I believe there is a mistake in the chart above. The U.S. equivalent to 8BA should be 2-56. Very handy chart. Thanks packrat. Bob
Updated the .txt file with the change to 8BA. Thanks again packrat.Quote "I believe there is a mistake in the chart above. The U.S. equivalent to 8BA should be 2-56. Very handy chart. Thanks packrat. Bob"
Yes I think your right, Thank you
Hey - I hope the 10v is progressing well and thanks for the mention. I hope some of my videos will be of help too.My first project is going to be a Stuart 10v. After checking out Keith Appleton, TinkerJohn and Andrew Whale thought I'd give it a go.
No machining skills to speak of. Always wanted to do this and have finally started.
Here's a couple picsView attachment 120005View attachment 120006
Gunnar,In my 30 + years of being a Machinist I have run "American Lathe Co" Machines they were all very heavy duty machines and I wouldn't mind running one now. As far as them being worn out, I remember a lathe I ran that was a 20" X 24' old Cincinnati tray top that the ways were so worn at the headstock end the the tool would drop .075 in the last 14 or so inches. we/I managed to hold + - .001 tolerance with the old girl. It just takes learning the machine.
I read about the changes that had to be made during the war because American help came. The British had 55deg, rounded peaks and valley threads, the American 60deg, pointed or flat peaks and valleys. Their were other differences so a commission was formed to make nuts and bolts to work for BOTH types and thus have spare parts that would work in either situation. Market Garden failed to test their radios which didn't work and contributed to the disaster. Nuts and bolts that are nominally the same but fundamentally different can lose a war. So I am interested in what you said. I never knew about the recycled armour but it makes sense. Of course they would recycle what they could.Just an odd point. I have a stock of 7BA bolts with 8BA heads, and other sizes, that I bought from one of the Steam parts suppliers in the UK (mail order). - That helps the model look good with "small hex" heads. Akin to the second world war expedient of using BSF hex sizes for WHIT bolts. - saved millions of tons of steel and weight of aircraft etc. - and we never went back afterwards. But it was made possible by the availability of "recycled Battleship armour plate" - and better steels after WW2... than had been cheaply available in the 1920s...
K2
Hey - I hope the 10v is progressing well and thanks for the mention. I hope some of my videos will be of help too.
Cheers!
Andrew Whale
Thanks for the feedback olympic. I really appreciate that.I'm also working on a 10V.
Andrew, I wouldn't be entirely lost without your 10V videos, but they make my project a lot easier for a self-taught fumbler with no technical training. I'm about 2/3 done now, and, despite my numerous fumbles and recoveries, I think it'll actually run when I'm through.
Many thanks for your videos.
Thanks mate. It looks like you are making good progress.Andrew. Great job on your series. Without the likes of you and others I'd be lost.
Thanks again.
I always try to clean up the two smaller ports using a ball end milling tool for smoother laminar flow. This might take some tweaking. the middle port I make sure it is a bit larger than the other two as it has gas that has expanded and needs to be evacuated more quickly simply because the volume is larger. The valve should be timed to take a little longer over the middle exhaust port but a little larger will not hurt. Just make sure the middle valve port is properly centered else you may have probs with timing.Couple quick questions
Notice the port sizes. They are irregular. Will this be a problem.
Flange thickness is also not equal. Will this present a problem.
I used the port center as reference.
Btw. The cylinder has been bored and over all length machined to size.
you are correct about radiusing the edge of the ports, that's not the place you can do this without messing up the timing just as hyou say. However, on the inside, when cleaning up the sides and so on, one can radius one side of the port. It is probably not worth the effort for this type of engine.This port configuration is common to slide valve engines. But carefully dress the long edges of the holes - use a miller if you are capable - or warding files to "Square-up" the holes. Do not extend the valve timing - The valve timing is critical for top performance, however, even un-fettled, the engine will run. The "more perfectly" it matches the drawing the better, but better to do nothing than take off too much metal and spoil the engine valve timing. The valve rod should have adjustment on the length so that is can be centred over the middle port when setting-up the engine. You really need to understand both the port and valve sizes and how they will mate together to optimise the valve timing. The width of the valve that slides across these ports must be wider than the widest port otherwise the engine will "LEAK" steam internally when running and become a "Poor job". Read a book - such as K.N. Harris's Steam engine book to understand valve timing BEFORE you cut any metal to adjust these ports.
Once you have cut these ports wider than the drawing you need to design and make a valve that suits, so it is better to not adjust these unless you understand the valve and port relationship and timing so know what you are doing.
Metal that is on the casting that isn't on the drawing can be removed, but "HOLES" on the part that are not on the drawing cannot (easily) be filled-in. The air/steam isn't really running around the corner significantly on a normal model, so don't radius the edges of the port as this is changing the valve timing. It is turbulent, not laminar, flow, so will only make a difference on a hard worked /high performance/high speed engine. Which this model is not. Square sharp edges are best for the valve timing. DO NOT make the ports wider than the drawing, whatever you do.
I hope this helps?
K2
Before you order it, call the peeps you got it from. they should simply send a new one. There should be no trouble, as it is defective.Richard, think I'm going to order another cylinder casting.
Steamchick. Ah yes. Lap, lead, pre admission, admission, cutoff, expansion, exhaust and compression. Lots going on here potentially.
I take good material and turn it into scrap. Having said that the steam ports are way off. The exhaust port is the only one that looks good.
Not going to bother with port repairs. As mentioned going to order a new cylinder casting.
Thanks to both of you for your help.
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