Building the 1/4-Scale 5 HP Red Wing: Part III

| January 2005


Editor's note: This is the third installment in a planned four-part series on building the scale Red Wing engine.

Hello again! If you caught last month's article, you will remember that we covered milling of the large pieces. This month I want to expose you to some of the smaller and more difficult pieces to work with.

Step 9: Preparing the Crankshaft

The crankshaft is an interesting place to start. I had never made one before, but I was sure it would be a piece of cake. The crankshaft is made of 1/2-inch round material. The throw is 1-inch long and made of 3/8-by-5/8-inch flat stock. The throw shaft is 7/16-inch (0.437") round material.

The instructions call for silver-soldering the pieces together. I chose to braze the pieces and it worked very well. Here is a tip for those that haven't thought of it: The 1/2-inch crankshaft can be left in one long piece. The throw pieces are slid into place and everything is brazed. After cooling, the section of the main shaft that is not supposed to be there can be cut and removed. Leaving the main shaft whole helps to insure the finished crankshaft is straight.

The keyway can be cut one of two ways. You can use a 1/8-inch (0.125") end mill or a woodruff cutter like I did (Photo 1). Either way will give good results as long as the crankshaft is clamped in place securely.

Step 10: Completion of the Fuel Tank and Working on Small Parts

In the first article I talked about turning the bottom of the engine frame into the fuel tank. I milled a 1/8-inch recess at that time. Now is as good a time as any to finish the tank.