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The case is now on the fixture mounted on the circular table and the fins are being machined. The tool is specially made for this engine to get the correct radius. Note it worked best when climb milling and all the slots were cut to depth in a single cut. This gave the best finish and the least chatter. Another trick Brian has used is to fit the dummy backplate fixture to the case to give even more stiffness to the case whilst machining. |
Machining the transfer port. This is the tool that Brian used - a single point tool with the largest shank that will allow the radius required for the internal port. |
The outside of the case below the exhaust port is now machined. | The conrod clearance groove has been machined by rotating the case and using another Brian's custom tools. |
The case is now finished and any of the little hand fettled areas where machining is impossible have been dremel'd. |
This is the machining of the 2 fixtures needed for machining the crank pin. There are two fixtures as the shaft mounting holes are different sizes. One is used for the machining when the shaft is plus 0.3mm and one for when the shaft is at the final size. The two are made from a single piece of aluminium and parted off when finished thus ensuring that the offsets are identical. |
The shaft is set up in the lathe for the final grinding to final size. The power is a Dremel driving a custom made toolpost grinder. |
This is the centre pin in the chuck used for mounting the shaft turned to allow the driving dog to clamp on it and the crankpin. |