[Bobby Car] Cordless Drill Motor

thingiverse

This is a super cool cordless drill retrofit kit for your classic Bobby Car. It's a game-changer that makes your Bobby Car motor powered, doubling the fun. Now, kids can get even more excited about playing with their favorite ride. My 4-year-old loves it and is comfortable using it. **YouTube Building Instructions and Demo:** <iframe width="560" height="315" src="https://www.youtube.com/embed/6VxZ0sMEa28" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> **Features:** * Mount any standard cordless drill. * Overrunning (oneway) clutch to keep the car still pushable. It also lets the car roll to a stop instead of an abrupt halt. * Powerful and fairly durable. **Component description:** *pulley_wheel*: The large pulley that fits snugly on the rear right wheel. Fasten with 4mm wood screws. *cordless_drill_bracket_hinge*: Print two of these parts and screw them down onto the rear of the Bobby Car. It's a print_in_place part, so break it loose afterwards. The slotted hole on the front might need support for printing. Fasten with 4mm wood screws. Push cable tie through the slot hole. *cordless_drill_bracket_plain*: An alternative version for mounting the cordless drill without hinge. The hole pattern is compatible with the hinge-version. Height is lower. Try this if your timing belt is too short for the other bracket. *pulley_clutch_casing*: Outer casing of the smaller pulley. *pulley_clutch_catch*: Inner part of the overrunning clutch that keeps the balls. *pulley_clutch_spacer*: Small spacer part, that might be needed, if the threaded portion of the M8-screw is too short. **Additional Parts Needed:** * 1x Bobby Car: https://www.big.de/en/products/big-bobby-car/ * 1x HTD470-5M timing belt. I recommend ordering also a shorter and a longer version (465mm and 475mm), to mount the best fitting one. $3 each on aliexpress.com/ebay.com. * 1x ball bearing di=8mm x da=22mm x w=7mm * Superglue or epoxy to glue the ball bearing into *pulley_clutch_casing*. * 4x balls d=6mm * 14x wood screws 4x20mm * 1x Hex bolt M8x50 with nut * 2x bolt M6x16-18mm with nut and washer * 2x strong cable ties **Note:** Although it's working quite well, this is a work in progress. Please contact me if you have ideas for improvements. Also, please let me know if your cordless drill doesn't fit into the brackets. I'll upload different sizes of the bracket if needed. **FAQs:** * Why not use a cheaper GT2 timing belt? Answer: I tried that, but the GT2 belt is jumping over the teeth of the pulleys. It's just too small. * Did you try to print the 6mm balls in place? Answer: Yes, I did. It worked to some extent, but smooth, hard, spherical balls are working much better. **Credits:** The overrunning clutch (ratched) design was based on the model of Corona688: https://www.thingiverse.com/thing:207389 **Printing Tips:** * No support is needed, except for the slotted hole in the *cordless_drill_bracket_hinge*. * Print all parts with 50% to 100% infill to achieve max strength.