Spooky R/C Tricycle

Hello fellow Halloween aficionados,

This R/C tricycle was an absolute blast to make but that doesn’t remotely compare to the sheer joy I got taking it out Trick or Treating. The crowds loved it / were terrified by it. I bet 500 people took selfies with it or videos of it. I saw tons of Facebook posts featuring Billy throughout the next week. I also chased a group of teenage girls at the insistence of one of their fathers, which he and I got a good laugh out of. Isn’t that what Halloween is all about: Laughing at screaming terrified children?  

As with most things on the internet, I’m sure ample people smarter than I will come by and point out how I could have done things better. No worries, I’m just a dude who likes tinkering in my garage and making cool stuff. This isn’t THE way, it’s A way. 

I’m going to focus on the R/C tricycle part as you can use various characters (or just the trike itself) and it’s all equally cool. I did mine in a “Billy Jigsaw/ Saw” theme. If I have time, I’ll drop a separate Instructable with all of that info and the files I used. A $5 plastic skeleton would be just as cool and save you hundreds of hours of 3d printing and wiring. An empty “ghost” tricycle is equally scary.

This is not a movie-accurate replica. I made it my own.  

I present to you, one way to do it.

1. Radio Flyer, Classic Red Dual Deck Tricycle, 12" Front Wheel, Red
2. This is not movie accurate but the 2nd deck helps hide the various wires/electrical components and also provides structure.
3. 2x IG42 24VDC 240 RPM Gear Motor with Encoder from Superdroidrobots
4. I would not have gotten motors with encoders if I had a choice. They were sold out of non-encoder motors at the time.  
5. I went direct-drive (wheels attached directly to the motors). I’ve seen other great belt-drive versions.
6. Other hefty motors will work. I went with 24v for power and torque. I can take my trike off-road without issue. Sufficiently sized 12v motors would work for roadways / sidewalks. 6v motors probably won’t work.
7. ATR Wheel Shaft Set Pair 8mm Bore - 6 inch pneumatic from Superdroidrobots
8. 6 inch wheels are small but I wanted to stay as close to the original tricycle aesthetics as possible.
9. 2x Motor Mount Tube - IG32 or IG42 SB from Superdroidrobots
10. Doesn’t have to be these but these were super simple. Get whatever motor mounts fit your motors. SDR is awesome!
11. 2x Motor Mount Plate - IG42 from Superdroidrobots
12. I neglected to get these originally and had to make a second order, which delayed my project a week. If you get the motor mount tubes above, get these mount plates too. Be smarter than me.
13. Sabertooth 2X12 R/C motorcontroller. 
14. I had this laying around my garage, don’t remember the original source.
15. https://a.co/d/8TfeWC1 Cheap RC transmitter and receiver from Amazon. 
16. Doesn’t have to be this one, but I love this thing. It's tiny. I was able to comfortably hold it with 1 hand inside the kangaroo pocket of my hooded sweatshirt and most people had no clue who was controlling Billy. Range is awesome.
17. Random red LEDs. 
18. I think I originally got these for a drone project. Totally unnecessary but really makes everything pop in the dark.
19. 2x 3s Lipo batteries
20. I used 2 x 3s 2200mAh batteries wired in series. I can drive Billy for 2.5 hours without issue.
21. Rustoleum Regal Red spray paint
22. For touchups, painting screwheads and covering the original logo. It didn’t feel right to leave the logo visible.
23. 24v toggle switch
24. Some 3d printed parts
25. I’ll attach my versions below. I’m sure they could be improved on and I’d love to see how anyone makes them better.

I started by assembling the tricycle in its original form so I had a feel for what I was dealing with. Then I took it back apart so I could mess with it. I’m a hands-on person so this helped me. YMMV.

I mounted the motors to the motor mounts and checked for clearance. There was barely enough space between the outer edge of the deck and the center post. Motors without encoders would help here. I marked the bolt hole locations and drilled them out. I did have to trim a small half-moon on the edge of the deck to get everything mounted flush with the deck. The wheels hide these cuts.

I measured the lipo battery packs and Tinkercad’d (is that a verb? It should be) some mountable battery boxes. I'll pause for a second so you can revel in my ability to make a hollow rectangle using basic free CAD software...

I’ll share my battery box below but obviously you’ll have to re-size for your application. If you didn’t know that without me typing it, this project might get rough. 

I mounted the lipo boxes next to the motors, which isn’t ideal for heat purposes, but it’s where they fit. It's cold here during Halloween and I don’t drive Billy at max throttle constantly. They’ve held up just fine.

I figured out where I could fit the motor controller, drilled holes and mounted that.

The steering was the hardest thing to figure out. I read every Instructable and various projects on other websites for builds that were similar and those all either used extremely expensive steering motors (like $300+) or the mechanism was extremely visible. I spent way longer than I care to admit (months) designing and testing various methods. Then I had an epiphany: I mounted a strong Servo motor (35Kg) in a custom 3d printed bracket to the center bar, under the seat. I then mounted a 13 in flat bar to the servo, perpendicular to the center bar. This became the steering bar. 

*I did wrap the center frame bar of the trike with electrical tape, which seemed to give the 3d printed bracket something to "hold on to". Without the tape, there was a little bit of bracket wobble.

Fair warning, I was challenged by how much to tension the paracord. Too much tension and it wouldn’t achieve the full range of motion. Too little and the front wheel wobbled. I’m sure there’s a math formula out there that would solve this easily, but I don't know it. I spent like 3 days trying to figure that out. Then I spent 30 minutes of trial and error and eventually found a winning combination. My advice is to proceed with reckless abandon over math.

My hack to make everything work was to use 1 inch loops of stretchy/rubbery paracord at the steering bar connection point. That gives that extra bit of wiggle room to hold it steady yet allow full range of motion. These 1 inch stretchy loops then connect to a "main line" regular paracord that runs up to and connects with the handle bars. Pictures are worth 1000 words here.

This resulted in something similar to a kiteboard control bar. I know nothing about kiteboarding, that's just the most similar thing I can find. Small movements of the steering bar result in larger movements of the handlebars. This allows the tricycle to have full range of motion. Once the steering bar is painted red and the tricycle seat is installed, the steering bar is fairly hidden. 

When the sun starts to set, the paracord and steering bar become invisible.

I wired everything up, including a on/off toggle. In the picture, the toggle is wrapped in blue painters tape.

This is probably self-explanatory but with the Sabertooth, the motors wires go into the motor controller (MC). The Lipos get wired in series with the negative going directly into the MC and the positive going to the on/off toggle. The other terminal of the on/off toggle goes to the MC. The Sabertooth manual is very comprehensive and if you aren't familiar with them or how to wire them, you should be referring to that manual and not some guy on the internet.

For anyone interested, my Sabertooth2x12RC dip switches were 1-UP, 2-UP, 3-Down, 4-UP, 5-DOWN, 6-UP.

I mounted the RC receiver on the centerbar between the upper and lower deck. I just hot glued it and threw a zip-tie on as backup.

Once I was done with all the mechanical parts, I gave everything a coat or 2 of spray paint to hide boltheads.

I added some red LEDs to the underside of the upper deck and front wheel well. I ran the wires inside the centerbar frame. I wired these to a red on/off toggle switch. I powered them from a small voltage converter set to 5v. The LEDs aren’t necessary but they make this thing pop at night. It also helps me see the trike and people see it coming.

Once everything was working well, my kids and I drove Billy to our local gas station. We stood back and watched until the clerk noticed it driving through the lot. She was appropriately spooked, although suspected something was afoot based on my phone call to her suggesting something weird was outside. I know the clerk, and she's a friend. I also knew she was working (that seems relevant).

She was kind enough to share the attached security footage with me the next day. 

She hilariously left a note for her dayshift boss saying "something creepy happened at closing time" with no other details and left it to him to review the camera footage. I’m told there were serious debates /arguments about whether Billy was a real kid on a tricycle, a prop or (half-seriously) a ghost.

I knew I had a hit based on the 15 or so cars that slowed way down to check it out. I saw multiple cell phones taking pictures/videos of it from the road. I told my kids we had to get off the road or there was gonna be a crash. 

Watch the road people, not creepy haunted tricycles in the bike lane.

This took way longer than I ever imagined. I started in July and was still making final tweaks on October 31st, an hour before we had to leave to go Trick or Treating. It didn’t have to take this long but I kept dreaming up ways to improve it. I’m super happy with how my tricycle came out and it’s become a local “celebrity”. It was totally worth it all the time and effort put into it. It was an absolute hit on Halloween and I can't wait to take it out again this year. It's available to rent for parties and weddings (not really, although....)

Everything doing is worth overdoing and moderation is for cowards. 

Good luck if you decide to try something similar. Drop a link below as I’d love to see other people’s builds!!!

Thanks for checking this project out.

These are my 3d printed files. There weren't designed by a 10 year old I swear. I'd love to see how people improve on them!