Neptune 3 Pro upgrades

I figured I might as well document the mechanical and other upgrades I've done to my Neptune 3 Pro, rather than just my Klipper setup.

The purpose of this article is to share what I've learned, in the hopes that someone else finds it as useful as I have.

Worth noting that everything here is written from the perspective of already having a working Klipper install. The instructions may apply to non-Klipper setups, but that is not my priority.

Manual bed leveling

I ran into some issues with the bed leveling on my printer, which were highlighted by Fluidd's visual representation of the bed mesh. I wasted a lot of time making shims for the bed out of aluminum foil and paper, and I was only able to get the bed level ranges down to the 0.5mm variance range. With the addition of adjustable, manual bed leveling, I have brought it down to 0.07mm variance.

I found a Reddit post detailing how to do this, and so I did essentially the same thing the OP did.

Parts to order

This kit, only for the included adjustment wheels, and the screws which I did not have a lot of spares of.
This set of silicone spacers.
Heat tape to cover the electrical contacts on the bed.

The upgrade

Remove the PEI sheet, and then the four M4 screws that attach the bed to the sliding platform.
Remove the plastic cover that is employed to protect the 24V power lanes on the underside of the bed.
Use a drill with a 5/32" drill bit (or vaguely equivalent) to widen the four mounting holes on the sliding platform, as the holes are M4 threaded and we need the new screws to pass through the holes easily.
Deburr the holes with a countersink bit, a file, or whatever is handy.
Set four of the silicone spacers over the four freshly widened holes. I noticed that the spacers had a wider opening on one side; I chose to face those upward.
Carefully set the bed back down on top of the spacers.
Run the longer screws from the leveling kit through the holes. I chose to use the shorter set of screws that came with the wheel kit.
Spin the four knobs onto the four screws underneath the bed and sliding platform.
I chose to insert the four stainless steel factory spacers between the bed and platform, and adjust the wheels until the bed just barely pinched them, in order to get as close to the factory height as possible. You could certainly do this with a caliper instead.

Leveling

Danger

Re-adjust your Z offset! If you are using Klipper, run PROBE_CALIBRATE. I like to adjust my Z while the printer is hot, personally, and adjust until it very barely drags the paper. In fact, I did this entire section hot.

Note

I used nothing other than Klipper's bed mesh feature. I'm sure that I could have accomplished more with the Manual Level features, or even BedLeveler5000, but I wasn't about that life for this project. I think my results are quite good regardless.

Once your Z offset is roughly dialed back in, home your axes and visit the Tune tab.
Load your old bed mesh, and for fun, write down your current Range value.
Update your mesh.
Spin your fresh bed mesh so that 0,0 is at the near left of the visual.
Adjust the knobs a quarter turn up or down at a time as needed and rerun the mesh update.
Continue running the mesh and then adjusting the knobs several times until your Range value is where you want it.
Run SAVE_CONFIG.