BB-8 remix with dummy internals

thingiverse

I was beyond thrilled as anyone when I found out they built practical, working BB-8s for the new Star Wars, but I'm not really "$150 toy" excited, and I couldn't even justify spending $50 on a used Sphero to disassemble it. So, I decided to build upon the work that's already been done here on Thingiverse. My goal was to build a BB-8 using only printed and hardware store parts that could roll along the floor and keep its head upright, and spoiler alert: it finally works! I made some initial modifications to the existing parts, adding holes for 1.75mm filament in the ball halves so it can snap open and closed repeatedly and in the head to make antennas. The hardware store parts are 19mm ceramic disc magnets, 9 7/16" ball bearings, 2 8mm OD/3mm ID/4mm wide roller bearings from old spring-loaded extruders, and 3 #4 x 1/2" screws. I experimented with 3 different heights for the magnet within the central "stalk." At its highest, the whole internal assembly just stuck to the head through the ball. At its lowest, the magnet wasn't close enough to keep the head from just falling off. I've settled for a position right in the middle of those two, but it might be worth printing a version that puts the magnet a millimeter or two higher or lower. I then thought there might just be too much friction acting on the internal mechanism. To fix this, I added a few modifications to reduce the friction and make the mechanism move more smoothly. The non-printed part list for this version is still the same: 12 1oz fishing weights, 4 19mm ceramic disc magnets, 4 3/4" ball bearings, and 2 #4 x 1/2" screws. The next version will have a fixed axle at the center rolling on skate bearings. I think this design change will improve the overall balance and stability of the BB-8 model. Version 5 is actually really good! Even the cheapest eBay bearings roll more smoothly than ball bearings running in a 3D printed race that I sanded for maybe 15 minutes. Maybe it also helps to have a fixed, defined axis for everything to rotate around. It actually doesn't work nearly as well not when I've painted it, but I'm still satisfied. The final non-printed parts list is: * 10 1oz fishing weights (pictured now) * 6 #4 x 1/2" screws * 4 19mm ceramic disc magnets * 2 608ZZ bearings * 2 M8 25mm bolts * 2 matching M8 nuts The cost, even including all of the ball bearings I ended up not using in this final design, is probably less than $20. If I put a value on the TIME I put into all the previous designs, maybe a bit higher. **Printer Settings:** * Printer Brand: MakerBot * Printer Model: MakerBot Replicator 1 * Rafts: Doesn't Matter * Supports: Doesn't Matter **Post-Printing Instructions:** There's a lot of sanding and drilling to open up holes necessary. You'll need a few inches of 1.75mm filament to cut up into pins. **Custom Section: Assembly Notes** Determine the orientation of your magnets and mark them before you trap them inside the head or the internal mechanism. Install the magnets in the cap and screw it down. Use the bolts to push the nuts into each side of the pivot. Try to lay out the weights in the bin in a symmetrical pattern for balance, you may want to glue them in place. Fitting all of the internal pieces into the "barrel" of the ball is difficult but not impossible, and once you're in there you will find that I forgot to leave enough room for a screwdriver, so that's fun.