Updated 03/14/2005.
Safety first! Wear eye protection and never touch a powered robot!
Note: Do not use Loctite or thread locks on the assembly. They are not necessary and may cause damage to the Lexan.
Image of completed Right (robot's right) leg.
Using four of the nylon rivet fasteners, attach two of the "L" brackets as shown. Push the rivet fasteners in from the back (bottom of panel as shown).
4 x 
2 x 
Figure 1.
Clean the bottom of the servo near the wire with alcohol and allow it to dry. Then peel the green plaid cover off the tape on the hinge, and line the hinge up with the edge of the servo. Press the hinge onto the servo very firmly for a full ten seconds to insure a good bond.
1 x 
Figure 2.
Use four rivet fasteners to attach one servo as shown, pushing the fasteners in from the top. Make sure that the servo's mounting tabs are on top of the "L" bracket.
4 x
Figure 3.
Use five 4-40 x 1/4" hex socket head cap screws to attach the 1.0" nylon spacer bars. Make sure the one to the immediate left of the servo hole is aligned to the hole. This will ensure the vertical servo will fit properly in the next step.
5 x 
5 x 
Figure 4.
Drop the second servo in through the servo hole as shown. Use four rivet fasteners to hold it in place.
4 x
Figure 5.
To maintain compatibility with our program, the robot legs have to be mechanically aligned. To do this move the servo to its center of rotation using the Bot Board, SSC, or other servo controller or microcontroller. We have set up a tutorial to guide you through this step. If you are using a different microcontroller, consult your electronics documentation for help with this step.
Note, centering a servo simply requires generating a 1.5mS positive going pulse that repeats every 20mS.
Figure 6.
While the servo is centered, install the servo leg lever onto the servo horn. To make this step easier, drill the indicated holes with a 1/16" drill bit. Use two #2 x 1/4" Phillips head tapping screws and two washers. Use the servo horn holes as illustrated. The bottom edge of the lever and the bottom edge of the main panel should be parallel.
2 x 
2 x 
Figure 7.
Assemble the upper driven link as shown. It consists of the top link (with mounting tab), round Lexan spacer, and lower link. Use a 4-40 x 3/4" hex socket head cap screw and a 4-40 x 1/4" nylon acorn locking nut. The screw should go in from the top and the nut should be on the bottom.
1 x 
1 x 
Figure 8.
Attach two ball links as shown. Remember to make them face opposite directions! The ball on the servo lever should be facing down, and the ball on the upper link should be facing up.
2 x 
Figure 9.
This section will connect the two ball links from the previous step. Make the ball socket assembly (dog bone) as shown. The overall length of the dog bone should be exactly 1.75". Make sure that the ball sockets face opposite directions to match the ball links.
2 x 
1 x 
Figure 10.
Snap the dog bone onto the ball joints firmly.
Figure 11.
Attach the front panel using five of the 4-40 x 1/4" screws.
5 x
Figure 12.
Attach the lower link the same way you did the upper. Use a 4-40 x 3/4" hex socket head cap screw and a 4-40 x 1/4" nylon acorn locking nut.
1 x
1 x
Figure 13.
Now it's time to assemble the leg. Align the two leg pieces with the leg spacer (looks like a shortened leg piece) and use a 4-40 x 1/2" screw and acorn nut to hold it together. The screw should go in through the front, and the nut should be in the back.
1 x 
1 x
Figure 14.
Slide the robot foot rubber end cap onto the end of the leg. It might be a tight fit, but if you wiggle it, it will fit.
1 x 
Figure 15.
Attach the leg assembly to the linkage using two 4-40 x 3/4" screws and acorn nuts to hold it together. The screws should go in through the front, and the nuts should be in the back.
2 x
2 x
Figure 16.
The hardware associated with the leg pivots need to be adjusted. If it's too loose, the leg will be sloppy; it it's too tight, it will cause unnecessary friction. Carefully adjust each joint until you're happy with it.
You've now completed the robot's leg!
For a Hexapod, make two more like this one, and then make three that are mirror images of this one.
For a Quadrapod, make one more like this, and two that are mirror images of this one.
Figure 17.