Monoprice Select Mini V3 (PRO) Manual Leveling Mod

This is a mod that makes the Monoprice Select Mini V3 leveling manual. This gives you the ability to make adjustments to the bed to make it print perfect first layers.

I got a V3 about a year ago and no matter what I tried, I could not get it to recall the leveling when it starts a print and I could not get it to level before a print. Not only that, but it would not consistantly be the same height away from the bed after starting a print. I tried shiming the bed with blue tape to make it perfectly level then running a print and it would not work. This is when I turned to making the printer work with manual leveling.

The first step for this was to make the auto level sensor stop working and have the printer use the Z endstop that is already installed from the factory, I assume as a fail safe for when the sensor does not trigger. To do this, I came across a tutorial on a Monoprice Select Mini Facebook group that showed exactly this. In the photos attached above, you can see how I unplugged the endstop and soldered it into the spliced wires of the sensor. The black wire should be soldered to the black wire for the sensor and the black wire with gray lines on it should be soldered to the red wire for the sensor.

Then I had to take the sensor off and bridge the gap on two solder pads on the PCB. This was easier said than done. I solder quite a lot, but I could not get it to work. The way around it was to solder a wire in and cut it off.

The next step was to get the rivets out of the build plate. To do this, I just took all of the magnets off and hammered the rivets out. I clamped the build plate to a table with the corner barely sticking off the edge and set a hammer on the rivet, then hammered against the end of the other hammer until it came out. Three of them just took one good whack, the fourth took a few tries. I was careful not to damage the build plate. If you are worried, a small hole drilled in wood to align the rivet with may be better.

Then I got some screws and screwed this thing back together. The screws I chose are flat head socket cap machine screws. I did not bother counter sinking the screws because they were low enough with the magnetic build plate I installed that it was not necessary. The springs that I bought were from Aliexpress but they are 0.9mm diameter wire, 15mm total length, and 7mm outer diameter.

Now, you will need to install some nuts. I had some M3 nuts so I used those and I printed something to make sure they do not spin when I am trying to adjust the level. I ended up gluing them in with some E6000. This part is labeled as the “leveling block”. It’s perfectly sized so printing at 101-102% may make it easier to install but it will have to be glued for sure.

Finally, you will have to be careful about how low you push the bed down because the spring loaded heater has some bolts that will easily go too low and get in the way of the Y axis movement. this is where the spacer comes in. I started with the spacer linked below and added a little bit to it to make it tall enough level the build plate and clear the screws with my setup.

Spacer I Modified: https://www.thingiverse.com/thing:1621650