Mini 3D Spacemouse w/ Hall Effect Sensors

I designed a smaller version of John Crombie's "CAD mouse / Spacemouse using Hall Effect Sensors" with my original TPU spring suspension. The body is only 30mm high, where 10mm of it is just the base with ballast compartment.

Material list:

• x1 Arduino Pro Micro USB Type C

• x3 6x6x4.3mm Tactile micro switch

• x8 49e linear hall effect sensors

• x4 10x5x3mm Neodymium magnets

• x6 M3x16 Countersink screws

• x2 M3x8 Pan head screw

• x8 M3x4 heat-set inserts

• x1 M4x30 Hex Socket Head Cap Screw Bolt (full thread)

• x1 M4 nut

• x1 M4 washer

• some 23AWG/24AWG wire

• some thin heat shrink tube

• ~250g lead shot 2.5mm balls (optional ballast)

Parts to print list:

• x1 Case        (w/ supports)

• x1 Base

• x1 Chimney (w/ supports only in the center hole)

• x1 Arduino plate

• x1 Knob       (w/ supports)

• x1 Hat          (w/ supports)

• x3 Button    (w/ supports)

• x1 Magnet plate spring (print in TPU with 100% infill and add pause to insert magnets)

Incoherent and disorganized rambling - a.k.a. build instructions (good luck!):

To build the mouse you will need to solder the wires to the sensors and to the Arduino board, install the heat set inserts, and flash the firmware. Please use the same schematic as the original spacemouse from John (links on the bottom) but do not use servo plugs as there is no room for those. Solder the wires directly to the sensors. When printing the magnet plate add a pause in the print at the very top of the pockets to allow inserting the magnets. Make sure the polarity of the magnets is correct. You can check that with the sensor after soldering everything together. Instructions in John's post. There are two files for magnet plate. One is for magnets that are on size (10x5x3mm), and the other one is for undersized magnets, like mine were (9.5x4.5x2.5mm). Pick the one that best suits your magnets size. Clean up all the printed parts from the supports and any blobs on the edges and add heat set inserts. Pay most attention to buttons on the underside as they will have tight tolerance during assembly.

Assembly:

I've recorded myself putting the mouse together. I hope the video answers most of your questions, but just in case you have any, please ask them in the comments. I will try to answer them all and update the description. Written instructions under the video.

To assemble the mouse you will need to solder and test the electronics first before you commit to putting it all together. It will be really hard to fix anything later. Make sure the wires on the board are soldered neatly towards the middle of the board and that there's no excess solder on the underside of the board. Leave the wires for the buttons unconnected for now. Screw in the main M4 bolt into the central hole in the "Chimney" and secure it with a dab of superglue. Insert the tactile switches into the slots in the "Chimney" part from the top, then solder the wires to them from the bottom. Thread the sensors through the chimney and bend a 90° on the ends, and insert them into the slots. Make sure to keep the sensors order correct. Test the sensors using the debug mode 1 to check the order. Now After installing the sensors, insert the Arduino board into the "Arduino plate". Tidy up the wires and put the "Chimney" onto the "Arduino plate". This is where you can optionally fill the base with ballast. I suggest ~250g of 2.5mm lead shot. Pack it as tight as you can but do not overfill it as this would cause the mechanism to distort and jam later (this part is not in the video as I haven't receiver the lead shot in the mail yet at the time). Now you can bolt the assembly onto the base with x3 M3x16 countersink bolts. Install the heat set inserts into the magnet plate and thread it onto the main M4 bolt. Make sure the polarity is correct. If you correctly inserted the magnets during print, the side on the print bed should be towards the sensors. Add washer and nut and torque it down until the center stops rotating when you rotate the outside. Put the "Knob" onto the magnet plate and press it firmly down to seat it completely onto the plate, then screw it down with x2 M3x8 bolts. Do not put the "Hat" yet. Clean up the slots for the buttons on the "Arduino plate" with a small file or Exacto knife (there will be some droop in the bridging during printing). Insert the buttons into the slots and make sure the switches are clicking nicely and don't get stuck. If they do, take the button out and shave it off from the bottom where it meets the switch with a knife or a file and try again. When the buttons are working fine, put on the main case. It's a little bit fiddly, it doesn't go on easily. Start mostly flat but then angle it slightly towards the USB port and sneak it in. Then press gently for it to snap into place. You can jiggle the buttons around if that helps. When the case is on, bolt it on from the bottom with 3 more M3x16 screws.

Calibration:

After assembling the mouse you will need to follow the same steps of calibrating the firmware as in the original. If after you follow the instructions for calibration you still have high cross-talk between roll axis and move axis (can test it with debug mode 4), try loosening the nut and clocking the magnet plate slightly left or right, then torque it back down. After each adjustment reset the hall sensors from debug console (type "11") and test again. It will never go away, you can only minimize it. When you're happy with your calibration (or you just gave up), you can put the "Hat" on and enjoy your new mouse.  

Links:

https://www.printables.com/model/940040-cad-mouse-spacemouse-using-hall-effect-sensors

https://github.com/ChromeBee/Hall-Effect-Sensor-CAD-Mouse-Spacemouse

https://github.com/AndunHH/spacemouse