More engineering - started a new part.

I did some work on the cylinder heads today, and drilled and counter bored the ports for the inlet and exhaust. They're finished now, apart from the holes for the rocker shaft. Check out the pictures:-

Cylinder heads very nearly finished

I started the gearbox, not much done yet, just the flange face, location diameter, bore for the bearing, and clearance drilling for the primary gear.

Gearbox started

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.

I went flying today.

The weather this week has been appalling with heavy rain and gale force winds at times. Today, it was superbe with sunshine and light cloud and light winds. A day not to be missed. Tomorrow is forecast to be back to heavy rain and gale force winds.



Jamies Bobcat now fitted with larger Jetcat P80se

The Front Housing and some assembly

Well, just enough to see if it fits. I made the Front Housing and fitted the crankshaft and conrods together in the crank case. 'Tis at this point I've discovered I need to remove a very small amount of material from the bottom of the sleeves because they foul on the crankshaft. Oh! well I can't see it making any difference to performance other than it just makes the engine that little bit lighter. Every little helps.

Here's some pix:-

Front Housing in the lathe for final machining

Note how its bolted to the mandrell

The rear end view

Assembled (temporarily)

Next will be the gudgeon pins and the PTFE end pads to prevent the gudgeon pins from scoring the bores. Then I can get the pistons moving.