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My fault I'm afraid. I linked a model engine related picture from my Flickr account which also contains picture of industrial particle accelerators and it sort of grew from there.

The electrons cause X Rays to be emitted when they are stopped, Bremsstrahlung. Higher atomic number materials give off more X rays. Our 3 MeV systems are installed in concrete bunkers with 2m thick walls. At full power you would receive a lethal dose of X Rays in seconds if you were not already...

This was probably chemically cross linked using the Sioplas process. Pirelli in Southampton was working on the process when I started there in 1977. BICC further developed this to the one step Monosil process. Pirelli and BICC didn’t install electron beam facilities until the early 80s.

A 3 MeV electron will penetrate around 10mm of polyethylene, less in higher density materials. The electron source is a spiral of tungsten wire about 1 cm in diameter, there is a picture of one in the white paper. As the beam is 10s of kilowatts we don’t want it too tightly focused. If it goes...

Thank you 👍 There are two sets of none engine photos. One is a visit to the Diamond light source: https://www.diamond.ac.uk/Home/About/How-Diamond-Works.html The other is various industrial electron accelerators used for crosslinking polymers, which is my day job. I am responsible for...

I was not sure which he meant but as he quoted a section refering to the piston and combustion chamber I took it to mean that. For the injection pump and plunger I like to think I have a clearance of a few microns however once again I have no means of measuring this.

The Acrolap is a split brass lap with a tapered expander which is designed to reduce the chance of bell mouthing the bore. I have used them successfully on a number of engines. I use the smaller needle laps for my fuel injection components. At the end of the day getting sensible measurements in...

I don't actually know, I don't have sufficiently accurate measuring equipment. I turn a plug gauge to the planned diameter and use this to check the bore whilst lapping. The bore is lapped using an Acrolap, https://acrolaps.com/index.htm , and 40 micron diamond paste. The piston is then turned...

I am a little confused by the brass fitting on top. I guessed cooling water as the injector should spray into the hot bulb.

I think that the block on the back of the crankcase is the inlet valve (closed by a spring) and the transfer passage is on top of the cylinder block. The exhaust port is under the block.

Does it have a connecting rod and piston? Can you remove the cylinder head so we can see the combustion chamber? The main part that is missing is the fuel injection system, but as it is a hot bulb engine this should not be too difficult.

Helix controlled injection pump: My first injection pump was used for manifold injection on a petrol engine so a variable stroke controlled by a wedge was adequate. For the diesel trials a more defined start of injection was required so I decided to go for a helix controlled jerk pump. I had...

Ruben sent me a message asking for details of my latest needle style injector and an early design of helix pump. I will post them directly in this thread in case anyone else is interested. First the new needle injector: This was designed to overcome some of the manufacturing problems with the...

The ~1.5mm is the maximum mechanical stroke. The cam lift is 3mm. The inlet port is 1mm diameter and I set the pump up so that the inlet port is completely open. This means that the start of injection is after at least 1mm of stroke, depending on how sharp the inlet bore and plunger are, leaving...

It looks and sounds great to me for a first start. Don't forget that in an opposed piston engine the other piston supplies most of the balance.

This may be a more explanatory picture from the Holzapfel catalogue.

Have you looked at the Maudsley steam engine valve gear? It used a parallelogram of gears to adjust the phasing of the crankshaft and eccentric shaft to adjust cutoff and change direction.

This discussion isn’t really relevant to Ray’s engine as it is a four stroke but is interesting never the less. The conventional port controlled two stroke is a very simple concept but the inlet (transfer) port and the exhaust port have to be adjacent and open at the same time. It also tended to...

The Junkers Jumo 204/205aircraft diesel engines were a twin crankshaft design and had the two crankshafts offset by, if I remember correctly, 9°.

The devil is very much in the details. The main reciprocating forces are fairly well balanced, the pull rods can be quite thin section as they are loaded in tension and don't have significant buckling forces. The Junkers engine I am building has a shorter stroke for the upper (induction) piston...