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| bogstandard:
Nick, I think we discussed this the other day, buying specialist bits in to make something when almost anything will do. This engine produces fly power, so if you could stop a sheet of paper from bending, that would do for the conrod, I just used what I had knocking about, as long as you can get the bearing to fit almost anything will do. With reference to balancing, this engine is a very slow runner, I just made a basic shaped crankweb and I had no balancing problems. --- Quote ---Not sure how it'll machine though --- End quote --- This is where a file and handpower springs to mind. As long as the holes are the correct distance apart, it could be made to any shape. Two washers with a bit of rod soldered between would even do it. LET GO OF THE PLANS SPECIFICATIONS AND USE WHAT YOU HAVE ALREADY GOT. I will see if I can get some piccies taken this evening. John |
| bogstandard:
Nick, I have got you some pics, I hope these will explain things a little better. As said before, please excuse the state of the engine. I will just explain a little about the big end area. It really needs to have a rigid fixing of some sort as if it is floating, it is liable to cause friction by being out of line at times. Even a tiny amount of the wrong type of friction will stop the engine running. These six shots show it from all angles, but you could use the same sort of setup, just with one crank. You do need to be able to disassemble fairly often, as muck will again cause too much drag and prevent running. So I just used a little finger screw to get things apart quickly. The crank web was just a minor attempt to balance out the weight of the finger screw. These last two shots show the position of the wick. It is exactly the same on the other cylinder. I use fibre glass strand wick which doesn't burn away like normal cotton stuff. I adjust for best running by pushing the bit of wick sticking out slightly one way or the other. This position gets me started after a warm up of the cylinders, then I tweak the wicks once it has a minute or two to warm itself up. You will also notice how much muck the burning meths produces, imagine that inside the cylinders. That is why I strip down and clean out with meths every couple of hours running. I hope this helps. John |
| NickG:
John, Thanks very much for your time and effort taking the photos, they are very helpful. I might have a think about the valve rod too, I am worried bending it I may bend the straight bit, yours looks silver soldered, not confident I'd get it perpendicular by that method though. Tonight I made the effort to get a little bit done. I am travelling down to south wales tomorrow, it's going to be a long day, up at 4:30am to get an early flight, I'll be back about 9pm and don't think I'll be up for the workshop - besides, it would actually be dangerous. As discussed with Bogs, I had pretty much the same idea as him although I've followed his as it was even easier to make from hex bar. No machining to show as it was very straightforward. I took a bit of hex bar, faced down to length in the lathe. Drilled and tapped a 6ba thread in one end about 5mm deep, enough to break into the cross hole for the rod. Then into the milling machine to cross drill the rod hole and drill and tap the striker hole 6ba. Here are the parts including a long 6ba bolt (striker), lock nut and a short 6ba bolt to clamp it onto the rod: Here it is assembled, need to make the rod next! I am still crap at taking photos, these were inside, it just wouldn't work with the flash, tried on a couple of surfaces. Am guessing the blue bedsheets were too dark and the white paper too bright :lol: Am getting there, if a little slowly! Nick |
| NickG:
Well, a tiny bit more done on this. I decided to bend the valve rod into that daft shape. I can see why it was done like that, I just don't like bending things though! Anyway, I fannied on for about an hour or so with this but it produced a decent result: I drilled the cross hole in the piston about 0.2mm oversize and the rod length was a few mm longer I think because of the hex striker block. Anyway, it's not critical, I know it's ok at the 2 extremes, the adjustment can be done with the bolt and the pinch bolt. It's a nice smooth sliding fit, hardly any friction there so looking good at the mo. I also got the bearings hacksawed out and marked so starting on those tomorrow night. Nick |
| bogstandard:
Nick, As you know, mine was made to the old drawings, which showed a silver soldered right angle. I just held the two parts in the correct position with a couple of small magnets about 1/2" from the joint and soldered it up. Yours looks just fine. Once I had the engine up and running, I filed off the rod very close to the adjuster, so it is dead easy to set up in the same position after stripdown. John |
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