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.
Sawing the Shapes
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 Cut Knurling Tool
It seems like I’m always making a tool to make a tool to make a tool… Then again that’s why we all started with the hobby isn’t it? I finally have some time to get back on the Quorn project and it looks like I’ll be needing to knurl a few pieces. Fortunately, or unfortunately as my wife sees it, the “Home Shop Machinist” magazine recently ran a 5-part article on a cut-type knurling tool. The article started in the March/April 2010 issue and ran through Nov/Dec 2010. In this article Michael Ward describes a knurling tool that creates perfect, full-depth knurls without being hard on the lathe. It looks fabulous and if it works even half as well as described, all the better! Who could pass up an opportunity like that?