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| madjackghengis:
Hi All, well Bernd, this is North Carolina, we don't keep snow more than a few days, as we prefer rain, thank you :lol: even the dogs prefer rain, although they do get very excited when they encounter knee deep snow which they haven't seen since they were pups. Just a week ago, they were all, including the one not in the picture, dancing with glee, with plenty of "air time", and eating the white stuff. But, back to the engine, I don't much like stainless, it has a few places it belongs, and is almost irreplaceable, but otherwise, it should hide and be hard to see, in my never very humble opinion. Fortunately, I found a cam from a lawn mower engine, tested the shaft with a hacksaw, cut off the gear with meat for a hub, and started turning. A couple pics are already posted, here's the facing, having put the stainless flywheel on a shaft, and found it inherently unbalanced, something to do with the nature of stainless, and the different metals migrating to their own part of their world, and not liking to be spread throughout the piece of metal. So, on with an iron flywheel, as engines are supposed to have. facing off the flywheel for final finish, after the teeth are gone. with an extra long center drill, then the tap drill held in the very end of the chuck jaws, barely reaching through the hub, and the tap with just enough square showing to get it started straight, tapping the hub for a set screw in #4-40 tapping finished with an adjustable wrench, nice cast iron, smooth and consistent, easy to work. the engine apart so a hole can be tapped for a pivot post for the valve actuating arm, the pivot is at the base of the crank structure. another shot of the disassembled engine and some spare parts for the valve set up. The flywheel should get some weight reducing holes today, along with the final determination of what kind of valve will be used, I'm kind of caught between a swinging valve plate, and the sort used in The Poppin', coming up from underneath. I'm sort of waiting for the lightbulb to light up. Some stainless sheet from a computer printer is waiting to be cut into proper shape, depending on which direction I go in. more to come on this. mad jack |
| NickG:
Nice stuff Jack, I've seen both types of valve working well. Will the poppin type be easier to establish and maintain the seal because of the angle it moves up at? It moves up and down in an arc so as it's closing it's pushing nearer to the cylinder against the springiness of the valve material. This may be easier to set up initially than a swinging one, just a thought. Then again, do these just rely on the fact that the valve is really thin and the suction keeps it against its face? Nick |
| madjackghengis:
Hi all, getting further along, I don't know why things work out the way they do, Nick, I think the "poppin" works freely because there is almost no friction with regard to the valve, as only the swivelling of the shaft in its bearings, and the slight pressure at the closing of the valve have any real "bearing" on the friction issue. I know that valve friction is important in the Duclos flame sucker, because I've tried several different valve types and have reverted to the spring pressure bronze plate with the tiny slot as the freeist moving. On this engine, I was struck by the nature of some of my scrap, I knew I had a piece of metric ground shafting, small, and with two sintered bronze bushes which came out of a CD player, and I found the box with the scrap from that old player, and the light lit up. First, I had to get rid of the stainless flywheel, so I got to work on the cast iron one center drilling the iron flywheel for nine holes step drilling my way up to size a half inch set of holes is all that would fit where I put them, but it seems like a good flywheel, on just a straight shaft in the main bearings, the flywheel stops at random, so it's pretty well balanced as is the flywheel in place a frontal view of the flywheel on the engine, note the second "extra" hole, put in to balance the hole that was already in the gear. that 7.62 by 54r casing isn't just there for looks, it is what I used to press the bearings onto the mainshafts, with the pressure entirely on the inner race to keep from damaging the ball bearings drilling the cross hole in the valve shaft stanchion for the 2.5mm valve shaft, the other cross hole is to the left, in the shaft in the vise jaws facing off one stanchion to length, measuring from the "bottom" of the shaft hole to the base of the stanchions facing off the other to match, both have been drilled and tapped #4-40 stanchion with valve shaft pressed in place, sintered bushings along side stanchion and shaft with allen screw in the base of the stanchion making the valve carrier, narrowing it for clearance more milling, started with quarter by one inch 6061-T-6 bar, reducing end to 3/4 inch final cut to size, time for drilling for the valve shaft after center drilling, drilling through with an undersized hole no reamer that size, finishing with a sharp drill on size the valve shaft hole with bushings pushed in place with loctite another view of the valve shaft bushings machining clearance in the top of the valve carrier machining down the carrier, making room for a valve between it and the head more trimming, with a flycutter, holding the carrier by less than an 1/8th inch in the vise taking finishing cuts, checking for clearance against the stanchions and head surface for reference finishing the other side beyond the bushings final cuts over the bushings, to ensure they clear the head in action as well the valve carrier blank finding a piece of bronze .875 in diameter with a spigot on it, I turned down the spigot to a quarter inch, and chucked on that spigot to face off two thirds of the thickness of the valve more facing, final thickness will be .090 inches with the valve to size, taking a cut to "hollow" the center to reduce the area of contact leaving a good .200 rim laying flat on the head surface for sealing. the hollow is about fifteen thousandths deep, just enough to relieve it. after center drilling on the marked spot, drilling through the valve carrier with the spigot on the valve turned to .248, reaming the carrier hole at .250 some bandsaw profiling, and filing to a fine finish, the carrier end finished the valve sitting in the carrier the carrier with the valve, mocked up on the head with both stanchions pressed on the valve shaft, with the valve carrier cut to fit, the valve gear fit to the bracket and the valve in place against the head, fitting nicely, freely moving, with a good vacuum seal being the final test. This wasn't exactly what I thought I was going to do for a valve, but it turned out nicely, and fits well, funny how those lightbulbs sometimes don't exactly end up making parts you thought would be there. This valve is inspired by Herr Bettinger and his #2 Flammenfresser, which runs too well not to copy from. Next, I will have to make the operating lever and cam to move the valve in time and space, and maybe look at some sort of frame or something. Thanks for watching and all the comments, I'm having more fun than a human bean is supposed to :poke: mad jack :lol: |
| NickG:
Great work as always Madjack, I've never seen a valve like that before but looks a good idea. What keeps the valve against the port face though? Is it designed to blow off the face as the piston nears TDC and the pressure increases? and what will keep the carrier from pivoting on its shaft, or is it supposed to? Very intriguing build this. :bow: NIck |
| sbwhart:
Very interesting stuff their Jack is this your own design ?, some great work. I hope that pineapple isn't live :D Can't wait to see it running Stew |
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