Building The B9 Robot Knees

knee hinge-painted-1.jpg (42796 bytes)

Building the Knees
	These are my knees. They are made of wood with a routed edge. I purchased the plans for the lower section of the robot from Bermuda Triangle Engineering. I deviated from the plans and went with the "stepped" look, where the center rib is the widest and they step smaller as they go up/down. I believe this is the way the real robot was.
	The plans say to coat them by hand with rubberized auto undercoating. I found it very difficult to spread the coating on the knees. Even after sanding I could not get a smooth surface. I decided to spray the coating directly on the knees and go with the slightly textured natural look. I really like how they turned out as they have more of a rubbery look and feel.
	Here's the rubber undercoating I used for the knees. I got it at Parts America.
	Here are the different parts of the hinge. The main part of the hinge is styrene plastic. The center is cut from a 1 inch PVC rod. The two washers are actually machine shims. In order to get a washer with such a large opening and thickness, I had to order machine "Arbor Shims" from McMaster-Carr.
	Here it is mounted to one of my knees. They are only painted with primer at this point and I only made one so far. Call it a prototype. I wanted to see how it would turn out before doing the rest. I only hope the rest come out this good.
	I finally took a picture of the painted hinge. They came out pretty good. I made four of them
	I added brackets like this one to the inside of my knees. They anchor them to the tread section. I chose wing nuts so that tools are not needed to put everything together.
	The left knee has two brackets attached to the outer, inside edge. The wing nuts screw into threaded inserts that are on the upper rail of the tread section.
	The inner, inside edge of the knee has a single bracket. I placed it dead center. Besides provided a solid platform for the legs and everything above, the brackets align the knees evenly so the legs will set down on the threaded rod at each end of the knee.

Building the Knees