We use a hardened acme threaded rod to stretch the stirrups. As the leather is stretched, our stretchers are also twisted 30-degrees past 90-degrees. The pegs at the bottom for the stirrups go around, are tilted foward 15-degrees causing the thead of the stirrup to hang parallel to the bottom of your fool, as you sit in the saddle. This releaves strain on the riders ankles and knees.
The block for the top of the stirrup has been kept wide and round so as not to set the break in the stirrup leather where it would go over the bar of the tree.
Advantages of the stretcher is it doesn’t tie up the draw down and its small enough to hang on the wall out of the way.