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| NickG:
Yep, I'll be watching too Jack nice work. ... I still have a few parts to finish my 2nd poppin, just can't get any time to do it :doh: |
| madjackghengis:
Thanks for all the kind comments, I will try to make this as interesting as possible as I move forward. Having turned, cut off and reamed the flywheels, I discovered my reamer was cutting a bit over sized so I tried to use locktite to take up the mainshaft space and ended up with the wheels out of whack, and had to turn down two shafts oversized by three thousandths for a locktite press fit, while turning the shafts themselves half a thou under for the ball bearings to slide on, but it worked out well, with the crank pin hole reamed with a different reamer, on size Now, measuring between the wheels, I've got about an extra six thousandths, so I'm making the two piece rod end out of quarter inch brass. It is made with a tongue and groove, tightly fit, and soldered together for machining the crankpin hole, the rod end threading, and the bolt which will hold it together when complete the first piece is milled with a slot with a 1/4 end mill, and then a couple thousandths taken from each side for clean up and smooth surfaces. The second piece is the "tongue, which is machined to a snug fit in the slot, and the two pieces cleaned up with a file so there is no visible light to be seen between them. Ensuring no excess end room is essential to proper bearing clearance lasting for any length of time so a fine file and care is the key here. I've laid the two pieces on a piece of graphite square which came from a water pump, and makes a good soldering heat pad which doesn't get damaged, and cleans off nicely. The two pieces are wiped all over with zinc chloride, particularly between faces as a good general flux. I use SN63/Pb37, high end electronic solder as it flows the best and wicks into the smallest spaces. It's not good for structural strength, however its wicking ability and low temperature often make is useful even in such situations, although this one is just a matter of ease. Soldered together, I use a six inch file to remove the excess solder and to get the faces flat and parallel. With Optivisors and a scribe, I mark the location of the crank pin hole on the solder line at the end of the tongue measured right in the middle. This will be step drilled and reamed for the quarter inch crankpin. The block is clamped in the mill vise, drilled, stepped up and then reamed, with a nice tight bearing as the outcome. After that, the block is turned on its side for the clamping bolt. This hole is tap drilled through, clearance drilled about half way through the tongue, so the threads are partially in the tongue, to secure it in place, yet allowing the "strap" which one ends up with, able to pull up tight with the cross bolt, in this case #4-40 I centered the rod end in my four jaw to drill and tap it for the rod, and to turn a taper on the blunt end of it, making it prettier since we all like pretty, right? Cutting the taper is mainly an exercize of not cutting the jaws and stopping when it looks "pretty" Taper turned, drilled and tapped, now time to round off the 45s on the other end. Starting on one side, then to the other. once both are closing in on a radius switching back and forth makes for a good looking and equal radius. A clean up of all edges and it's ready to take back apart and see how it fits. That about finishes it up for today, got to go start getting ready to pull out the dozen trees I lost in the hurricane, as the water drops, and I'm about to be able to get my tractor across the bridge to where the trees came down. I expect I won't have to worry about wood for the next five or six years, heating the shop. I lost half a dozen oaks more than seventy feet tall, half a dozen maples and a few big sycamores, and a huge Chinese elm, over a hundred feet tall and perhaps four feet in diameter. I hate losing trees, especially big ones. Cherrio, and thanks for watching, mad jack |
| NickG:
It really is a good method of making the big end that. I didn't bother with the soldering on my two but the outcome is better with soldering - a lot less room for error when drilling for bearing and pinch bolt. :thumbup: |
| cfellows:
Nice work! What size are the crank disks? Chuck |
| madjackghengis:
Well then, let's get on with another episode of the project, thanks for your input Nick, I took that design from your build log, seeing it as a good, solid and rather easy way to build a good solid big end bearing. I would also say, if it wears loose, as they tend to in steam engines, they can be disassembled and tinned, just in the bearing area, and then scrape fitted and you have essentially a babbit bearing surface, and a few thousandths can be taken up that way. I like their simplicity to make, and the ease which they dissassemble. finding the end of the cylinder to determine where the main bearings should go, using a wiggler on the back side of the head. I use stainless for the heads of these because it does a very bad job conducting heat, and since the flame hits the head first it is good for it to wait until it's in the cylinder before it cools. Someone, I believe maybe Nick, said turning a taper in the port leaving almost a knife edge for a lip is recomended in the "Poppin" plans, for the same reason. It is rational and logical, and the smaller the engine, the more important the losses are so every little bit helps. I have also turned the heads a bit larger in diameter than the cylinders so they reflect the flame away from the cylinder, and polish their face well on some paper, working up to 600 lapping it on a surface plate. It makes a good seal, and I suspect reduces the temp a bit, but no way of easily measuring without a lab. With the con rod made out of 3/16ths key stock I'm using a four jaw to turn it down for a #8-32 thread to fit into the brass "big end" previously just tapped. I had to turn a taper in the rear of the cylinder liner to clear the rod as it was touching as the wheels rotated. Another shot of my die setup, a piece of hex cold rolled, with five eighths bored one end, three quarter the other, and reamed through with half an inch. Four set screws to hold each die in place and a fuel pump rod from a chevy, which is tool steel, hardened and dead on .500, to clamp in the tailstock chuck. The dies sit flush and square with the bore, the four screws allow good adjustment, and I get good straight threads usually, wish I could say I made it, but it came from the kit of a man long gone and his son with white hair before I got to buy it from him. with all the other parts where they were, it was time to find the main bearing position, you can either use math or judgment, but the rod has to clear the bottom end of the cylinder as the crank turns. Having drilled quarter inch holes where the mains should go, I put it on the bench to consider how to set up the valve arrangement. After several hours of un-productive consideration, and running into some interferance between bolts, I decided I didn't like how it looked, or even how it could look, and started looking around the shop for inspiration. I noticed a couple of forgings from a lawn mower engine, rods which move the counter-weight reducing engine vibration. After wiping them off with a rag, the engine having tossed its rod out, I decided they had to be the frame as they looked right, unlike what I'd already made. They are matched forgings of aluminum, the large circle is about 2.200 and the small hole is .480 they need a home, as their last one broke open, and they look like engine parts, what more could a fellow ask for? I took a scrap piece of 2.5 steel bar, turned a shoulder to take the big holes, found a bit of distributer shaft which was a push fit in the little end, then clamped the pair on the jig on my mill table, and using the wiggler, lined the centers of the two holes up so I could get the cylinder base mount holes in perfect alignment. with this, now I have to make the new cylinder base, setting it up for the four cylinder holes and the four frame bolt holes in the edges. The plate will also be scalloped on the sides for bling purposes. with this done, the next step is to bore the small holes to hold the main bearings. The forgings are almost half an in thick, so I'm boring only .190 deep, the thickness of the shielded bearings. centering the hole for boring boring the hole boring the second side finishing to size, frames ready for the next step with the bearings fit on shafts an extra cam from my last engine, testing the fit of the frame and setting up end play for the mains Another shot of the partial engine, ready for valve train work in this position I see a way to run the valve, I just need to mill that fancy curve so the inside ends of the frame mounting holes are exposed, and a shaft matching the i.d. of the tap drill will pivot between the two mount bolts, which can establish fixed end play. a series of shots of the big end of the rod completed and fit to the crank pin the rough assembly with the cylinder plate milled for the valve shaft, almost just like in the "Poppin", just slightly different. I measured the distance between the mount bolt ends, turned a shaft to match the tap drilled holes, and with the intent of having both ends of the valve gear 180 apart, I clamped the shaft in the vise, centered over it, and drilled and tapped two holes for the two levers at #0-80. Since I changed my frame idea, I had to make a new con rod, to match new dimensions. With the valve shaft in place, it is easy to take some 1/16th drill rod, thread both ends for a valve rod, to carry a .006 in piece of feeler gauge, and thread one end of the leftover drill rod, and watch the valve movement with the cam pushing merely against the drill rod, bent to bear on the aluminum bronze cam. It worked so well I decided to make a judicious cut, then carefully bend the end of the rod around a piece of shaft, and have a round end of rod bearing directly on the cam, and in setting the timing, found the cam fits well with this arrangement, and is a very light and easily moved valve set up. I kind of sort of want to put this engine in some sort of vehicle maybe, so while it is complete except for mounts, I found some scrap pieces of stainless with a bend, and cut mounts out of it, for it to stand on for now. Feet straight up, resting lying on its back, you can see the loop which is the cam follower on it's side, showing all. Well, got to get to work, somehow I didn't get a shot of it on its feet, but I'll be posting a video tonight if I get the chance. Thanks for looking, hope you enjoy it as much as I do. cheers, :beer: mad jack |
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