Step 1: Gather the Materials
Corel Draw ("free" versions are sufficient)
VEX PIC Microcontroller
VEX 75 MHz Transmitter and Receiver
.2 inch Wood Sheet
.19 inch Foam Board
1/8 inch Wooden Dowels (skewers work nicely)
1/4 inch Wooden Dowels
Hot Glue (or other adhesive)
4 VEX 2-Wire 393 Motors
Assorted VEX Components
Axles (3" x4)
Delrin Bearing Flats (x4)
Lock Bars (x4)
Pliers/wire cutters/standard cutting utensils
Epilog LEGEND Laser Engraver
Xbox 360 Controller
Common Sense (recommended)
Step 2: Design
Step 3: It's Cutting Time
Open a New Corel document with dimensions 32"x20" (wxh). Drag and drop the first file into the document, click okay when prompted, and position the piece somewhere near the top left corner. Select the geometry, right click, and select properties. Change the Line Weight to Hairline and the Color to Red: this lets the laser know it's supposed to cut these lines, not engrave them.
Place the cutting medium into the laser cutter. The base, front, and sides should be cut from foam core; all other parts should be wood.
Click print, and adjust the print settings according to the following:
Wood: Speed 10%, Power 90%, Frequency 3500Hz;
Foam: Speed 70%, Power 60%, Frequency 2500Hz;
Make sure to change the paper size in Print Settings to match the document, otherwise none of the part will print -- even if some of it resides in the 8.5"x11" default.
Run the job on the cutter. Regardless of the material, each job should be run at least twice.
Rinse and repeat until all parts are cut out.
NOTE: As time goes by -- and the laser's tube heats up -- more and more passes may be required to cut through. If the laser starts dying, walk away for ten minutes or so to allow it to cool. It's recommended that you run the larger parts as several individual jobs, splitting them apart in Corel (right click, ungroup, and delete some of the geometry). Run the more complicated aspects of the parts first -- i.e. the wood connectors -- to ensure the more crucial parts get cut cleanly; straight lines that don't cut all the way through can be "persuaded" with a razor or other sharp object.
You need to cut out the following:
4 Bases (foam)
4 Sides (foam)
4 Fronts (foam)
24 Wheels (foam; 12 with round axle holes, 12 with square)
8 1.5" Gears (wood; 4 with round axle holes, 4 with square)
4 2" Gears (wood)
2 Short Cross Bars (wood)
2 Long Cross Bars (wood)
2 Inner Axle Supports (wood)
2 Outer Axle Supports (wood)
1 Centre Support (wood)
4 Axle Holders (wood)
4 Axle Holder Inner Caps (wood)
4 Axle Holder Outer Caps (wood)
Step 4: Assembly: Part 1
4 VEX Axles (or equivalent .125" square bar)
.25" Diameter Wooden Dowels
.125" Diameter Wooden Dowels/Skewers
4 VEX 2-Wire 393 Motors
4 VEX Flat Delrin Bearings
4 VEX Lock Bars
First, take two of the base pieces and glue them together, ensuring they're lined up fairly well (only worry about gluing around the edges; it's more important to secure the connectors than the center).
Then, take two of the front pieces (the shorter of the foam walls) and glue them together, making sure to line them up as well. Do the same with the other two fronts.
Now, carefully fit the base's pegs into the slots on the walls as shown in the last picture. Be sure not to put too much pressure on any one point on the walls; if it isn't going on, wiggle it around, but don't force it: it's designed to fit snugly.
DO NOT fit the sides on at this time.
Step 5: Assembly: Part 2
Now it's time to insert all the wooden interior supports to ensure the robot doesn't just fall apart under its own weight.
First, take the two Inner Axle Supports and fit them in to the inner pair of slots in the front. Slide them all the way through until they go into the corresponding slot on the opposite side.
Then, take the Outer Axle Supports and do the same thing, this time with the two outermost holes. The final central pocket is for the Centre Support; slide that one in last. Ensure all 5 supports are lined up with one another: their slots should be in roughly the same place, and looking perpendicular to the supports you should be able to see all the way through the ones on the end.
Next, take the two Long Cross Bars and line their slots up with the endmost ones on the supports. Push the Cross bars down, interlocking the slots. As with the base, don't force anything; if it isn't going, try repositioning it and trying again. Push each slot only a little at a time to prevent chipping or breaking. The bars should fit snugly into the slots, and they should end up roughly flush with the top of the supports.
Now, find the two shorter Cross Bars; fit these into the innermost slots on the supports, following the same procedure as before. These should also end up flush.
Step 6: Assembly: Part 3
For each of the four Direct-Drive wheels, you'll need the following:
3 Wheels w/ Square Hole
1 1.5" Gear w/ Square Hole
1 Axle Holder
1 VEX Lock Bar
Inner and Outer Axle Holder Caps
VEX Square Axle (or equivalent .125" Square Bar)
Hot Glue or other adhesive
Something sharp (like clippers)
First thing's first. Take the three wheels and stick the VEX Axle through them. This lines up the .125" holes for the dowels. Take 4 dowels and stick them through the holes in the wheel. Lay the wheel stack flat on the table with the dowels sticking up. Trim them so that they stick up between 1" and 1.5".
Turn the wheel over and put a thin layer of hot glue over each of the axle holes; this is more to keep them from sliding out than it is to secure them (since the whole purpose of the dowels is to support against torsion, it really doesn't matter how much they slide around, so long as they don't fall out).
Turn it back and line the Gear up with the dowels. Slide it down all the way until it touches the uppermost wheel. Slide the Outer Axle Holder Cap (the one with more holes) down in the same manner. Now, pushing down on the assembly firmly, trim the dowels as closely to the Cap as possible; then, hot glue them in place with a thin layer like the other side.
Next, take 4 more dowels. Put a small amount of hot glue in each of the outer holes on the Cap (the one's without dowels in them already), then place the dowels in the holes and push down firmly -- the Gear prevents them from coming out of the other side, so don't worry about that.
Take the Axle Holder and slide it down the newly-attached dowels, but don't glue it. Take one of the VEX Lock Bars and fit it into the holder, sliding an axle through it: this ensures everything's lined up correctly. Leave the lock bar in the slot.
Take the Inner Axle Holder Cap and slide it down the dowels; push firmly on it, trim the dowels, and hot glue them like before.
That constitutes one of the direct-drive wheels for the Bot. Now make 3 more.
Step 7: Assembly: Part 4
For each of the four Gear-Driven Wheels, you will need the following:
3 Wheels w/ Round Holes
.125" Wooden Dowels
.25" Wooden Dowels
1.5" Gear w/ Round Hole
First, take one of the wheels and fit a .125" dowel through one of the smaller holes; fit the other two wheels onto the same dowel in the same manner. Then, slide the other 3 dowels into the holes in the newly-made stack. Lay it flat on the table so the dowels stick up. Trim them so they stick up about 1" in length.
Turn the wheel stack over and apply hot glue to the dowel holes like you did with the Direct-Drive Wheels.
Take the Gear and line it up with the dowels; then, slide it down so it touches the wheel. Push firmly on the stack, trim the dowels closely, and hot glue them as before.
This constitutes one of the Gear-Driven wheels for the robot. Make 3 more before moving on.
Step 8: Assembly: Part 5
For each of the eight wheels (both Direct-Driven and Gear-Driven), cut a strip of Non-Slip Pad approximately .5" wide and 1.25" long. Place a small dab of hot glue on the side of the wheel stack and push the end of the strip down on it; you may want to use a tool to do this to avoid being burned by the hot glue.
Apply more hot glue at quarter-wheel intervals, pushing the strip down like before. Trim the end so it sits flush with the other, and then glue it down. Apply a small dab of glue to seal the two together. Then, take a pair of scissors and carefully trim away any of the Pad hanging over the edge on either side -- it will interfere with the gear on one side and the wheel's rotation on the other.
Repeat for all eight wheels.
Step 9: Assembly: Part 6
Take the four Gear-Driven Wheels. Cut four axles from the dowel, 2"-3" in length (long enough to pass through both Axle Supports with about .25" clearance on either side). Line up the wheels within the base's pocket; you may want to prop the base up on something in order to make lining the wheels up easier.
Slide a dowel through the Axle Supports and through the wheel. It should spin freely in the Supports. If it doesn't, take a .25" drill bit and wiggle it around in the Support holes to widen them slightly.
Turn the robot on it's side and apply hot glue to the place where the Wheel Assembly and the Axle meet, on the inner side of the Robot; once dry, place a tiny dab of hot glue on either end of the axle (this is to prevent it from sliding out during operation).
Repeat this with each of the four Gear-Driven Wheels.
Step 10: Assembly: Part 7
Take one of the VEX Delrin Bearings and fit it on to the outside of the Inner Axle Support (the side nearer to the hole in the base); take some VEX Screws and attach the Motor via the two holes in the Bearing (i.e. not the one the axle will pass through). Do the same thing with the other three motors. Make sure to tuck their cords in such a way that they don't put too much pressure on each other, as that could damage the connectors.
Now, take one Direct Drive Wheel Assembly and set it in front of the Motor where it should go, wooden components facing inward. Take a VEX Axle 3" long and run it through the Wheel Assembly and into the Motor. Secure the open end with a VEX Axle Collar. If necessary, cut the axle down to fit better (do this by marking it, then removing it and cutting it with a hacksaw). Repeat for the other three wheels.
NOTE: Depending on how much hot glue was used to secure the axles on the Holder Cap, the Wheel Assembly may fit a little too tightly to be able to spin freely with the motor. If that's the case, take a sharp object and cut away the part of the foam base that is restricting its movement.
Finally, take one of the 2" idler gears and cut a 3" length of .25" dowel. Slide the Gear onto the dowel and check it; it should rotate freely. If it doesn't, take a .25" Drill Bit and enlarge it as you did for the Axle Support Holes.
Next, slip the gear in between the gears of the Direct-Driven and Gear-Driven Wheel assemblies, making sure to interlock the teeth. If it doesn't go in, don't force it. Simply turn one of the gear assemblies to help maneuver it into place. Slide the dowel through, but don't glue it.
Try turning the Direct-Drive Wheel Assembly. The Idler Gear and other Wheel Assembly should turn as well. If they don't, turn each one individually to locate the problem; fix it by either widening holes or cutting away foam on the base.
Once everything spins correctly, apply hot glue to either end of the Idler gears' axles; they don't need to turn, so go nuts!
Your robot is built (more or less). The only remaining assembly is the attachment of the sides and base; don't do that quite yet though. You need to set up the VEX Microcontroller and make sure everything works before sealing it all up forever.
Step 11: Control
Attached are all the files for the Arduino code. Please note that you will have to rename the "adafruit-Adafruit-Motor-Shield-library-4bd21ca" and the "USB_Host_Shield_2.0-master" folders for it to work. If you wish to go this route for the bot, we wish you luck in overcoming the Arduino hardware limitations.
For the rest of you, proceed to the next step for instructions for the VEX Microcontroller.
NOTE: If you do, by some miracle, manage to make the Arduino compatible, we would greatly appreciate it if you would send us a copy; we'd be more than happy to credit you with the programming, and that way we can expand this Instructable.
Step 12: Coding
Take the VEX PIC Microcontroller and connect it to a Windows computer (Or computer running a Windows emulation) using the proper cable.
Download RobotC for VEX; it's a paid program, but all you need is the free trial.
Connect the VEX Microcontroller to your Computer's USB Port via the VEX Serial Adapter. Give it a moment to connect, then open RobotC. (You'll need to also connect the 7.4V VEX Battery to the Microcontroller.)
First you need to download the Master CPU firmware. This can be accessed from the Robot File Menu as shown in the screenshot. Then you'll need to install the RobotC firmware, located in the same place.
After resetting the Microcontroller's firmware, download the program below. Open it in RobotC; then click "Download Program" under the Robot File Menu. Power off the VEX Microcontroller, then disconnect it from the computer.
NOTE: It's extremely important to power off the Microcontroller before disconnecting it; it you don't, the program won't run correctly when you go to test it.
Step 13: Wiring & Electronics
Right Side: Ports 1 & 2
Left Side: Ports 3 & 4
That's it for the motor wiring for now; when you feel ready, move on and we'll test the Robot!
Step 14: Testing and Completion
Attach the 7.4V VEX Battery and Receiver to the appropriate slots on the bottom of the Microcontroller. Power up the Microcontroller and the Transmitter (the controller-looking thing); the VEX Microcontroller should have a green light on when connected to the Transmitter.
Now, just run the bot and see if the motors work as they should. If they do, kudos. If not, well, drat. Good thing you didn't seal it up.
Unplug motors individually to try and isolate the problem; once located, the problem could probably be fixed by widening holes or wiggling things a bit. If you still have trouble however, post a comment and we'll see what we can do.
Step 15: Final Assembly
If it's not, you missed a step.
Now it's finally time to seal up the robot.
Take the remaining pair of bases and glue them together like you did way back in Step 4. Take a Drill Bit and, using the Microcontroller as a guide, make holes corresponding to the screw holes of the Controller, Receiver, and battery tie in some sort of logical fashion on the top. Attach these components with screws.
Then, take a .5" Drill Bit and Drill two holes through the base; line them up so that they sit in about the same place as the empty space in the motor compartments.
NOTE: If you had to cut down the base's foam for the wheels to turn properly, you'll have to mirror those cuts on the top; do that before attaching it to the Front.
Now, carefully remove both of the Fronts from the base. Lay the top in place, resting it on the wooden supports. Pass the motor wires through the nearby holes in the top.
Now, we reattach the fronts. Slide it on carefully, lining it up with the bottom, top, and inner supports.
NOTE: This part can take a while; don't rush. The first side to be attached will be the hardest: after that, the other ones will be more lined up.
Take the other Front and attach it in the same way.
Once both fronts are on, do the same thing for the sides. Layer two thick (like in Step 4) and hot glue them together (also like in Step 4). Then, slide them on to the longer side of the base, aligning both the top and bottom with it's respective holes. Make sure the connectors on the end mesh up; if they hit, you have to flip the Side. Push until it sits roughly flush with the other connectors.
Now, take the motor wires (reattach the 2-3 Prong Converters if needed; it's a good idea to secure them with electrical tape) and connect them to the Microcontroller. Remember, the Right Side goes in ports 1 & 2 while the Left Side goes in ports 3 & 4. Tape them down to keep them secure. We added an antennae to ours to improve reception. All we did was stab a skewer through the bot in one of the empty compartments nearby the Receiver, clip the bottom, and hot glue it. All that's left not is to attach a battery and plug in the power and Receiver wires.
TA DA! You're robot is done!! Have fun driving it around all day and impressing your friends with your engineering prowess.
Just don't get it wet.
Or leave it in the sun.
Or fly it without a Primary Buffer Panel.
Consider yourself warned.