In another section of The Hobbyist's Machine Shop I am building a 3/4 inch scale locomotive designed by Kozo Hiraoka. The Locomotive is the Pennsylvania Railroad A3 Switcher. Kozo recommends a centering tool be made to help in accurately alining parts in the four jaw chuck. The drawings for this tool can be found in Kozo's book, Building the Shay page 150. I have modified the design slightly, but these photos will show how I made mine.
Kozo's design used only one brass insert with the ball seated against the steel holder. With mine, I can install the "close" end in either direction, whatever works best. In fact in these pictures, my pivot ball is installed closer to the work while Kozo shows his wiggler built the other way around. After testing, I think it doesn't makes any difference. I just needed enough clearance in the holes so the rod would "wiggle". |
This is the back side on my wiggler. I have bored a 60 degree angle into this end of the smaller fitting. |
This is my "front" side of my tool and the ball is located just behind the hole where the rod emerges. |
This will give you and idea of how much angle can be obtained with my setup. Of course you do not use the tool until you have your part already centered close by eye. So this amount of movement on the short end should be plenty! I'll have some pictures of this tool in action when I use it in the Pennsy A3 project. |
I spent some time making the tool look "pretty".