I called this topic 'junk box engine', not because I found it in a junk box but because I built it from stuff found in my junk box. This is something I truly get a lot of satisfaction from doing because you end up creating something from nothing. You know what its like.. you go routing through your junk looking for something and come across one or two useful looking bits of material, the brain wanders off the current job in hand :Das a cunning plan begins to form and then you're completely sidetracked into another project! Story of my life that is!
In the case of this engine, I found a couple of plates of duralumin and a length of half inch dia brass tube and as I always wanted to make a V twin engine, I figured these would form the basis.
I get the biggest kick out of dreaming it up and building 'on the hoof' as it were....no plans or drawings.. all in the head and machining and assembling as I go. This engine was made entirely of materials from my scrapbin and took a weekend to build.
The engine is a 60deg double acting oscillating type with 12.5mm pistons grooved to take silicone O rings and a crank giving a 20mm stroke. The adjustable glands in the cylinder end caps contain O rings to seal the connecting rods which are plain ended running on a 4mm stainless crankpin. The crankshaft runs in ballraces and is virtually frictionless when spun over without the connecting rods hooked up. It also has a displacement lubricator set in the middle feeding both cylinders . The steam control valve came from an old dismantled Wilesco stationary engine.
In the absence of springs with which to tension the cylinders against the valve faces, I machined up some brass cups which retain silicone O rings, the whole being pre-tesioned with locknuts and set for good sealing of the valve faces at pressure with the minimum frictional loss. There is no reversing valve as time did not permit the construction of one but if I build a MK2 version, I will change a few things as well as designing a valve.
The machine runs exceedingly well and is silent and leak free. Being an oscillating engine, it is naturally very wasteful with its steam as there is no variable cut off but it runs at anything from one and a half psi upwards and at 15psi off load, I clocked it at 2000 rpm. Using a Buhler multipole motor as a generator and applying a variable load, I managed 9volts at 0.5 Amps... 4.5Watts!!, but unfortunately can't remember the RPM figure.
The engine has been run for hours and at one time, I had it hooked up to transistor radio in the workshop and spent a couple of days running it and listening to the radio but the steam made the workshop environment a bit too humid and the oil went everywhere as I would periodically fire a squirt of oil at the bearings to keep them happy. The whole thing was such a distraction I couldn't concentrate on my work and had to shut it down and put it a way. I guess will never grow up and become sensible... God help me if |I ever do... that will be the end of me!
One day... it's always one day isn't it, I with build an old steam driven tug model to fit this engine into as it's got loads of torque and should turn a fairly large prop... perhaps when I get those 50 other jobs and projects done! ::)
