Prusa MK4 Nextruder gear window

As soon as I saw the Nextruder and the gears on the MK4 I thought it would be nice to see those during printing. So here it is! A Nextruder gear window! 

If you like the idea of a window, but want to use the original washer check out my other design: 

https://www.printables.com/model/456797-prusa-mk4-nextruder-gear-window-from-original-desi

Both mods may also work with the Prusa XL Nextruder.

Printing:

For the window I used clear coverboards with 0.3mm thickness. To get it into the printed part just pause the print right before it is printing over the 2mm lip. Insert the window carefully. The printbed is hot especially with PETG and don't press to hard or you will deform the 3D print. If your coverboard warps, try to print with a lower bed temp. My coverboard started  warping at 85 degree so 60 degree for the heatbed should be fine.

Afterwards hit resume and let the print finish. That’s it! (Make sure you’re Z-hop is high enough (e.g. 1mm), otherwise you could scratch your window)

Note: You can use some drops of hot glue to fix the window into position. Don’t use too much, otherwise you mess up your printhead or bed. (Make sure the coverboard is not higher than the current layer, and look after the printer when it's printing over it!!)

This version is even watertight, therefore dust proof! 

Installation:

To install it, open the idler, remove the four screws. Hold the gearbox in place, that is the easiest way, otherwise it is a bit tricky to get everything back together. Add a bit of grease. Screw in the three screws first and then the last screw with the idler arm. Do not over tighten those! 

More ideas:

With the rectangular visualizer you could go crazy, add tags on it with Prusaslicer or maybe add a Lego compatible base?! I could also imaging some fish “swimming there”, or a submarine/ ship Nextruder? 

Maybe it is also possible to integrate some LEDs and use the power from the love board of the Nextruder, but I guess we have to wait for the schematics from Prusa. 

So, feel free to remix it!

I could also see this technique be useful to print RC-Car windows, or even cheap light microscope sample holders. 

Important notes:

Text is added via Prusaslicer 2.6 alpha6.

Printed in PETG Prusament Galaxy Black with 0.2mm layer height on a Prusa Mini+. Color is done by filament change. White - Das Filament - PETG, orange - Das Filament - PETG

This technique also works with PLA, but should not be used here.

I recommend printing the rectangular 5mm version in PETG with the interface layer. This allows the gears to rub against it. (Add grease!)

Use at your own risk, gears of Nextruder can easily slip of the axis! 

This mod may void your warranty! See comments for more details!

Happy printing!

Update 11.04.2023: 

After printing with this mod for a while, I noticed some debris inside the gearbox. I took everything apart and there is some wear on the printed part.

I tried to solve this by introducing an interface layer with the clear coverboards, so that the gears can rub against it. It turned out to be a bit difficult to print, as the coverboards warp due to the hot bed. So use a lower bed temperature. I tried to print directly on the coverboards on a cold bed but no luck. It will stick but also warp, even if I tape it down.  

The best solution is to insert a second round window right after the first layer. 

Then cutting the middle section out with a sharp knife:

I've added the stl and a template for the circle

Update 19.04.2023:

After printing the RC-Sandy mini with this mod I took everything apart and had a look at the gears again. It turns out that this method with the interface layer works! Although you will have some wear on the layer, there were no debris inside the gearbox. With a bit of grease this should work fine and needs maybe some attention after a god amount of printing. I also added a second version with an easier to cut interface layer. When printing these use a lower heatbed temperature like 60 degree, otherwise your coverboard may warp due to the heat! I've also edited the four corners, they now match the gearbox.

Here are some pictures:

As mentioned above, use at your own risk! This may void your warranty!