How many of these valves do you need? It's looking good but sounds almost like a nitemare to do. Have you checkt your tailstock offset? I had a problem where I had to shim the tailstock up a thou or two once.Thanks everybody. It took me four tries before I had an acceptable valve, but then I made one this morning and it turned out better than the first. Using the advice given here I did several things different. First, I turned it with the top of the valve toward the headstock in the lathe. I center drilled the end and used a live center to steady the work.
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I turned the section of the valve head, .375” in my case, to size, then began turning the stem down toward .125”. I started with larger cuts, .015” off at a time and as I got smaller, I move to .010” cuts, then down to .005”. I used a live center on the stem end of the valve and noticed that the OD near the headstock was smaller than toward the live center. I assume this is due to some side play in the live center. So, as I got close to final dimension, about .030” away, I switched to a dead center and this helped a little but did not totally eliminate the OD difference between the two ends of the stem. I also used a carbide cutter for the majority of the material removal, but then switched to a rounded HSS cutter as I got close to final dimension. This gave me a much nicer finish. I turned down to about .006” over and switched to emery cloth – 320 grit to start with. This removed material and gave a nice finish, but was taking too long. So, I went back to the round nose HSS cutter and took the stem down to .003” over. I also worked from the tail stock toward the head stock turning just enough for me to get the micrometer in there to measure the OD. As I worked my way toward the headstock I had to move the cross slide out a thou at a time to maintain the constant stem OD. I marked the stem up with a sharpie and used a fine file to knock down a couple of high spots that formed from the different cutter depths. I went back to the 320 emery paper and took the OD to just under .001” over, then switched to 600 and finally 1000 to get a really nice shine. Then I used the round nosed HSS cutter to cut the radius between the stem and the valve top. I then rotated the cross slide to 45 degrees, locked it into place and cut the 45 degree angle where the valve seats into the valve seat/guide. Finally, I used a cut off tool to cut the groove for the retaining clip and started to cut the valve at the thick end, but not all the way through. I used a Dremel cut off wheel to separate the valve from the extra material. Ground the stem to length, then put the stem in the lathe and faced off the top of the valve to size. The valve guide was much easier as it is simpler and the Bronze cuts really nice.
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Yes, the second solution is probably the better one if you have the room. I have an Enco, 9-20. It's OK for small, non critical things, but if you want precision or turn threads, it is a dud. Doesn't even turn LH threads at all. I could put an idler reverse in it somewhere, but the threads, no matter what, are rather crappy compared to the new lathe I just got in January, which is a Grizz G4003G. It does great threads, imperial and metric. Anyway, your problem.Richard,
Thanks for the suggestion. I will google "tail set offset". It would be great if my problems could be solved by an adjustment to the lathe. It is a really inexpensive, small 7" X 10" and I would not be surprised if something were off. I am thinking aloud, I could put a long piece of known round stock between centers and run a dial test indicator in the carriage and run it up and down the rod looking at the top and the side to see if the tail stock is off. Or, I could buy a nice, larger lathe
P.S. Yes, the engine only has two valves, but I am hoping to build more valves in the future. This engine building is fun, addictive and very challenging.
No reason it shouldn't work.I found some guitar strings for 78 cents on Amazon that are .022" in diameter. We will see how it goes.
Had a similar problem with one of mine and used studs with nuts.It is very difficult to get the cylinder retaining screws in, I think I am going to use studs in the crankcase and nuts to hold down the cylinder.
Thanks so much to Dean Williams for an excellent article on small spring making. a subject I am interested in.No reason it shouldn't work.
Since I have several guitars, I always have strings around. The first time I made a spring was using a used guitar string. Last time I made some springs I changed strings on a guitar to get some used music wire.
Between having wire, some steel wool, a toaster oven and this, it's all you need: