Hi John, I wanted to say how much I enjoyed the whole log, but the particular parts that were learning lessons. That deal with the end mill and the pulley is great, I made a tubing bender for motorcycle frames, went through three different iterations, making "pulleys" for each, the hard way, and since I will be making another version, having learned from this last, I will be making another "pulley" with an inch groove, but the groove will be more accurate, and far easier to machine, using your method. I also questioned the thinning of the burner cover, and have made a similar burner, only out of 3/8ths copper pipe, for the smaller engine, and used a .046 drill behind a #1 center drill, drilling some .310 deep, and when I cut it off, faced it, and got it all cleaned up, the back side looked dead on target, and there are obvious signs of drill wandering in the .300 thousandths of drilling, so I will be making the next one much thinner, your instincts being dead on right. Not enough wandering to make it not work I expect, but I'd rather the pattern be accurate on the burner face, and I expect the length of the holes will have some effect on the direction of the gases coming out to burn. I will be testing it out shortly, and will post the results on the log I started just for gathering ideas and brain storming on these engines. I'm hoping that will stay around a while, and let more people start with a simple engine, and not have them, as you point out, sitting on shelves not running, when it generally is a pile of niggling details together stopping it, and not just one big error. I don't have a ready made orfice so I will be trying out my own set of small jet drills, and hopefully will find one that works well with the pipe size and the nineteen holes in the burner head. Again, a very well done and easily followed build log that has been very informative. Wish I could still smoke
I miss it a lot, even twenty years later.
Cheers, Jack
