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| bogstandard:
Nick, Don't worry about covering up the blunder, the wick will take care of that, besides, after a few runs the area will be filthy black anyway. The only thing to really worry about is if going slightly deeper has changed any of the running or starting characteristics. They are a pig to start at the best of times, until you find the sweet spot for the flame. I couldn't get mine to run at all with Jan's angled wick design, and came up with my own fixed position vertical one, which gives much better running and starting. In fact when I told and showed Jan about it, he incorporated it into his latest twin cylinder design, which runs very well. The most critical part on this engine is what you should be coming to soon. Make sure you have the barrel bore and piston perfectly smooth, parallel and lapped together. The piston shouldn't drop down the cylinder, but gently slide it's way down under it's own weight. There will be no lubrication used in the bore at all, the two parts are designed to be self lubricating, by using the carbon content in the cast iron of each one. Oil will stop it dead, and it won't restart until you have cleaned every trace out with spirits. John |
| NickG:
John, Good point, probably won't be able to see the blunder. Thanks for the advice on the piston / valve. I think this could be the bit I struggle on. I noticed that Jan changed his design after yours and did a bit of a study to show the best place for the wick. He seems to think it is vertical and right behind the port, seems strange but am sure I will have to try many positions. Might tackle the piston tonight, I still need to make the small bushes for the cylinder too. Nick |
| bogstandard:
Actually Nick, it was myself that gave Jan the original settings for the wick, but mine were based on 1/4" (6.4mm) not the 8mm he has ended up with. I found that the 1/4" gave the best all round performance, and I experimented with both larger and smaller. Without the vertical wick, as soon as you try to move the engine, it will stop dead. With the vertical wick, I can actually carry the engine around and even run it outside, a thing that Jan marvelled over, as before that, it was almost impossible. That has to do with the position of cold air pockets around the inlet hole. Getting too technical now, so I will leave you to it. I am sure that you will get it sorted. A little bit of advice you won't find on Jan's plans, wash out the ballraces with spirits to get rid of the grease and put only a tiny amount of thin oil in them. The friction reduces dramatically and will really help when you come to get it running. John |
| NickG:
Darren, good point there about climb milling. I’ve managed it in the past but maybe it was the softer materials that allowed me to do that. I am going to avoid it like the plague in future now! Good tip there John, thanks. I received my ball races from Arc Euro yesteday and although I obviously haven't tried them properly, there did seem to be a bit more drag than the ones I used on my hot air engine, but they felt smoother at the same time. Right, will post last night’s progress. This was basically finishing off the cylinder, that is, milling the two flats + drilling and tapping for the pillars and drilling the long hole for the valve rod. Setting up perpendicular to the port face to mill flats: Flats milled – nearly took 2mm off but thought it look enough when I got to just under 1, so checked the drawing again and it was infact a 1! Holes centre drilled: Opening up to tapping size – changed this to 2BA which was nearest I had to 4mm: Tapping – was thinking of doing this under power but leaving it not too tight in the collet so it would slip. Chickened out though and turned the spindle by hand! I was always taught to go 1 turn forward ½ turn back anyway. Set up to centre drill and drill the long hole. I used the square just as a check that it was clamped correctly. It worked really well with the 4mm drill, didn’t seem to wonder off at all, it’s come out spot on. The only thing was, there was something funny happening with my milling machine when drilling that long hole. It felt like something was binding, either the spindle or gears the further down I went on the travel. Will have to look into that, I know the guy that bought the same one at our club has had trouble with his so will have to investigate. Right off to attempt the piston / valve now I think! Thanks to all for your interest, support and advice. :bow: Nick |
| Gerhard Olivier:
Good work on the cyl Nick Watching with interest Gerhard |
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