Time for a new Horizontal Hit and Miss engine

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Richard Hed

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Brian- it sounds like, as others have pointed out too, that your settings are off and maybe even your filler rod. It’s best that you do the research yourself, rather than blindly accepting the guy behind the counter. That maybe a good start, but need to know for yourself. Good TIG welding is an art that does need practice. Even if you’ve been doing it for a while and go away from it for any period of time, you loose a little muscle memory.
It’s a whole different set of feelings compared to stick or Mig.
That's right. I am not a pro TIG welder but I have done it enough to like it, I just don't get to use it as often as I would like. So every time I want to use it, I essentially have to re-learn it. However, since I have gotten a new and modern machine, I'm sure to use it more often--still, I needs practice practice practice. I managed to get some stainless sheet and I have a small project using stainless sheet, so I will get to it soon, but even before that, I will bone up on stainless TIGging.
 

Brian Rupnow

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Today I machined and installed the starter hub on the near side flywheel, machined and installed the push-rod mechanism, and almost finished the second most expensive gas tank in the world. It still needs a little cosmetic finishing and then paint and primer, which I will probably get to tomorrow. I was going to take a video of the push-rod mechanism working, but decided that the only person excited about it was probably me.----Brian
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Brian I would like to see the push-rod mechanism, hope that you did take some pictures of it, I like the expression about the fuel tank, think we have all been there and done that, Engine really looks great, Joe
 

Brian Rupnow

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Today will be the day to make the lockout lever. There is more to this lever than meets the eye. Not only does it have to pivot about a fixed point, it has to hold a compression spring to hold it away from the valve lifter rod. When the governors reach a certain speed, the governor slider forces the lockout lever to pivot, compressing the spring, and making the end of the lockout lever latch under the pushrod to keep it from releasing the exhaust valve.
 

Brian Rupnow

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Today I finished the million dollar gas tank, painted it, and drilled and tapped the frame base for two #8 shcs to hold it in place. A 3/8" hole was drilled full length of the baseplate to accept the long line running from the gas tank so no gas line will be visible.
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raveney

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Time to back away and take a fresh look.--I have so many pin holes in this gas tank that I have decided to start over again. This time around I will use a piece of rectangular tubing with the ends J.B.Welded in place. Only the filler neck and the discharge pipe will be silver soldered into place. This is a formula I have always used in the past, and it has proven to work well and look good. I hate to do this, but until I have a better grasp of using my tig welder I think this is for the best.
Hello Brian,
Sometimes one will chase their tail following good advice. I too struggled with attempting to use TIG building an small scale fuel cell. Watched many dozen videos and learned a great deal.

As an engineer, you may appreciate the scientific approach of listing the variables and only changing one at a time to determine the best solution. Please know that I have full confidence that you can accomplish this, as we have witnessed you overcoming numerous challenges. I have a list of variables that you may chose to review. For me I needed to use a higher argon flow on my setup. I think that outside corners are the reason why. For the thin walled tank, autogenous welding and lapping the corners may give you a better result. I experimented/practiced on many coupons before getting any reasonable parts.

Welding Machine Settings
  • DC Electrode Negative
  • Amperage (1 amp per 0.001”)
  • Pulse off
  • Gas flow 20 CFH Pure Argon
  • Pedal control
  • Turn fan away from work
  • Grounding to part or table
Material Preparation
  • Use dedicated flap disc
  • Remove all mill scale inside and out
  • Use dedicated wire brush
  • File saw cut edges
  • Wipe with acetone
  • Fit up
Filler
  • Type
  • diameter
  • Fresh end
  • Wiped clean with acetone
  • autogenous
Torch
  • Cup size
  • Gas lens
  • Tungsten type
  • Tip angle and grinding technique
  • Stick-out distance (same as cup ID size)
  • Electrode diameter
  • Cut off contaminants if dipped
Technique
  • Electrode to material distance
  • Angle of torch to weld
  • Backing
  • Travel speed
  • Hand support
  • Tig Finger
The part circled is a good use of coupons to practice edge, fillet, lap and outside corner. Please note there were lots of other scrap parts. On carbon steel tube the mill scale can be very difficult to TIG weld and achieve a leak tight result. The pipe fitters at work often discard the flap discs and use new ones as they break through to shiny metal. You may consider using cold rolled 1/8 sheet instead. The thicker material will allow tapping the feed tube into the side as I did with the tank below.
practice.jpg

fuel cell.jpg
 

Brian Rupnow

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Today, the gas tank has been painted and installed. I think I'm down to the carburetor and the governor. I have had a few more thoughts on the governor, and today I hope to get them designed. The governor works fine as it is, but I think I can rearrange things a little bit to cut down on the headroom to keep it farther away from the connecting rod.
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SteamChEng

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Brian, I am watching with great anticipation as things continue to come together. It is a beautiful machine and shows your skill and care! I'm looking forward to the running video!
 

Brian Rupnow

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The small change to the governor works really well. With the governor in action, the governor weights clear the con rod, and that is all they really have to do. This is one of those small changes that I can't really even show you. I am putting up a drawing with a couple of cross sections thru the camshaft, showing the governor "engaged" and "not engaged".--You will see that in either condition, the governor weights don't extend beyond the collar which they are attached to.
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The following is a small detail in Brian's design, but may help to elucidate the general principle.

Briefly, the new clearance bevel on the weights has removed some mass that was counterproductive anyway.

Consider the right hand weight in the right hand diagram. The centrifugal force on that weight is acting to the right.* So the force acting on any-part-of-the-weight-that-in-the-diagram-is-below-the-pivot-point is tending to rotate the weight anticlockwise. However, those parts of the weight above the centre of the pivot are also subject to the same rightward centrifugal force, and the moment of force on them is tending to rotate the weight clockwise. So for optimal design one would remove as much as reasonably possible of the mass above the pin.

*(I know this is not strictly correct.)
 

Brian Rupnow

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Today I will have a go at the carburetor. This design is very close to the design that Malcolm Stride used for his Lynx and Jaguar engine, but the throttle has been removed, as the rpm of a hit and miss engine depends on the hit and miss mechanism to provide the speed control. The throttle bore is always in a "wide open" condition.
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Brian Rupnow

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Very little accomplished today. I did machine the main body of the carburetor, which is actually made from two pieces silver soldered together. I will make the rest of it tomorrow.--In other news---We had our first snowfall of the winter today. Not a lot of accumulation, but enough to cover the grass in our yard. I would have been just as happy if it never snowed---ever!!
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Brian Rupnow

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It has not been an auspicious morning!! I machined the rest of the parts for my carburetor, but broke off an 0.031" diameter drill in that very small (0.079") protrusion on the part on the left hand side. I can't get it out. My machines are not "precision" enough to try and carbide the broken drill out. I now have to decide just what I'm going to do next. The local hobby store doesn't have any brass tube in a size that would help me out, and I don't have any more 0.031" drills.
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Hi Brian, at first I liked the simplicity of this... then looked closer. So maybe you have resolved the issues I shall mention... or will resolve them if necessary.
#1: It looks like the needle is entering a metering hole that has been drilled through the wall of a circular passage. The sealing seat of the hole that the needle enters will not be a perfect circle to seal - if that is ever needed - and will it close off the fuel adequately to stop the engine - if ever required?
#2: The venturi if formed suitably by the taper of the inlet tract (bottom of the drawing). So I wonder "why?" you have what appears to be a smaller hole at the choke of the carb instead of the ore being parallel? - If you think you need a further venturi at the carb itself (Based on your experience of many small carbs - I have no experience worthy of comment!) - then I would have made a smoothly tapered inlet into this light blue cross piece, instead of a turbulent "step" from the tract diameter of the green part into the choke shown in the blue part?
#3: On the only carb I have made of this design I used a ground long tapered point from my drawing compass set (dates back to the 1960s). It worked fine without a reduction of diameter at the choke of the carb itself, but I did arrange a rotating bar with semi-circular notch to act as an air throttle, just on the "outside" of the fuel mixing point. (The engine only ran for a minute before it lost compression (cracked cylinder!), so cannot say it was a good carb design or not!).
Anyhow, I wish you success with this one!
K2
 

Brian Rupnow

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These carburetors work on a venturi principle. Any reduction of the passage which the air rushes through, will create a pressure drop in that area. The blue fuel rail tube has a hole through it slightly smaller than the main carburetor air passage at that point, so creates a low pressure area at that point. The fuel rail is drilled so that all of the internal holes are perfectly round. Raw gasoline is sucked into the right hand side of the blue tube because of the low pressure. the round red needle can be screwed into the discharge hole in the blue tube to meter the amount of fuel which rushes into the carburetor main air passage. as soon as any gasoline enters the main air passage, it is picked up by the moving air stream and atomized, then sucked into the cylinder to be burned. There is no choke at all on this carburetor.
 

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