Starting Work in the Shop
The first stop in the machine shop for all projects is cutting the stock. Here I’m squaring up a piece of hot-rolled mild-steel round stock in the band saw to make the ball turner body. The cant being removed in this photo will be further sawn to make the rotation stops.
There are times in the machine shop when you need to make a spherical ball out of metal. You can form grind a tool and plunge the sphere on the lathe, or like Reed Streifthau of the Quorn Owners Yahoo Group, you could use an inexpensive import boring head to make a ball turner. Starting from Reed’s design, this page attempts to document what I came up with.
Dry fit all the pieces and make sure each of the hone bodies opens and closes smoothly with no drag or catching. Any sloppiness in the hinge will affect the hone’s ability to hold close tolerances.
Sawing the Shapes
To make the sawing operation a little easier, I printed out copies of my stock plan and glued them to the stock.
The blocks are then split at the bandsaw. Don’t remove any of the waste at this point. We’ll use the orthogonal surfaces for location in future operations.
Since most of the work on these hones will be in the fixturing and setup, it makes sense to machine more than one hone while you are at it. Each of these three 7075-T6 aluminum blocks will make both halves of one frame for a total of three hones.
As I was working on my Hodgson Radial, I needed to accurately size the crank journals, but I didn’t want to risk tapering the ends as usually happens when polishing with sandpaper. So I made myself a set of external hones (photo of my set on the left), based on a set that I remembered seeing on Ron’s Model Engineering and Model IC Engines website interestingly named the Nikapena Hone.
The beginning of the second week, the Advanced course. This course really tested my trig skills. Truth be told, only two people in the class had a really good understanding of the trig needed for this week, myself and one high school kid attending the class! All I can say is what a lucky kid to be able to partake in something like this.