Wobbler Engine Question

[Bernd]

I know how a wobble piston engine works and am in the process of building one out of Elmers book. It's called of all things "Wobbler".

Ok, now here's my question. I have noticed on all the wobbler engine plans there is a drilling template for drilling the holes in the proper position for the steam to enter and exit as the engine runs. How are these dimensions arrived at? ??? I've never found an explanation in any drawing as to the hows and whys of the numbers.

regards,
Bernd

 

[shred]

I ran across an article on it a while ago, but can't remember where. Anyway, it's basically determined by the distance from the pivot point and diameter of the crank. There's an article on working it out for a given engine on Dave Goodfellow's engine site: http://www.davegoodfellow.com/brassy-2.html

 

[Bernd]

Thanks Shred and thanks Dave. That clears up how the numbers are arrived at. I figured it had something to do with the throw.

Regards,
Bernd