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Hugh Wilkinson, Christchurch, Dorset, England, email@example.com 8/16/2010
Horizontal Hit and Miss #1
Let me first say thank you for giving me the opportunity to build this little hit and miss engine to your design by making the drawings available on line. Over the years I have built many steam, petrol, hot air, vacuum and stationary engines, but never a hit and miss engine, in fact I did`nt even know how the govenor system worked, so have really enjoyed making this engine.
I am now well into retirement but spent most of my working life as a mechanical draughtsman, so am unlikely to build something exactly to someone else`s drawings, but in this case have worked as closely as possible,
changing things only to suit materials I had to hand and to suit my particular ways of working.
Unlike you I did`nt make my own gears this time, but in the past have spent a couple of weeks making cutters, to make gear cutters, only to spend about an hour cutting the actual gears. Off the shelf gear cutters I find expensive as a pair are needed, and unless you have gears to cut with the same DP and similar numbers of teeth these may only be used once. Also in the past I have made piston rings to a similar process as you describe, but as you say the temperature does not exceed 120F I decided in this instant to use a nitrile O ring which will handle 100c continuously and 150c for short periods. This gives me a gas tight seal with minimum friction.
I intended to use buzz coil ignition like was used an the model T Ford cars and although it started more or less first time, the speed was not much more than the hit and miss speed, so I changed this for an electronic system which I had and this ran much faster, but is still very gas critical. I also tried it with conventional points,coil and condenser and this also ran OK. As you can see from the photo I have mounted the engine on a little trolley which is a little over big for the engine, but the intention was to use a fairly large 6v motorcycle coil which I had to hide but which I do`nt use now.
Up the front end is mounted a little butane/propane gas tank which I made, and at the flywheel end is mounted a little box to hold the electronic circuit board and a small battery pack.
So thanks again for providing me with these drawings and I hope you like my interpretation of your design.
I have included a few more pictures showing some detail, one shows the relatively small coil fitted on the underside and one shows the small 6v battery pack and electronic circuit board.
You ask whether I built in inch or metric, well inches are my preferred way of working especially for model engineering, as most of the models I build were of bygone days and therefore scale down much easier.
During my drawing office days we had to chop and change between inch and metric as our customers wished and one was just as easy as the other, but in the workshop its a different matter as your machines unless equipped with digital readouts, are ether one or the other. I do use metric drills as these are more readily available, but never use ISO metric threads, much preferring the BA (British association) system which I think is an altogether better system. Actually I do not understand why in this country we have been so keen to jump into metric, is this because it makes us more European?. We should not forget that it was the inch system that drove the industrial revolution.
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