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| kvom:
Points well taken John. My intention with the crankcase is to remount it in the lathe and use scotchbrite to debur around the edges. I don't have a deburring blade small enough to enter the mounting holes on the cam housing, and I was thinking I will just counterbore them. Sitting here typing though, I think that my little countersink bit might be a good tool to debur them. Since I don't have any brass the correct size for the heads, I'm planning to make the heads from aluminum and the valve cover from brass, just reversing the materials in the plans. Today I started on one of the heads. There is a lot of milling and drilling to do on a fairly small block of metal, but after a lot of studying the 3 separate drawings of the head I think I have it figured out. I did everything but drill and ream the holes for the pushrods, plus I need to acquire a 1/16" endmill to make the slot for the inlet. Pictures to come later. I spent about 5 hours getting to this point; for the remainder, using a vise stop to perform the same ops on all will save a lot of time. I still think it will take ~2 hours each. |
| bogstandard:
Kirk, I have already built a head inside my own, and really it is just a matter of backstop work and hole drilling in the right place, plus a little milling work, again using the backstop. It looks to be a difficult part to make, but isn't really. I usually scrape the burrs off, using an Olfa Laminate cutter. The blades are carbide, and if you are not silly and don't put too much pressure on, the blades will last for years. http://www.olfatools.eu/product.php?id_product=84 or this http://www.olfatools.eu/product.php?id_product=85 The cheaper one is definitely the best. Got to get me a couple more for stock. John |
| NickG:
John, I am now looking at the 1/16" deep divet (more like 1/32" now it's healed) that came out of my finger when I cut it on the burr on the flywheel of my rocking engine. It's a permanent scar for sure and it'll serve as a good reminder to me never to do that again, but we don't want any more reminders. I usually just deburr holes with a bigger drill or a csk and twisting it by hand and straight edges with a needle file. Guess I should probably get a proper tool. Nick |
| kvom:
Last night and today I made the first head. I still need a 1/16" endmill to finish a couple of minor operations, plus a 1/8" reamer, but this is it in essence: As can be seen, lots of holes to drill in 4 of six sides. On the top are 7 holes: 4 through hols for mounting to the cylinder, one tapped hole in the center for attaching the rocker bracket, and the two holes on the little "plastforms" for the pushrods. On "front" you can see 9 holes: 6 for attaching the valve cover, two holes for the valves, and one hole giving access to the cylinder. I still need to connect this hole to the right valve hole with an air passage, hence the need for the small endmill. The bottom side has two holes that open to the cylinder. On the left it opens very slightly to the rear of the left (input) valve hole. On the right it joins with the small hole in the front. The right side, a small exhaust hole joints to the right valve hole. I didn't understand how the valves worked until I had made the head and understood the interconnections of the air passages. While the plans seem accurate, there is very little in the way of explanations or assembly instructions. The valving works as follows: 1) The two valve holes are counter bored and will contain a ball bearing that is larger than the inner part of the bore. When the pushrod for a hole is raised, the ball seals that hole, blocking any air passage. The left hole is the input side. The air inlet in the valve cover opens to this hole. When the pushrod descends (pushed by the rocker arm), it pushes the ball outward permitting air to enter the cylinder bore. 2) Conversely, the right ball valve prevents are from leaving the cylinder until its pushrod descends. Then the piston's upward motion pushed air through the right bottom hole, into the lateral hole, through the small air passage, into the right valve hole, past the valve ball, and out the exhaust hole. Obviously the rocker arms must be out of phase by 180 degrees so that one valve is shut while the other is open. The valve cover was made next. I started with a 1/4" piece of brass plate, but mistakenly milled it to 1/8" thickness before milling the countersinks for the mounting screws. I don't have a set of parallels that will allow me to hold it securely to mill these now, so I will likely throw this one out and make 5 more. The inlet hole should be a bit further to the right as well. In any case, here's how the head looks with the cover attached: The hole in the left center is the inlet. I then made a rocker arm bracket, but I'm not very happy with it either. The top can be optionally rounded over with a file or corner rounding bit, but I made it slightly too thin so that the cross hole is not centered. Once again I think it's a throwaway. In any case, this shows how it mounts to the head: |
| chuck foster:
i have a question about this engine. liney offers this engine as just plans ($29.00) or you can buy a machinists kit ($98.00) that has all the fasteners,bearings and metal. now my question is, is the machinists kit worth the extra bucks?? i want to build this engine but i won't be able to start building till after the new year. chuck :wave: |
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