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.
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Step 1: Go Get Stuff
You will need:
(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
Having access to a 400W metabeam laser cutter, I was able to cut out the following files quickly and easily out of 3/4" plywood.
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
Press fit a 1/2" x 3" tube onto the shaft of the geared DC car seat (or wiper) motor.
Step 4: Mount the Clutch
Place the back piece of the pedestal horizontal on two sawhorses (this is the side with the motor mounting holes).
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
Loosely bolt the clutch to each side of the pedestal.
Step 6: Fasten
Drill two pilot holes in each of the corners to attach the corner brackets squarely to the pedestal front and back pieces.
Fasten them together with wood screws.
Step 7: Measure and Mark
Measure 3" in from the edge parallel to the center slots and draw a line.
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)
I only had 2" and 2-1/2" wood screws on hand, and needed to use 2-1/4" screws to mount the casters, 2x4, and base plate together. I ended up needing to use 1/4" plywood spacers for each of the casters so that I could use 2-1/2" screws without having them poke through the top of the base plate.
Basically, cut the spacers using the attached template, place the casters atop each one, and trace the mounting holes.
Step 9: Drill and Fasten
Place the spacer (or caster) on the corner of each 2 x 4 and use the caster's mounting holes as a guide for drilling pilot holes.
Once all of the holes are drilled, mount all of the caster in place using wood screws.
Step 10: Attach the Bottom Plate
Cut the bottom plate out of 3/4" plywood using the attached template if you have not done so already.
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
Attach the pedestal to the base by inserting the tabs at the bottom of the pedestal into the slots on the top side of the base.
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
Use the spacer for the metal to mark and drill two mounting holes in the 1" aluminum bar.
Drill a 5/8" mounting hole 1" from the opposite end of the aluminum bar.
Step 13: Fasten and Press Fit
Now is time to insert and tighten all of the bolts holding the clutch in place.
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
Bolt the bar to the top of the pedestal using two stacked 3/4" spacers.
Step 15: Countersink
Use a drill with a 3/4" spade bit to widen the wheel's center mounting holes to a depth of about a 1/4". It should be drilled deep enough to countersink the carriage bolts.
Step 16: Insert Bolts
Insert the carriage bolts and make sure that the top of the bolts are lower than the wheel's surface.
If it is not deep enough, drill down farther.
Step 17: Vacuum Bag
Having access to a very large vacuum bag system, I decided to use that to glue the top of the wheel to the bottom of the wheel. Barring that, You can glue and clamp or place another sheet of plywood on top and a lot of weight, like a bunch of cinder blocks (or a combination of the two).
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
Take the spacers off the back of the wheel and remove all of the clamping hardware.
Step 19: Mount the Flange
Mount the flange onto the back of the wheel.
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
Slide the wheel onto the shaft of the clutch and fasten it in place with the lock nut.
Step 21: Clacker and Pegs
Attach the clacker to the top of the 1" bar.
Insert the pegs into the mounting holes around the diameter of the wheel and fasten them in place using lock nuts.
Step 22: Pulley
Press the nylon pulley onto the end of the motor shaft.
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
Pull the nylon gear off o the motor shaft if you have not done so already.
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
Press the nylon pulley back onto the motor shaft and insert a 4-40 x 2" bolt down into the 1/8" hole to hold everything in place.
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
Each of the wedges was designed by a coworker of mine using the attached template.
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
Apply glue to each of the electronics panel supports and clamp them in place about 1/4" below the upper edge of the lower corner brackets on the inside of the pedestal.
Step 27: Start the Circuit
Start to assemble the circuit as specified in the schematic, focusing on the parts that can be soldered to the PCB.
Step 28: Connector Cables
Attach quick connects to the end of three black wires and connect them together with a wire nut.
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
Attach the connector cables for the relays to the transistors on the circuit board as specified in the schematic.
Step 30: Real Time Clock
Assemble the real time clock circuit and and add it the circuit board as outlined in the schematic.
Step 31: Power Jack
Wire a power jack such that a red wire is attached to the center terminal and a black wire is attached to the terminal electrically continuous with the inner barrel.
Solder the red wire to the Vin pin of the voltage regulator and the black wire to ground.
Step 32: Snubber Diodes
Solder snubber diodes between each of the parallel sets of pins on the relays.
Step 33: 'Spin Again' Switch
Solder a red solid core wire to one of the switch's terminal lugs.
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
First you will need to initialize the real time clock. You can do this by following the instructions on this page.
Next, upload the following code to the Arduino:
Step 35: Assemble the Electronics Panel
Mount the Arduino, relays, PCB, switch and power socket to 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
Attach the two long red quick connect wires to the cables coming out of the magnetic clutch and insulate them with shrink tube or electrical tape.
Step 37: Wire the Motor
Solder the bare red wire from the grouping of wires with the red and black quick connect terminals to one of the motor cables.
Solder a 6" red wire with a quick connect attached on the end to the other motor cable.
Step 38: Wire the Batteries
Place the two 12V batteries side-by-side.
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
Place the batteries inside the base of the pedestal.
Step 40: Connect Together
Connect the motor, clutch and batteries to the relays as specified in the schematic.
Clean up all of the wires with zip ties after all of the connections are made.
Step 41: Case Closed
Place the electronics panel face down on the inside of the pedestal to hide the electronics and finish things up.
Step 42: Lunch
Let the wheel decide your lunch and prosper!