20 cc Horizontal 2 Stroke Diesel

[Brendon M]

Hello Roger, you sure have been busy!

...All done with CNC (count number of cranks).

I am glad to discover that I have actually been doing CNC this entire time

[Roger B]

Thank you Brendon 

Next up was an oil tank. This was made from a length of 20mm dia 2mm wall brass tube (a 'trial' cylinder liner from my vertical engine). This is rather thick walled but allowed the connection union to be screwed in.
The base was a piece of 2mm thick brass strip silver soldered in place and then turned to match the tube. The bracket was from the same material this time soft soldered on. A hole for the union was tapped M5x0.5.
The cover was turned from a length of 20mm diameter aluminium. There is a 1.5mm breather hole and the O ring was one from the experiments with an O ring as a piston ring on my vertical engine.
The turning was done using the 4 jaw SC chuck as it is on the lathe for my injection/floating reamer holder experiments.

[90LX_Notch]

Roger-

Regarding Pic 470, did you plunge cut with an endmill in your drillpress?   My drillpress would self destruct if I did that.  Your's must be a very rigid machine.

-Bob

[Roger B]

Hi Bob,

I have a Chinese 16mm capacity bench drill with the normal amount of play in the quill system. I find that it is generally ok for spotfacing. As this time I had to deal with a step it was done in several stages.

Drill 4.2mm
Spotface with an M4 counterbore (~9mm diameter)
Finish with a 10mm endmill
Open out to 4.5mm
Tap M5x0.5

[90LX_Notch]

I see, most of the material was already removed.

-Bob

[freefuel]

Roger why did you go with spark ignition, when glow ignition seems closer to your eventual goal of a diesel engine?

[Roger B]

I chose spark ignition as I am familiar with it and have all the pieces. Glow ignition would add more uncertainties. I know that the ignition system and carburettors that I have work with petrol on my 25cc horizontal engine so I just have to sort out the two stoke induction/porting system on this engine. There is already a cam available for the fuel injection pump so I am using that for the contact breaker.

[Roger B]

A bit more done. I soldered the nipples on the oil pipes and then moved on to the piston rings. These were made as before, turn from a piece of CI bar, split, heat treat and then skim to size.

[Roger B]

With the rings complete I could start the final assembly. For the side plates, cylinder mounting and transfer cover I used Blue Hymolar as a sealant the rest used normal gaskets. Finally I turned it over with the battery screwdriver. There appears to be crankcase compression and normal compression 

<a href="https://www.youtube.com/watch?v=P7nhqI6YPTE" target="_blank">http://www.youtube.com/watch?v=P7nhqI6YPTE</a>

[fumopuc]

Hi Roger, I am still following along. This kind of piston ring making, I have to try it soon.

[Admiral_dk]

You can't be far from the first pop now 

[Roger B]

Thank you both  Achim, the piston ring making is shown better in my horizontal engine thread.

I connected the oil pipes and then primed the system. If I just fit the bottom bolt to the pump I can tilt it away from the worm and prime it with a 4mm socket in the cordless screwdriver. As this will reach 500 rpm it is the same as running the engine at 10 000rpm. I set the crankshaft to BDC so the main bearing ports aligned, blanked off one main bearing feed pipe and pumped oil through the crankshaft until it came out of the union.

As a two stoke novice I have read that the transfer ports should open with a pop or crack. I have tried to record what this one sounds like, is it reasonable?. The intake will suck on my finger and if I block it the pop goes away. Hopefully enough crankcase compression 

<a href="https://www.youtube.com/watch?v=HHDFFuaeVJs" target="_blank">http://www.youtube.com/watch?v=HHDFFuaeVJs</a>

I was not happy with the initial head gasket and as I suspect in diesel form I will be playing with compression ratios and bumping clearances I decided to make a proper punch system as I did for my vertical engine.

[yogi]

A very cool project Rodger! 
I'm still following along, getting exited for the first pop...

[Roger B]

Thank you Yogi 

I punched out a new head gasket, put the cylinder head on and then contemplated the size of the cooling hopper and length of the exhaust pipe. I am undecided as to going for the full height of the screw box or stopping at the bottom of the white table 

[Roger B]

A few more bits. I made a set of M3 brass nuts for the carb, exhaust pipe and cooling water tank studs from 5mm hex bar. The length for the exhaust pipe was guessed and silver soldered in place. I also started on the base plate in my usual way by gluing a thin metal plate onto piece of plywood. Next up is the cooling water tank. The base is made from 1mm thick brass with a 1mm reinforcing plate around the fixing/water passage area. The sides are folded from 0.8mm brass sheet. The seams on this part of the tank will be silver soldered so I can later soft solder a cover/splash protector on top if required.
Finally I made the M3 studs for the inlet, exhaust and water tank from free cutting SS.