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madjackghengis:
Hi Chris, again, the advise you've got is all good, but in truth, you need do nothing about the length, you can leave .015 dead space at each end, which I would recomend over leaving it all on one end, or you can simply leave the piston .030 thicker/longer and allow it to take up the extra space. The hardest way would be to increase the stroke when you machine the crank, so it has an extra .015 in stroke, and as John said, make notes on all the different things it would effect. You should have enough rod length to allow for adjusting the piston to equal travel and equal head space on both dead centers, or if necessary, add the .015 to the rod length, it should be threading into the cross head anyway, as you always have to adjust the length of the piston rod to set up your dead centers (top dead center and bottom dead center). The rod from the valve eccentric also is adjustable with threads and a lock nut I assume, and the rod running through the valve should have a nut on either end of the valve to set the timing, so if you have to make the valve rod fifteen thous. longer, no big deal. The main issue is you've got the port centered, and everything else is just individuality in your engine, nothing more or less. You can even claim you did it on purpose to get more horsepower, and draw diagrams demonstrating the truth in your statement.
As to machining the valve face, I would bolt the angle plate directly to the table, as you are "stacking tolerances", in clamping it in a vise. As a rule, you will tend to be more accurate, the more you work directly on the table of the mill, and the fewer parts of "jig" between the part being machined, and the table, assuming the mill is fairly accurate with respect to flatness of the table, perpendicularity of the spindle, and more importantly, perpendicularity of your quill travel. Much error has crept into work because the spindle was indeed perpendicular to the table, but the quill travel its self was not. You can test this by putting an indicator in the spindle with your best square on the table, and running the quill down and up, with the indicator against the square. If you are not certain of your square, you can do the same thing twice, once on each side of the quill, and if the reading is zero on both, your quill is indeed perpendicular, and if the reading is say .005 on one side, and .005 going the same direction with the quill i.e. down on both or up both sides, it is your square out of truth. All that said, you will have dead space top and bottom just to keep from hitting when things get loosened up a bit from running, I'd just go ahead and mill the valve face, and use the X axis for reasons stated by Nick I think.
Personally, I prefer castings to billet, as they save lots of metal and machine time when they're right, and in my experience, castings I've worked over the past ten years are substantially better than those I worked on thirty years ago, lots of them come from very high tech controlled atmosphere furnaces, being done with automated equipment, and with better quality original metal and a better knowledge of the ore going into the original foundry. You will note, most people who machine out of billet end up doing much work altering the final profile to more closely resemble castings, and how they make the whole of an engine look. As a final note, when you mill a flat at each end of the cylinder to drill your ports to meet the cast in ports on the valve face, it is worth the time and effort to move the table all around, with a drill bit in, or some drill rod, and ensure the shallow angle you will be drilling, will meet the port as clean and well as you possibly can as you will always deal with "wander" when drilling long skinny holes, but that is perhaps the hardest part of the cylinder operations, and not too hard after all. It's nice to see good workmanship such as yours, and a pleasure to watch it come about. cheers, :beer: jack

NickG:
Yep, apologies Chris for :offtopic:

Bogs,

Thanks, that's good to know as I've been looking at Bruce Engineering ones. As you say, the Anthony Mount ones look lovely but they are bloomin' complicated! I remember seeing him serialise things in Engineering in Miniature and it sometimes took years!

Those castings you bought for both engines look good, I've always been tempted by the Scott Vacuum (flame licker) in the past but since then have made 1 and need to finish poppin so I doubt if I'll do another, even though the price seems pretty good from them. You're right though, the ones they have on display don't really do them justice, they should have gone to town and paid extra special attention to detail there.

I liked the look, and price of the atmospheric gas engine but have just read you really need acetylene to run it and I can't think that a source of small bottles of acetylene is going to be easy or cheap to come by! :doh:

I haven't noticed the stockport engine before which is a vertical flame licker, looks quite nice.

I agree with madjack, that is always the bit I have feared most on a slidevalve engine, drilling the ports - perhaps the reason I've never attempted one, On loco cylinders you usually have a face perpendicular to the valve face which can aid you because you can scribe lines on it and set them vertical.

I had it sussed that I was going to do that on my horizontal mill - clamp that face to the table at the right angle and simply put a drill chuck in the horizontal spindle - but that mill has gone now!!!!! Still, plenty of other ways I guess.

Looking forward to next installment. :thumbup:

Nick

madjackghengis:
As is probably obvious, Chris, I'm living vicariously right now, through your build, but I really want to see you build an engine you will enjoy for years, unlike my flamelicker, which I built twenty years ago, never got running until I was looking one exactly like it on this forum, running, and had to conclude if anyone could make it run, I could. I made two more cylinders, five more pistons and completely modded the valve, and made a new cam and crank assembly, as that was the main error I had made, screwing up the cam.
When the port drilling is to be done, it's a fairly easy task if you go at it right. The big issue is to get enough "flat" milled at the end edge of the bore, and use a center drill to ensure no wandering of the drill bit. I will be using an adjustable angle plate, with the valve face clamped to it, and having determined the angle of the holes leading to the ports by my measurements of the valve side of the cylinder thickness, and where in that port I want the holes to end up, and then on the actual mill, with either the drill in a chuck or a piece of straight rod, which is easier to see than the drill with flutes, and align the drilling by eye as the final decider when I clamp the adjustable angle plate. For the ports on my cylinder, it calls for at least three holes be drilled for each port, so it is a bit more complicated than just a single drilled hole, but I don't know what your plans call for as to those ports. If you don't have an adjustable angle plate, it can be well done with a regular angle plate and some wood shimming or aluminium arranged to get the hole through from each end, and end up inside the port well clear of the face, so as not to interfere with or distort the port, as its edge needs to be clean on each side of each port for good, clean timing. What John said about using old castings rather than making new patterns is a trick of the "cheap seats", and most businesses which operate that way go out of business rather quickly, in my experience. No casting kit I've bought in the last fifteen years or so has been anything less than great on the castings, no blow holes, good meat to allow quality workmanship, and the best metal clarity and proper allowing of cooling, leaving nary a one hard spot in perhaps a couple dozen casting projects, including a couple of cross slides for lathes, a filing machine kit, a couple of kits including a boring head, low profile indexing kit, the Tiny Power Ajax steam engine I'm building, and a few others I've forgotten at the moment. The pictures I saw suggest the Stuart kit is among the top of the line, as kits go, so I expect you have good castings with good metal, particularly with you description of the machining, as you weren't cussing them out, as you would if it were one of the others, not worth the iron cast out of.
I would clean up the ports and get them rectangular with good clean depth and bottoms, sharp corners for timing, and evenly spaced between the two outer ports and the central one, and spacing will determine if you can time it exactly or not. The depthing being even is to ensure you can easily get the drilled holes from the ends of the cylinder, directly into the proper port, with plenty of room to not having the drilling interfere with the port edge at all. The center port is pretty straight forward, just a matter of ensuring clearances, so you don't pierce the cylinder wall with the larger drill bit for the exhaust, quarter thirty two if I remember right. I hope you don't feel like I'm trying to run your shop for you, just want to see a good engine done to your own pleasure and enjoyment. :whip: :poke: jack

DMIOM:
keeping :offtopic:

--- Quote from: NickG on October 08, 2010, 06:06:11 AM ---......you really need acetylene to run it and I can't think that a source of small bottles of acetylene is going to be easy or cheap to come by! ........
--- End quote ---

I don't know if you need it pressurised - but if not, how about making your own - get some handfuls of Calcium Carbide and a cup of tap water and craft a nice drip feed like a carbide lamp?

Dave

Rob.Wilson:
Hi Chris

Looks like your having fun with those castings :clap: :clap: :clap: :clap:

Allot of crackin advice being posted too :bow: :thumbup:

Rob

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