Weather stopped flying (yesterday)...

...But it didn't stop me doing some work on the Ketro KT120fst engine. I've not been satisfied with the design of the crankshaft where two M3 grub screws hold it all together. So I've come up with a design modification that will beef up the strength and rigidity. I made two special screws from M4 cap head socket screws and I turned off a section of thread to form a 3.0mm dia. pin whilst leaving a threaded section intact. Then I drilled and reamered a 3.0mm hole through where the original M3 thread was in the crankshaft parts, followed by an M4 thread down to the center, and counter bored 6.0mm dia. to contain the screw head, which incidentally, I turned down to size. Now I have far more confidence in its integrity.

More integrity

You can see the screw head in one crank and the pin in the other. Unfortunately there is a little bit of run out along the length of the shaft, but I'm hoping the rear bearing set will contain it.

No flying today, poor weather conditions

The wind was blowing a hooley today, so I spent the day in the machine shop. Finished the finning on the cylinder heads, and now I'm thinking about the crank shaft design change. I have to enable the use of one piece conrods due to lack of clearance on the lower parts of the cylinders and the pistons. This will necessitate the design change from a one piece shaft to a three piece.