The lunch decider wheel is basically a carnival-style wheel that spins every day at 11:45am and selects what is for lunch. It came about on account of my perpetual indecision on this very important culinary matter. In fact, this device does more than just decide what I should eat for lunch, but provides two very important public services. For starters, it selects what everyone will be having for lunch; eliminating the need for surplus cognitive work. Secondly, it prevents me from asking all of my fellow coworkers what I should be eating for lunch (much to their relief).
This project uses some serious hardware such as an industrial-scale magnetic clutch that I purchased directly from a Chinese factory and a 400w laser cutter that I used to cut up the plywood. Of course this project can still be built without these things. It would just require slight modifications to the design and construction process. I did not exactly reinvent the wheel; I just automated it and forced it to pick lunch for me.
Step 1: Go Get Stuff
(x1) 12V DC car seat motor (or similar)
(x1) 24V magnetic clutch (aliexpress)
(x1) Arduino Uno (Radioshack #276-128)
(x1) PC Board (Radioshack #276-150)
(x2) 12V relay (Radioshack #275-001)
(x2) TIP31 transistor (Radioshack #276-2017)
(x1) SPST momentary pushbutton (Radioshack #55050585)
(x1) LM7805 5V regulator (Radioshack #276-1770)
(x1) 10uF capacitor (Radioshack #272-1025)
(x1) 0.1uF capacitor (Radioshack #272-135)
(x2) 1N4004 diodes (Radioshack #276-1103)
(x1) 10K resistor (Radioshack #271-1126)
(x2) 1K resistor (Radioshack #271-1118)
(x12) Quick connects (Radioshack #64-3131)
(x1) M-type power jack (Radioshack #274-1569)
(x1) 12V @ 2.5A power supply (Radioshack #273-318)
(x2) 12V rechargeable batteries (Radioshack #23-943)
(x1) DS1307 real-time clock module
(x1) 1/2" x 3" metal tube
(x1) 3" nylon pulley
(x1) 3D printed pulley (print file)*
(x1) 3' x 3/8" round belt
(x3) 6-32 x 1" spacers
(x4) 4-40 x 1" bolts and nuts
(x8) 6-32 x 1" bolts and nuts
(x12) 1/4" bolts
(x8) 1/4-20 x 1" bolts
(x2) 4 x 8 x 3/4 plywood sheets
(x1) 4 x 8 x 1/4 plywood sheet
(x1) Assorted shrink tube
(x1) Assorted zip ties
*If you do not have a 3D printer, you can get one from Radioshack or have the part printed using a service like Shapeways.
Step 2: Cut Wood
However, I understand that most of you don't have access to a 400w laser cutter able to blast through 3/4" plywood with a giant laser beam. Please keep in mind that you can cut these wood pieces the old fashioned way with power tools like saws and drills.
Even though the future is now upon us, you fortunately still don't need a laser to follow plans and cut plywood. Download the attached files for plans and dimensions of what needs to be cut, and then cut it out.
Step 3: Motor Shaft Extension
Step 4: Mount the Clutch
Insert the clutch into the mounting hole and then place the other part of the pedestal horizontally on top.
Insert the corner brackets at each of the corners.
Step 5: Bolt
Step 6: Fasten
Fasten them together with wood screws.
Step 7: Measure and Mark
Repeat this on the opposite edge of the base.
Center 2 x 4's along the inner edge of these lines such that they are parallel to the center slots.
Step 8: Spacers (optional)
Basically, cut the spacers using the attached template, place the casters atop each one, and trace the mounting holes.
Step 9: Drill and Fasten
Once all of the holes are drilled, mount all of the caster in place using wood screws.
Step 10: Attach the Bottom Plate
Center the pedestal support plate on the underside of base such that it covers the mounting slots.
Drill pilot holes in each of the corners of the pedestal support plate and fasten it down with 1-1/4" wood screws.
Step 11: Attach
Fasten them together by sinking wood screws through the pedestal support plate mounted on the underside of the base up into the bottom of the pedestal.
Step 12: Drill
Drill a 5/8" mounting hole 1" from the opposite end of the aluminum bar.
Step 13: Fasten and Press Fit
Also, download and print out the attached plastic spacer. This is designed to fill in the gap between the inner diameter of the wheel's mounting flange and the diameter of the shaft. This should provide a nice snug press fit between the two parts and keep the wheel centered.
Note: If you don't have a 3D printer, you can use a service like Shapeways or iMaterialise
Step 14: Mount the Bar
Step 15: Countersink
Step 16: Insert Bolts
If it is not deep enough, drill down farther.
Step 17: Vacuum Bag
Anyhow, first I applied glue. Next I inserted 1" bolts into a couple of the peg holes for registration, lined up all of the holes, and stuck the two surfaces together. Finally, I slid two 3/4" spacers onto the bolts on the back to increase surface area and keep the protrusions from puncturing the bag.
I slid the whole assembly face-down into the vacuum bag, sealed it up and fired up the system.
Step 18: Undo
Step 19: Mount the Flange
Note: In the pictured version, I am using a 5" base Kee Klamp. I found the Kee Klamps are not designed for rotation and the whole assembly was built slightly off center. This kind of gave the wheel a wobble. I ultimately ended up milling a precision fitting out of aluminum. However, if you do not have access to that, the initial pictured flange should work for you.
Step 20: Attach the Wheel
Step 21: Clacker and Pegs
Insert the pegs into the mounting holes around the diameter of the wheel and fasten them in place using lock nuts.
Step 22: Pulley
Using a 1/8" drill bit, drill vertically down through the center of the pulley's channel and through both side of the metal tubing.
Step 23: Mount the Motor
Insert the shaft of the motor from the inside of the pedestal outward through the motor shaft hole.
Mount the motor in place using bolts and 1" spacers.
Step 24: Pulleys
3D print the larger pulley for the clutch and press fit it onto the shaft of the clutch.
Pull the round tube onto the pulleys.
Step 25: Mount the Wedges
They were then printed on adhesive vinyl and applied to the wheel.
You could also print them on paper at your local copyshop and glue them down.
Step 26: Glue Supports
Step 27: Start the Circuit
Step 28: Connector Cables
Attach a quick connect to the end of a 12" red wire.
Attach quick connects to the end of another red and another black wire. Using a wire nut, twist these two together with yet another red wire to make a 3-wire set.
Step 29: Attach Cables
Step 30: Real Time Clock
Step 31: Power Jack
Solder the red wire to the Vin pin of the voltage regulator and the black wire to ground.
Step 32: Snubber Diodes
Step 33: 'Spin Again' Switch
Solder a green wire and 10K resistor to the other lug.
Solder a black wire to the opposite side of the 10K resistor.
Step 34: Program
Next, upload the following code to the Arduino:
Step 35: Assemble the Electronics Panel
Plug the switch and the appropriate PCB wires into the Arduino.
Also connect, the relay coils to the appropriate connector wires from the PCB.
Step 36: Wire the Clutch
Step 37: Wire the Motor
Solder a 6" red wire with a quick connect attached on the end to the other motor cable.
Step 38: Wire the Batteries
Take the red and black quick connect wires that are soldered to a single motor connections, and then connect the red quick connect to the positive terminal on one battery and the black wire to the negative terminal on the other battery.
Connect one of the quick connects from the clutch to the remaining positive terminal.
Connect one of the black quick connect wires from the group of three ground (black) wires.
Step 39: Insert Batteries
Step 40: Connect Together
Clean up all of the wires with zip ties after all of the connections are made.