Prusa i3 Z-axis reinforcement

by Shii, published

Prusa i3 Z-axis reinforcement by Shii Jul 3, 2016


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Z-axis reinforcement for Prusa i3 MK2
Reinforces Z-axis and helps removing Z-axis wobble for better print quality

2x M8 430mm threaded rods, front Y axes replacement
2x M8 440mm threaded rods, Y to Z axis connection
16x M8 nut
16x M8 washer
4x M3 25mm screw
4x M3 nut (preferably nylon insert locking nuts)

Based on design by cylgom

Print Settings


Prusa i3 MK2









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How wide printer is after this update? ~450mm? Thanks!

it is 430mm, same as front rods.
Edit: actually, scratch that. Its not any wider. x motor and power cable plug are still going further then front rod.

Could you make please edit the top hinges to go both ways to allow for mirrored back support? For example, instead of it having an "r" shape, could you make it have a "Y" shape?

that may be bit of an overkill for i3, but I guess I can.
But right now, I'm working on large project so it wont be any time soon.

Can you post the .ipt file? I can do it and send it to you to post here if that would save time

sources are already uploaded for all parts, its designed in freecad
if you make any changes, you can just upload a remix of this thing

Why not try to mount it in the back? Or both?

It seems like it would be more aesthetically pleasing to mount them in the back.

you get better stability when mounting them in front. both is bit of an overkill in my opinion, but you can do it

I am waiting for my MK2 and watching out for improvements. Is it really needed, because noone mentions wobbles in the reviews and the results on the internet look amazing even without the stabilization.

original i3 construction is not firm enough, it is same with both mk1 and mk2.
this is one of two quick fixes to remove significant amount of vibrations in Z axis and improve print quality

Hi Shii. Does the mod improve the print quality (by reducing layer banding lines) to the point of being as good as some of the best CoreXY printers?

You wouldn't happen to have any before and after test prints by any chance?


Cant say, I never had access to any of CoreXY printers.
I dont think I have any test prints from before upgrades I did. But there are more upgrades I did to improve quality and there is still room for more.
But give it a try, this upgrade is quite easy to install.

What are your other upgrades?

most simple and efficient one is http://www.thingiverse.com/make:232894
next was Y-axis remake which you can find among my designs, but that one is lot of work
another helpful one was filament guide, also in my design list
also I replaced all smooth rods and bearings for cnc grade ones and both included idler pulleys with GT2 20T ones.

Customizable Spool Hub Adapter
by Shii

Any suggestion on where to look for the smooth rods and bearings? Any online store/ebay?

I got mine from cnc grade shop due to accuracy, quality and durability. but they dont have english store available.
Pretty sure you can find such around.

For the spool holder I went for this: http://www.thingiverse.com/thing:1688923
Today I added your Z-axis reinforcement and now I'm testing it.
For the Z-axis I might try to switch out the bearings first.

Convenient Spool Holder and filament guide for Prusa i3 mk2

How did the z-axis reinforcement mod go then? Noticed an improvement in print quality?

Yes, the print quality improved. It's not like night and day, but a little smoother.

Oh ok, thank you. So to be perfectly honest, not really that worth it then?

I would do it again.

any spool holder which prevents spool from dangling and thus introducing vibrations to Z axis will do the job.
not sure about one you made. from image it seems like holder is not fully fitted into a spool.

when it comes to bearings, ones from original prusa kit have balls falling out and they leak quite often.
smooth rods on mine were 7.9 instead of 8

I'm looking into buying new smooth rods now.

While my spool holter is not fully fitted, the larger diameter prevents a lot of the dangling. I will anyways upgrade it with the spool holders you linked.

Ok then, thanks for the reply. :)