Engines > From Plans
Roy Ozouf's Coventry
kvom:
I saw this engine running at NAMES, and was able to locate the source for plans. It's a booklet that's sold on EBay titled "Three Elegant Oscillators", published by Cammelback Press.
Here's a video of it running:
http://www.youtube.com/watch?v=zHMdw0xglFI
The name Coventry relates to an Englishman, Don Coventry, who found a similar engine in a surplus store and published a picture in Model Engineer. It's unusual for having the pivot at the bottom of the cylinder rather than at the center, as is the case with the McOnie.
Since NAMES, I received the booklet with the plans and have been modeling it in Solidworks for the past few weeks. The parts are all numbered neatly and total 66 unique ones. Obviously a few need multiples. I found only one minor issue with the drawings, which are all in imperial dimensions. The flywheel is 5.25" in diameter, to give an idea of its size. The following are renderings which show how the engine is built:
I ordered a flywheel casting from Martin's Models, and the rest will be built from bar stock once time allows.
sshire:
OK. You're definitely ahead of me. :ROFL:
I've been looking at the plans on and off and they are nicely done.
It will be next in line after the PMR ¼ horse vertical. I'm still kicking around the idea of modeling the frame, 3D printing it twice and having Cattail do a set of castings.
jeff l:
I think that this engine was featured in MODELTECH many years ago , Roy included his method on machining the frames from solid stock using a fixture plate on a rotary table .Jeff
tvoght:
I received the book yesterday. It appears the book is a reprint of the Modeltech article Jeff mentioned (and two others). It's a nice set of plans. The engine was high on my list, but while waiting for the book, a couple more engines have creeped onto the drawing board. Now the list is being reshuffled -again-. Sigh.
--Tim
kvom:
Since several have received the book, I'll mention the problem I found with the plans.
On the valve block, the exhaust channel passes too close to the bottom steam port. Easiest solution is to make that port less wide and the exhaust port wider.
Solidworks says frame volume is 78.17 cubic centimeters. STL loaded to Shapeways says 78.28.
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