You built this? Where did you come by the design? I would love to make one too.
The design was mine but no plans. I just designed as I went along. There is one similar on utube. .... I believe. The trick is to machine it without the plate warping....moving from the stress or it will bind. I gave a friend with a surface grinder and that helped. The next trick is the thru shaft must be perfect with the bored hole in the base plate. I made some SPLIT cone shaped washers top and bottom for the shaft to ride in and the top plate to ride on.
Look at the way a commercially made one is built.