1/4″ hardwood (plywood) board cut into 12″ squares
1/16″ x 1′ x 3′ Aluminum Angle (cut into 1 ft lengths)
1/4″-20X12″ Threaded rod (4 pieces)
1″x2″x12″ wood (2 pieces)
Closet Door Ball Catch (Solid Brass Co N-7287 or Similar) (x2)
2 Motors (see http://blog.dankohn.info/?p=694)
10-24 machine screws (for mounting motor)
Nuts and Washers for #20 rod (above)
* – All items above purchased a Home Depot except were noted. They should also be available from LOWES or any good hardware store.
I am NOT a woodworker or mechanically inclined, if you are you will probably want to measure everything and drill one piece at a time. If you are like me I would suggest you stack the two 1/4″ plywood pieces, the Aluminum Angle and the 1″x2″ and drill them all at once, then put a threaded rod though the hole and move to the next hole to be drilled (see below):
Next, drill the bottom piece of plywood for the Closet Door Ball Catch which are used as front and back casters. I drilled a 13/16″ hole 2 inches from the front and back centered on the plywood board.
You will need to adjust the spring tension on the ball so it will act like a caster. This can be done by turning the white plastic on the back. The height can be adjusted by turning the entire assembly in its mounting bracket. You want it so the robot’s motorized drive wheels make good contact, but the robot does not teeter when starting or stopping.
Then you will need to mark and drill the Aluminum Angle for the two holes needed to mount the motors. I suggest using making tape on the motors, then mark the holes and the center of the drive shaft on the tape, then put the tape on the Aluminum Angle, making sure the drive shaft center is at the 6″ mark on the Aluminum Angle, and drill.
You can transfer the holes to the second Aluminum Angle by placing the two back to back and using the already drilled piece as a guide.
Once it is all drilled, start with the the bottom placing the bottom plywood, Aluminum angle and then the 1″x2″ board down. Put a nut, lockwasher and washer on the threaded rod, put though the 1″x2″ board, Aluminum angle and the plywood then secure with a washer, lockwasher and nut. Do this on all 4 corners. Then do the same for the top plywood.
(note, lock washers NOT shown here)
The final robot will look like:
This base (and two more just like it) were built for use in my Computer Interfacing class at the University of Memphis. I plan to use an H-Bridge circuit, 68HC11 development board (FOX-11), and add Sonar, Line Track, IR Distance and other sensors to the robot for various assignments in the class.
For more pictures goto http://dankohn.info/Class_Bot/
PS Thanks to Wesley Harris for doing most of the assembly of the bots!