Monoprice Select Mini Thumbwheel Leveling System by ahutton1972

Last crawled date: 3 years ago

Update December 22, 2018
A new Version 2 Thumbwheel Leveling System is available here:
https://www.thingiverse.com/thing:3280396
It's much better than this one!
Please consider trying the newer version above as it works much better and is more reliable.
Update February 14, 2018
I've changed this from a work in progress to final. I do not plan on making any other changes to this system unless someone indicates a problem. Several have been successful with this system so I am making the move. Thanks to those that gave it a try in the beta stage!
Update: February 11, 2018
It was brought to my attention that the regular back bracket was missing the countersunk holes for the springs. I've updated the files and recommend everyone update that bracket with the newer file. The bracket without the countersunk is still usable if you use one of the the spring cup washers on the bottom.
Update: February 11, 2018
I've added a version of the front bracket with the magic number layer heights embossed in it. You can choose the original version or the magic number version as you please. No need to print both.
Update: February 10, 2018
I've added a back bracket with an integrated wire harness for those that choose to do the heat bed wire modification. You can use the same wheels with this bracket. It has a slot to hold a zip tie if you wish to secure your wires for strain relief. You choose which bracket you want to use. No need to print both.
Monoprice Select Mini Thumbwheel Leveling System
This is a thumb wheel leveling system I designed for the Monoprice Select Mini 3D Printer. This system is designed to be completely printable on the MP Select Mini and installed without any drilling or modification to the existing hardware. In doing this, the mod takes up some Z-height that you will lose for taller prints. The advantage of this system is that it is easily installed and removed if a larger Z-height is required.
Note: This is a prototype (Beta) leveling system that I may still tinker with based on recommendations and required improvements
Please follow the installation instructions below in order to be successful with this mod. DO NOT attempt to print until you have installed the correctly sized provided spacer
Also, I HAVE NOT tested the z-spacers with a glass bed. Do so at your own risk
Parts List:
4 M2 X 25mm screws to secure to the heat bed. I am currently using M2 X20mm screws and it does work, but you have more flexibility with the longer screws. DO NOT use M3 screws and DO NOT use the current screws used to hold the heat bed. They will not work. Must be M2. I used hex head M2 screws because that's what I had on hand, but you can use whichever head style you like. Countersunk style heads would probably be the best.

4 M2 nylon lock nuts or lock washers. I prefer the lock nuts as they are more secure


4 M2 nuts. 8 if you choose to go the lock washer route.


8 M2 washers to prevent the M2 screws from falling through the heat bed screw holes.

Existing printer springs, cup washers and screws that secure the bed to the y-axis rods
InstallationPlease reference the photos provided when putting together your system.
1.) Print all parts before assembly. DO NOT INSTALL ANY PARTS until you have printed out both the front and back brackets, the thumb wheels, and the necessary spacer.
2.) In order to print the brackets on the MP Select Mini, you will have to adjust your printer settings in Cura (or your particular slicer) to have an X and Y length of 125mm. This is not ideal as the official lengths are 120mm. But in order to print, we have to cheat a little and squeeze out a little more space. Reference the Cura photos. You most likley will not be able to fit a skirt or brim, so if you can print without. Please remember to put your settings back (X:120mm Y:120mm) when you are done. Alternately you can print the brackets on a larger printer.
3.) None of the parts require supports if oriented correctly in your slicer. The bracket should be printed as shown in the photo and the wheels face down.
4.) Thumb wheel assembly: The nuts will tightly fit within the hub of the wheels. You might have to tap them in a little to get them to seat properly. It is HIGHLY recommended that you super glue these in place. Please allot enough time for the glue to dry or the wheel will not be usable. You've been warned. Once the glue has dried, run an M2 screw through the nut a few times to make sure the inner threads of the nut are clear of dried glue. It might take some doing to clean it out but it's not too hard. I don't recommend heating the nuts and melting them in place since this tends to leave them not flush. If the nuts aren't flush with the face of the bed, it will make the wheels very difficult to turn.
5.) Place the wheels into the slots of the brackets. The nut should be facing down.
6.) Attach screws to heat bed: The 4 M2 screws must be securely fastened to the heat bed so that they DO NOT TURN. This is accomplished with the nylon lock nuts or lock washers. Also secure existing cup washers as shown in the pictures. Use M2 washers on the top of the bed to prevent the screw head from falling through the screw hole.
7.) Screw brackets to the gantry. Remove the screws that hold the bed gantry to the y-axis rods. You can do this without harming anything. Just don't move the bed a bunch after you have unscrewed. Place the bracket on the bed and using the same screws, screw the bracket to the bed. Repeat for the other bracket. Please be careful that you install the correct brackets on the front and back.
8.) Assemble the heat bed: Place the heat bed on top of the brackets. The screws should line up with the center of the wheels. If they do not loosen them and re-align until they do. Place the existing 4 springs around the screws and make sure they seat into the depression of the brackets. Press down with the face of your hand on the heat bed until the screws seat with the top of the nuts in the thumb wheels. Turn each thumb wheel counter clockwise until the screw catches in the nut and it holds. At this point your heat bed should be securely fastened.
9.) Install the z-axis spacer: Lower the bed with the thumb wheels as low as they will go. Because the brackets add 12mm to the z-axis height, we have to adjust for this. 3 spacers are available for printing: 0mm offset, 3mm offset, and 4mm offset. The 0mm offset should be used by those that have not added a surface such as glass to the heat bed. BuildTak users, tape users, etc should use the 0 mm offset spacer. If you are using glass or another substrate choose the appropriate width (3mm or 4mm) for your application. Place the spacer as shown in the picture. The spacer clearly labels the correct orientation. It should snap into place.
10.) Level the bed: It is important to note that with this mod there is no play in the bed if the nozzle dives into it. PLEASE USE CARE WHEN HOMING THE NOZZLE AS TO NOT RUIN BOTH YOUR NOZZLE AND HEAT BED. With the bed lowered as low as it can go, home the printer. Be prepared to shut the printer off if you feel the nozzle is pressing to hard on the bed. From this point you should be able to adjust the thumb wheels to level the bed. Again, there is no play in the bed as there used to be. If the nozzle goes too low, it will dig into the bed causing damage. Be sure your leveling is spot on.
11.) THAT'S IT!
I hope you enjoy this mod. It makes leveling a snap and goes a lot quicker than using the Allen wrench. If anyone out there needs a different sized spacer, let me know. I can crank a new design out pretty fast.
As always, if you have any questions or concerns, post in the comments section and I'll get back to you.
DISCLAIMER: I am not responsible for any damage you cause to your printer if you choose to install this mod, whether you follow my directions or not. Install at your own risk. Pay close attention to the height of the bed prior to homing the printer so you don't do damage.
One last thing: If you are successful with this mod, please share a picture here. I would greatly appreciate it.
Happy Leveling!