Here is my latest project, a Skelerector (summer/fall 2006).

A big thanks to Brad Fraley and his
BooPack Software
This software allowed me to design the 4-bar linkage pretty much exactly how I wanted it after I
changed my mind several times.  But, the dimensions worked as predicted each time too and that is
the most important part.

Directly below is the .bar file I used for designing my skelerector.  Feel free to download it and play
with it for your needs.  These dimensions were specifically tailored for the Menards skeleton.
An important item shown by the arrow is having the
forward/upper (point 2 from diagram above) horizontal
piece to have its pivoting at the ends with the torso bar
welded to it then.

I welded a couple small pieces just below the pivoting area
so I could zip tie the upper leg bone onto.
In my own personal design, I vertically offset the 4-bar system to
allow the lower leg bone to be in line with the foot flat on the ground.

This is also allowing me to try a more "off the wall" air cylinder
connection setup than what I have seen done by others.

Yes, I like to do things differently.  What fun and less frustration
would it be iif just copying a tried and true method.  :-)
Onto Page 2 for some higher res pics
To Video Page
How-To Pages
The main dimensions needed for the
design are:

Shown in the Set Size table are the
dimensions (well rounded some) for
the skelerector I built.
Skelerector Home Page
Added Arm Action