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| Arnold building the "Little Blazer" |
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| sbwhart:
Looking good Arnold you make real quick progress :thumbup: :thumbup: Stew |
| madjackghengis:
Hi Arnold, It was good to see the crank being machined according to the instructions, and from the looks of the cam, it's right, and in keeping with my last post, I still think you will do just fine with the piston you have, and you definitely made a good choice in your deliberate decision. It looks like you're right close to being ready to start it up, just a few more pieces. Very nice work with the log as well, very easy to see your work. Now I'm really looking forward to that video :poke: The "Mad Jack" came out of the fact I used to run when I was a Marine, and did so both in the morning, with my Marines, and at noon, for my own pleasure, hence the "mad". Just a couple more pieces..... :) I really want to see how that cylinder works out for you :nrocks: mad jack |
| arnoldb:
Thank you very much Dean : ) I don't know about "just like a machinist" yet, but I must admit that I'm pleased with the progress I've made in learning to use my machines. I have a lot to learn still, but that's all part of the fun! I forgot completely about using an old ball bearing for whacking down the threads on the bottom of the T-nuts - must have been the heat-of-the-moment ::). The last couple of times I made T-nuts, I actually just didn't tap them all the way through with the last tap in the set. It might be better to tap them through though and then flatten the last thread; I think the bolts/rods screwed into them will stop more solidly and not try to seize up as much in the taper thread left by not tapping all the way through... Nick & Stew, thanks ! :lol: OK Mad Jack - you won me over with your explanation ;) and thanks! There's still quite a couple of small parts to make, and these take the most time ::) The cam fork (and I have been known to end up with a "forked" fork!), roller wheel, valve, valve plate, valve spring, M2 set screws, -bolts, and -nuts and of course the base, flywheel and burner. Winding the spring from an old guitar string will most likely require a jig as well and I have to make the slitting saw to slit the valve face (or cheat a bit!). So I'm only about half-way there! By the way, does anybody have a suggestion on "soldering" the valve plate to the valve ? Mr Duclos does not specify anything beyond "soldering" it - would ordinary electronics solder (the old 60/40 type with real lead and tin) do the job, or is it better to silver braze it. I don't know how hot the valve gets in operation; maybe the solder would melt? Kind regards, Arnold |
| madjackghengis:
Hi Arnold, I'm glad the name thing is cleared up, but I answer to almost anything, as far as soldering, I have taken a worn out valve and soldered a piece of fresh brass to its face, and it lasted a few minutes and the solder was melted. It was Sn63 Pb37, technical grade electronics solder. In making the valve, Mr. Duclos suggests making a one tooth slitting saw, and putting a slot a few thousandths wider than the thickness of the spring, and having a radius at the bottom of it, matching a radius put on the end of the spring which is bent to be at right angles to the cylinder. I used an actual slitting saw I had, fifteen thousandths thick, and it has worked well, however I have seen several other engines of this design where the builder simply bent the "spring", which in my case is a piece of brass shim stock, such that it was held flat against the valve face, with a very slight amount of spring pressure, as there is substantial surface area to be reckoned with, friction wise, and those engines seem to perform better. With your cast iron cylinder, I expect a bronze valve would work fine, but it is a bit of work to cut out the area around the raised section in the middle where the slitting should be, and then cut the plate its self off the bar it is made on the end of, and then face off the cut side afterwards. I've done it about three times and it's much easier the second time, but I wished I'd have made the valve just out of the flat of the spring, or, now with my experience with aluminum cylinders, made it using similar technique, but out of a motor brush of graphite, which would be both lighter and non-galling on the aluminum. To make the spring its self the valve, I'd go with a piece of brass shim stock about fifteen thousandths or so, cut to width a bit wider than the port, leaving extra length, clipping the corners on the other end and rounding it out, then bending it at just less than ninety, holding it against the valve face and finding where the valve rod will hit the bent up end, drilling it with the barest of preference to the outside, to allow for some spring force against the cylinder, then setting it up with two nuts centering it in the threaded area of the valve rod, and cutting off the excess about twenty thousandths past the outer edge of the port, then removing the shim stock and radiusing the corners by the port, and putting a radius on the end edge so the tip of the valve spring won't catch in the opening of the port, as it slams shut, as the cam is designed to do. From there, it is a matter of adjusting the nuts to ensure the valve completely seals the port, but has no excess travel which would reduce the open time of the port. To do the valve as Mr. Duclos specified would be to do essentially the same thing, except a couple of millimeters past the bend for the valve rod, you would have to bend it away from the valve face, with about a forty five degree angle, then bend it parallel to the port face for a short distance, and then bend it sharply in a right angle, to return back to the port face, and cut off the end, so it just about touches the face, and then put a radius in the end, to hold the bronze valve and keep it from sliding down under the influence of gravity, (it's the law) but having just enough spring to hold the valve plate in place while running, while not enough pressure to insert too much friction in the valve action. With such a valve, a piece of spring wire could be used with a loop for the double nuts for adjusting the valve opening, and with two ends bent at right angles, and cut off to insert in two shallow holes in the valve, not penetrating the valve its self. I will try to find a picture of an engine of this sort with the flat valve made straight out of the shim stock or spring steel if I can. :jaw: mad jack |
| Gerhard Olivier:
Nice job on the engine Arnold And congrats on the Engine of the month!!!! :thumbup: Gerhard |
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