II . MAKING THE PLEXIGLASS BASE
Its come time to make the plexiglass base. Truthfully it can be any material - but I recommend plexiglass or HDPE plastic.Download this file into Google SketchUp , and print it out to scale. Follow these instructions on printing out to scale using SketchUp. Now print out the picture below . The picture below shows what each hole will be used for , as well as showing what diameter drill bit you should be using. The drill bit size is located in the respective boxes. Be careful when cutting the template though.
Some info on using a jigsaw ( thanks GariWilson for finding it )
III. ADDING ON LOCOMOTIVE POWER
You will need the following components :
Two HS-425BB servos (BUY NOW)
Four Universal Servo Mounts (BUY NOW )
Eight 3/8" #4 Screws (BUY NOW)
Four 1/2" #4 Screws (BUY NOW)
Two 2.5" Wheels (BUY NOW)
Ball Casters Kit (BUY NOW)
1. First modify both of the servos as shown in this tutorial .In the tutorial where it says to center the servo the code in PICBASIC is .
PULSOUT (location ), 150 . For example
Start: ' Start Label
PULSOUT PORTB.4 , 150 ' Send a pulse to the servo
PAUSE 18 ' Pause 18 milliseconds
Goto Start 'Make a loop of it
. Please note this is at 4 mhz , for 8 mhz the resolution would be doubled to 300.
2. Now mount a universal mount to each side of both servos using the 3/8" #4 screws.
3. Print out this drilling template and drill holes where it shows . Use a 1/4" bit on the drill.
Notice how the servos fit perfectly on the template I made , yes thats the magic of CAD( Computer Aided Design) .
Now with the servos:
4. Attach the 90 degree servo mount to the servo using the 3/8" #4 screws . Now mount the servos using the 1/2" #4 screws. The screw should go through the plexiglass hole and into the hole of the servo mount.
5. Congrats the servos are mounted
6. Now mount the red servo horn that comes with each servo to a wheel. This can be done two ways. One way is to use hotglue to mount the servo horn to the wheel. Another method which is much cleaner is to use screws to fasten the horn to the wheel. Both methods are pictured below.
7. Now mount the wheel to the servo using the screw that came with the servo.
6. Now its time to mount the casters . Assemble your casters using the instructions in the kit. Keep the screws left over , you should have something like this remaining when you are done.
7. Mount one of the casters using two of the screws that came with them into the plexiglass.
8. Repeat step seven for the other caster . There should be 2 screws and 2 nuts left over .Keep them since we will be using them later . You should now have a plexiglass base that looks like this :