The treadle pedal was made from pine scraps I had in the garage. It is just four 1-by-2s lapped together and screwed from the underside for reinforcement. I included a diagonal strut from the front right to back left but it still feels weak when treadled from the right. A second strut in the opposite diagonal might have to be added later. The treadle is attached to the back of the lathe frame using two small door hinges.
The treadle effectively adds weight to one end of the wheel when attached. I looked at where the wheel’s heaviest side was (the part that wanted to rotate towards the bottom) and attached the ‘connecting spacer’ (that connects to the tie rod) on the opposite side of the wheel. That way the treadle is the first stage of balancing rather that just a further complication.
A wooden crank connects the treadle to the wheel via two 3/8 lag-screws with washers. A spacer block of wood allows the crank to pass over the stop collar on the wheel. The spacer is rectangular in a radial orientation so that I could reposition the lag-screw in the future if I wanted to change the mechanical action of the treadle (an idea I liked from WoodChux – more lathe literature!).