Desktop Frisbee Launcher

Here’s how to build my first iteration of a launcher that throws Discraft Mini-Star Ultimate discs. You could call this the quick and dirty version. It’s really basic. All it does is shoot. But, it could easily be modified to do more. And that’s the plan for later iterations. I’ll add complexity and make it a more dynamic thing.

This is my version broken down. What you read below is going to be a little different. Simpler, and easier to construct. For video, see here: https://vimeo.com/149931779

WordPress no longer supports my Vimeos.

The instructable can be found here: http://www.instructables.com/id/Desktop-Frisbee-Launcher-With-Wii-Nunchuck/

IMG_0925

Discs: Discraft Mini-Star — http://www.amazon.com/Discraft-Mini-Star-disc-Set…

Motor: I used a 12VDC 5310 RPM brushed motor. From other versions online I gathered that the motor speed needs to be around 5000 RPM to get good rotation on the disc as it exits the chute. You shouldn’t need quite as heavy duty a motor as i have here, but I’m not an engineer and wanted to make sure I was going to have the torque I needed. — http://www.robotshop.com/en/12v-5310-rpm-cim-brus…

Power Supply for Motor: A 12V 20A power supply is what you’ll need for this big honkin’ motor if you get the one I used. Make sure it’s 20A! Although the motor needs less than 3A to run unburdened, and spikes at less than 4A when the disc goes through, it’s initial draw to start up is 16A. So any other power supply won’t hack it. You’ll never get the motor started. Look at MeanWell switching power supplies on Amazon.

Repair/replacement 3 prong power cable – Your power supply won’t come with a power cable. You’ll need to wire it up. You can get one of these easily at a place like Lowe’s or Home Depot

Flywheel: https://www.adafruit.com/products/167

ply-wood: 4’ x 4’ x 1/4” or 1/2” – This will be more than enough material, but it’s probably the average sheet size you can get at your local hardware store.

Arduino Uno set with breadboardhttps://www.adafruit.com/products/170

Extra wire – I had access to both solid core and stranded in multiple colors. 4 different colors should be enough. In this case we use red, blue, green, and black.

1 diode – 1N4001 (in Adafruit’s Uno kit)

1 2.2KΩ resistor (In Uno kit)

1 TIP 120 Transistor (separate from kit)

9V battery adapter for the Uno (in kit)

9V battery

1 WiiChuck adapter for Arduino – The original is from todbot through SparkFun. That’s what I bought. He has links here:http://todbot.com/blog/2008/02/18/wiichuck-wii-nu… But in future iterations, I’ll probably use the sturdier clip-in model from Solarbotics. You can get it through adafruit, here: http://todbot.com/blog/2008/02/18/wiichuck-wii-nu…

1 Wii Nunchuck joystick controller (avoid 3rd party models)https://www.adafruit.com/products/342

soldering iron and solder

electrical tape

electric drill

wood screws (1/2”)

a drill bit set for wood

#8 machine screws (to match mounting holes on motor)

5 minute epoxy

Multimeter

calipers are handy, but not necessary

Step 2: Cutting Parts for the Box

First, let’s build the box. You can wire it all up once the motor’s been mounted, and it will be easier to test when it’s stable.

I’ve included two .PDFs. The first shows the dimensions if the thing were made entirely of 1/4” plywood. The second .PDF is to use if you were to cut your other parts on the CNC router or laser cutter. The top and bottom are the same dimensions and should always be plywood.

Now, using a table saw or circular saw, cut everything to size. With the curve for the chute, cut a square blank. Then, print and use the .PDF as a paper template. Place it on top of the square blank, trace the curve onto the surface of the wood, then cut to the line with either a band saw or jig saw. If necessary, follow up with sanding.

If you don’t have access to a band or jig saw, but have a cnc router, you can use the router to cut just the chute curve. It would be wasteful of time and energy to use it to cut squares unless you absolutely had to, though.

Step 3: Drill holes to put the thing together!

You’ll want to drill holes for all your wood screws. For the side walls, drill holes that are larger than the size of your screws so they come in and out easily. For sides A and B, put holes in each corner 1/2” from the sides, and 1/8” from the top or bottom (1/8” will line them up with the middle of the edge grain on the top and bottom pieces). For sides C and D, put holes in 1.25” from the sides and 1/8” from the top and bottom. Then, in the edge grain of the top and bottom faces, you’ll want to drill pilot holes. You can mark the center points for these holes using the ones you’ve already drilled. Just make sure that these holes are small enough for the threads on the wood screws to catch, but not so small that the screws split the laminates on the plywood.

You’ll follow the same procedure for drilling holes in the chute curve.

Step 4: Drill holes for motor mount

Your motor holes will go in the top face. To drill holes for the motor, start with the center hole. Drill a hole slightly larger than the diameter of the shaft to prevent rubbing of materials. Then, drill holes at the appropriate distance from the shaft to line up with the mounting holes for the #8 screws.

Here’s a .PDF that you can use to mark points for those holes relative to the curved chute. The shaft hole goes at point C, and the holes for the mounting screws go at appropriate distances on line A-B.

Step 5: Put the box together

Now, start putting the box together. We’ll start with the top and sides A, B, and C. This will leave side D and the bottom open for putting the motor in. Screw A, B, and C together. Through side D, go ahead and fit the motor in and mount it with the machine screws. Now, you can put the bottom on, but leave side D completely open for wiring.

Step 6: Wiring up the WiiChuck to the Uno

Now, let’s take a look at the Arduino Uno. It’s time to wire this thing up! We’re going to do this in two stages. First, we’ll wire the WiiChuck to the breadboard, then we’ll wire the motor to the breadboard and power supply and tuck it all away.

First, wire your breadboard to the 5V and ground. Run 5V to the positive (+) column and GND to the negative (-) column.

Now solder 4 male header pins directly into the WiiChuck adapter and then just stick it into the breadboard. Once you’ve done that, all your wiring can come and go from the breadboard. You’ll connect C to Analog input pin 5 and D to analog input pin 4. Then you’ll connect “+” to positive on your breadboard, and “-” to negative on your breadboard.

Running everything through the breadboard instead of direct to pins will allow you to easily introduce servos or other things into the system without having to start over later if you want to add some functions to the Nunchuck, or just use it for something different altogether.

Step 7: Wiring the Motor

For the motor, because you don’t need power from the uno, you can wire directly to the pins you need. In our code, we’re using pin 9 to control the motor through the nunchuck, so we’ll plug directly to pin 9. And we’ll plug our negative directly to ground.

Now, before you do this completely, you’ll need to check the polarity of your motor, because once you introduce the transistor and diode, the current becomes directional. And you can’t just switch positive and negative to run the motor the other way. It will cause really heavy amperage draw at low voltage.

So, let’s wire up the power supply. Using a standard replacement cable from the hardware store, it should have standard coloration. Green for GND, White for Neutral, and Black for Live. Please consult your packaging or a reliable internet source if this coloration is not the case.

First: DO NOT PLUG ANYTHING IN — Always make sure everything is turned off before adjusting wiring on any electronics.

2nd: Make sure the switch on the side is set to 115V. It should be easily adjustable with a toothpick.

3rd: Connect green to GND, white to N, and black to L.

4th: Connect to a surge protected power strip that’s plugged into the wall, but turned off. Then turn on the power strip. The green light should come on. This means the supply is functioning correctly.

Now, if you’ve got a multimeter, which you should probably have if you’re doing any kind of power related wiring, you can touch red to positive and black to negative to get a reading. It may not read exactly 12V. If not, you can use a phillips head screw driver or similar tool to adjust a little dial next to the green light. Adjusting that dial will “dial” in the voltage to the desired 12V.

Remember why we did this now? So we can check the polarity of the motor. You want the motor to spin clockwise. So connect it up to the power supply and see which orientation matches clockwise. Screw it in as if you’re wiring it permanently, don’t just touch it to the supply. Then flip it on. If you need to wire it positive to negative and negative to positive in order to get the correct direction of rotation, you’ll need to switch that around when you read the diagram to wire it to the Arduino. If for some reason your motor does need to run “backwards” all you ned to do is flip the wires before you get to the diode in the diagram. Connect red to the black end of the diode and black to the silver end of the diode. Do not change the color orientation after the diode. This way, you’re always wiring red to positive on the power supply and black to negative on the power supply.

Step 8: The Code

Before everything gets buttoned up, the code needs to go into the UNO. I based my work on a set of code for a nunchuck controlled rubber band gun that ran three servos. Eventually, this disc shooter will function on multiple axes.

First, you’ll need to have a few libraries. Two of them should already be available in your Arduino programming on your computer. Those are Servo.h and Wire.h. They’ll already be in your libraries list. The one you’ll have to add is attached to this instructable. It’s called nunchuck_funcs.h

You’ll need to add an actual folder for it into your libraries folder. On a mac, you can unzip the file right into your libraries folder: documents > arduino > libraries.

I’m giving you the file, because the versions out online lack the correct syntax. They haven’t been updated it some time, and many of the sites where these files originated are gone.

From there, just copy and paste this code into your Arduino window! This code has potential to allow you to do much more than just fire up the motor. But that overcomplicates things for what this prototype is trying to do. I’ll add more later.


#include #include #include "nunchuck_funcs.h"

int loopCnt = 0; int bang = 9;

Servo LR; //servo for Left-Right movement Servo UD; //servo for Up-Down movement

byte accX, accY, joyX, joyY, zbut, cbut;

void setup() { UD.attach(10); pinMode(bang, OUTPUT);

Serial.begin(19200); nunchuck_setpowerpins(); nunchuck_init(); Serial.print("WiiChuck: Let's Do This!!!\n"); delay(100); }

void loop(){

if (loopCnt > 200) { loopCnt = 0;

nunchuck_get_data();

zbut = nunchuck_zbutton(); cbut = nunchuck_cbutton(); joyX = nunchuck_joyx(); joyY = nunchuck_joyy(); accX = nunchuck_accelx(); accY = nunchuck_accely();

if (zbut == HIGH) {digitalWrite(bang, HIGH);}

else {digitalWrite (bang, LOW);}

}

loopCnt++; }

Now, you can hook the power supply back up and test your nunchuck control of the motor. It should only power on when you press the Z button.

Step 9: Box it up and put on the fly wheel!

Now you’re ready to slap the last piece of the box on. You’ll want to do one thing though. Cut a notch out of the last of the four walls, so that all the wires you need access to can get out. you’ll need the nunchuck cable to come out of the box and the wires to the power supply (which should sit outside of the box so it can breathe) should also come out.

Once it’s packaged up there’s only one thing left. You want to put the flywheel on.

Unfortunately, this fly wheel is meant for servos, not DC motors, so you’ll need to drill out the center a little bit. A wood bit should do this just fine. But, be careful! You’re going to need to clamp the wheel down really well. Get the diameter of your motor shaft and drill a whole the same size. If you’re lucky, it’ll be so perfect, you can pressure fit it to the shaft and it will be tight enough. But, what’s more likely is that you’ll have to drill it ever so slightly larger like I did. In this case, get that 5 minute epoxy and glue the thing on so it sits up just high enough not to rub any of the box or the screws to the motor underneath. Also, don’t glue it to any of those things either. Take it easy with your glue! ADVICE: Wear nitrile gloves so you don’t get any on your hands.

After a little under an hour, the glue will be set and you should be able to give this thing a whirl!