 fixed the dimensional issue and make it a bit more strong as well, so this project does not really make sense. Thanks for mentioning that, I will add a note to the description

I noticed some misalignment to the threaded z rod regarding to the hole (mk2 kit version)

I talked to the prusa support and they tell me that is ok.
Could be this the effect of the misalignment of the Z top??

Sorry for late answer, I missed your comment. I confirm what Prusa said, that is perfectly fine. The misalignment on z top is in X and in your case it seems to be in Y


I just printed and installed this thing and then noted that lights what i use, are not firmly fitted anymore :(
Big hole on your thing is bigger than hole in stock part.

Could you fix that? (i'm not that good with cad...)

Light holder what i use:

That fits tight to stock part.


Ikea LED holder set for Original Prusa i3 mk2/mk3

That is weird, I have check the SCAD and STL files from MK2 and MK2s and this hole is exactly the same size. It might be due that your print is cleaner than the original one (borders, walls, angles)...

What I can do is adding a little chamfer to the hole for this type of accessories. I will keep you in touch.

Just printed parts to my drone and they do fit snugly.

Also rods to your part did fit good, if my printer or settings was wrong, rods wont fit then also?

What is dimensions for that hole?

My orginal part was about 13.4mm and your part is 13.8mm (measured with my damaged calibers, bettter are lost atm)

The hexagon is made from a circle of 8mm diameter (on mine and on original part), resulting in 13.856mm length. The light holder has a length of 13.30, this is too small to fit correctly. So I don't think your printer is wrong.

Quick tip when printing this type of parts that need to have a tight fit is to calibrate the extruder, good guide here : https://mattshub.com/2017/04/19/extruder-calibration/

When you have angles like inside the hexagon hole, the plastic will take a little shortcut during the print. I suppose that those shortcuts are more important on the original piece, maybe because they are printing faster than us...

Anyway, I have updated the piece by reducing the hole a bit and adding a little chamfer to help fitting pieces that are not perfect. Let me know how it goes :)

Just printed your new version, lamp holder fits better now (without tape :D )



A bit confusing situation.

What i can see, prusa has changed that hexagon size at some moment?

I have done extureder calibration for all my filaments.

Sorry to not be clear, my english is not the very good... Prusa did not changed the hole size. They are printing in specific conditions and certainly faster than us. This makes some differences on angles (but not on flat areas), and thus make some holes like the hexagon could be a bit smaller than the STL file. It is only supposition...

Very happy it now fits better and without tape! :)