One of the biggest problems with trying to do something like the Hodgson Radial here in China is finding quality materials. I’ve been lucky with my aluminum products since there is a big Alcoa plant in Kunshan not far from where I live that supplies materials for both the China and worldwide aerospace market. Unfortunately I’ve not been as lucky finding a supplier of quality ferrous materials, and the purported 12L14 material I procured for my cylinders is a case in point. While I was assured this material was “equivalent” to 12L14, it was very gummy to machine and did not act at all like a free-machining leaded steel.
I turned a soft expanding collet to 0.997″ in the lathe. I did this instead of making tool C5 because it allowed access to perform end operations, such as the piston ring chamfer, on the blanks where the nut on tool C5 would have prevented this.
It should be noted here that when using expanding collets, or regular collapsing collets, to run multiple parts, it’s important to keep the diameters on the parts consistent. Any variation in the clamping diameter from part to part causes the collet to pull in different amounts. So, in order to keep length variations in check when doing facing operations like this, you need to have consistent diameters.
Next I’m turning the 0.656″ long cylinder skirt. The finish diameter of this portion is important so that the finished cylinders will fit properly in the crankcase. Since I have not made my crankcase yet, the actual size is not critical, but it is important to maintain the same diameter on all of the cylinders.
With a 3mm wide insert tool designed for both grooving and profiling, I began to rough out the fin area by plunging to a little over the finish diameter of 1.375″, stepping over 2.5mm and plunging again.
The same procedure used for the fin OD is employed again to turn the recess between the fins and skirt. You can see from the poor surface finish how gummy this material was. This is going to take a lot of polishing work to correct later on.
The beauty of using inserts here was that if I broke a tool, I could grind another insert and slap it on without affecting my setup.
Just past halfway on this set of fins. By this point, I was pretty sure this was not free-machining leaded steel, so I was very concerned with plunging these 0.032″ grooves 0.125″ deep into this mystery material.
Copious quantities of flood coolant kept everything turning smoothly so that one insert was enough to finish all 12 cylinders I was working on.
The lathe bed was protected with shop towels, and the part was lapped by hand. With the lathe running at 600rpm, it took about 20 minutes and 3-4 charges to lap each cylinder to size. All of the cylinders were lapped to 1.0000″±0.0002″.
- Fit to heads
- Drill aprons
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All material, including the CAD drawings, relating to the construction of the Hodgson Radial presented on this site is free to use any way you see fit. However, no guarantees are made regarding the accuracy or correctness of the material presented here.