This was the first fairy/antweight (150g) bot I designed with my kids. We took some inspiration from the Wedge of Doom and Firestorm. The entire bot was designed using TinkerCAD. Its uses 2 9g continuous rotation servos with 60mm wheels and a 9g servo for the flipper arm. We'll see how well it holds up at its first competition in July 2018. It complies with SPARC rules and fits in the UK spec 4x4x4 cube.
Update: After Competing, it proved much more durable and unfortunately slow than I had hoped. However, I later swapped out the 1s for a 2s battery and a 6v UBEC and it is MUCH faster and had WAY more flipping power. I'm excited for the next competition to give it another try.
Sometimes luck is on your side: https://photos.app.goo.gl/RvtTopsW4HGRmnNaA and sometimes not: https://photos.app.goo.gl/vtm7bEf1XJeAEj1YA
Its always exciting to see my designs in action. Here's an example I found of this bot with what appears to be an added plastic at the bottom of the wedge: https://youtu.be/rh0bbGmGiAI. Relevant parts are at the 4:05, 30:45, and 49:50 times.
I'd recommend at least 3 walls (1.2mm) and then 10% infill for the servo supports inside. You could also print it completely solid, but it adds weight without much strength gain.
Support material is needed for the overhang. Add support everywhere. I was fin with 10% support density and using lines for easy removal.
PLA works fine. I chose to use raptor series for its strength. Other materials should print easily as well.
Print the following:
- Fairy bot main.stl
- Fairy bot flipper.stl
- Fairy bot servo arm.stl
Gather the following supplies:
Gather some tools:
- Pliers for getting the rod in an out
- Screw driver for servo screws
- Hot glue gun
The two continuous servos can be fit into the holes and hot glued into place or use zip ties to secure them using the holes. The flipper servo is wedged in place between the two posts. It can be screwed in place using the holes or hot glued.
Plug the servos into the receiver. The two continuous motors go into Ch 1 and Ch 2. Plug the flipper servo into Ch 3. Program the servos like a delta wing (elevons) or tank. Files for setting this up using the T8SG or similar deviation Tx (https://www.deviationtx.com/forum/model-templates/1308-elevon-and-v-tail-templates-with-dual-rate). Don't put the wheels on just yet!!
I recommend getting a battery plug to keep in the VCC plug on the receiver. The ones that come with the 1s batteries linked about work very well. You may even want a switch to a BEC and a 2s lipo battery for added flipping power and speed. Follow the binding procedures for your Rx. For the Flysky FS-GR3E used above, place the binding plug into Ch 3 (replacing the flipper servo for the time being). Plug in the battery to power up the Rx. The red LED should be blinking quickly. Turn on the transmitter and follow its Flysky bind procedure. For the T8SG, go to the model menu and scroll down to the bind button and press ent once highlighted. The blinking LED on the Rx should stay solid. Remove the bind plug. Unplug the battery and turn off the transmitter. Plug in the battery and turn on the transmitter. You should be bound and have control surfaces responding to your control inputs.
With the servos powered and in the neutral position, screw the flipper arm onto the flipper servo. Make sure flipper is as close to the bottom of the bot as possible. Push the 2mm steel rod through one hole in the body, through the flipper and finally through the other side. The flipper should be facing up The round edge fits within a groove underneath the lid or the bot. A little bit of metal should protrude from both sides. Pliers make this job much easier. Make sure the flipper rises and falls freely. It should close completely. You may need to adjust the servo arm if it doesn't. Test the flipper arm motion. If wires are in the way tuck them out of the way.
Screw each wheel into place. Test the elevon mixing your programmed earlier. You may need to swap Ch 1 and Ch 2 physically or do some reversing in the transmitter menu to correct for deviations from the expected inputs (eg up: both wheels move together propelling the bot forward....down: both wheels move together propelling the bot backward...right: the bot turns right....left: the bot turns left.)
Tuck all of the wiring into the back first. Then place the receiver and the battery inside. I recommend hot gluing the receiver in place. Test to make sure the bot works as expected. Add some aluminum sheeting or other shield/weaponry/decorations. Have fun and share your experiences so we can all benefit, learn and improve.
Add the servo arm
Plug servos into the receiver and tuck away the wires in the back. Add battery connector. Plug in the battery and tuck it away.