Twin Rotary Valve Engine

[PaulR]

Started another project while cogitating on the crank+eccentric uniflow idea, this one is a bit more straightforward: a twin single acting rotary valve engine with Scotch yokes driving the crank.

Made the cylinders from old towel rail tube and 5/8" brass square with mild steel pistons and temporary rods. Made the two valve blocks, the simple cranks and the flywheel. Need to find a piece of steel (or brass) the right size to make the long inboard cylinder support and a piece of sheet for the base.

[PaulR]

Made the yokes today. The vertical slide was bouncing around all over the place for some reason, maybe the slot drill is a bit worn or I just have the speed right? Anyway, the slots needed considerable attention with a file to bring them anything like straight. They're wider than planned so I'll just make the pins a bit fatter 

[PaulR]

Made the crank pins and washers and the inboard cylinder support - drilling the 1/2" holes for the cylinders was quite thrilling on the rickety old drill press but it came out alright even if my garage was full of burnt cutting oil fumes! Here are the bits placed together - the two copper air tubes will go through those holes in the middle down to the brass valve blocks. Man it's an ugly duckling and the blocks to guide the rods from the yoke have to be made yet.

[Sanjay F]

I think 'interesting' rather than ugly! Coming along nicely following along 

[PaulR]

I've been having a bit of a nightmare with this stage of the build. Soft soldering comparatively thick chunks of brass and steel to opposite ends of a very thin tube is tricky, every time one end was soldered the other parted company... and there are still some tubes to solder in place! In the end I desoldered everything so I could go the silver solder route instead. After lots of careful filing, emery cloth and cleaning I got rid of all the soft solder and the silver stuff went like a dream in comparison. I should be able to silver solder the other end without any issues and can then soft solder the tubes.

[Sanjay F]

Looking good, steady progress 

[PaulR]

Looking good, steady progress 

Cheers! Got the other end soldered up and all seems ok. Turns out my 'brass' towel rail is plated copper! No matter, it does the job.