Servo - October 2010

FIGURE 3

FIGURE 4

FIGURE 5

the 1/16” piece, I’ve found the best method is to bolt down a board, then use wood screws to clamp down the piece.

I proceeded to drill out holes for frame rails and for the brushless motor mount (Figure 3). Because the front of the robot is going to be receiving the most amount of abuse, I decided that four bolts per each frame rail would be significant support. I also drilled a large 1-1/8” hole in the top of the 1/32” plate for the brushless motor.

Now that the base plates were finished, my next step was to cut out some frame rails. I planned to make the entire frame of the robot 3/4” high, so all I had to do was set up the table saw and rip a piece of 1/4” UHMW (Figure 4). I then took that piece to my cutoff saw and cut two 2-1/2” long pieces and two 3-1/4” long pieces (Figure 5).

With the pieces the proper length, I needed to create the proper angles for the front pieces. In order to do this, I again set up the mill, I measured the angles, clamped the pieces in, and ran a 3/8” end mill over the end (Figure 6). The last major step before I drilled out the rails and mounted them was to create slots to mount the motors. I set up the mill again and proceeded to mill a 3/4” slot 1/8” deep into the UHMW.

I marked everything out and used a center to create a pilot. I then drilled out all the mount holes to 7/64” to later be tapped out for a 6-32 machine screw. I also drilled out the holes to mount the drive motors (Figure 7). I then went back and ripped out a 1/8” piece of poly and drilled it out. Things were really starting to come together (Figure 8), but there was one setback. I put everything on the scale and it was over weight. So, I had to change a few things about the design.