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5 Cylinder Rotary Engine - Part 2

Nigel Taylor

Having lost this engine for 2 years after moving house I remembered why it had been put away - a broken tap in the crankcase.

The offending broken tap. As you can see it is well buried and looks like I′ve already had a go at remving it

Not sure how well this will work, but I bought a solid carbide end mill.

The solid carbide mill did get the tap out, but the end mill came apart in the process.

As you can see in this picture I resorted to the trusted TiN HSS end mill and used this to finish the machining.

The TiN end mill was still in good condition at the end of the process.

The casing with an aluminium plug back in place of the broken tap.

I glued the aluminium plug in with some very thick instant glue.

With the tap removed and a piece of aluminium in it′s place I then drilled and tapped the 8BA threads to bolt the heads and cylinders down. This just gave me lots of trouble as the aluminium kept stripping. So I drilled the holes out to 3mm and then fitted steel inserts into the holes that had been tapped 8BA. This gave me a much more secure fixing.

The bolts looked too bulky so I machined the thread down to 1.4mm diameter in the centre section of the bolt.

The crankcase, cylinders, liners and heads are now all in place.

Part 1 - 5 Cylinder Rotary Engine

Part 3 - 5 Cylinder Rotary Engine

If you have made a similar engine and would like to share your experience we would love to hear from you - ed.