25 HP Nash

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minh-thanh

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Hi Doug !
Nice engine and runs great.
Congratulations !
Although I have done welding and surface finishing on aluminum, iron, stainless steel, brass, But I am really impressed with how you handle the welds and surface finish, 👍👍👍 .
 

Sprocket

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minh-thanh;
Thanks!
If you haven't tried silver brazing, it's a really good way to join a lot of metals. (but not aluminum)
The braze flows into the joint with little buildup on the surfaces, so not so much to finish.
Also, I think you were considering a sand/bead blaster, and that's another big help for surfaces and paint prep.
Doug
 

Rustkolector

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Doug,
You have an excellent runner. Congratulations. May I suggest that you don't forget to add a gear guard to your engine before too long. I couldn't tell the rotation direction of your engine, but accidents can happen in the strangest ways.

Your carburetor problems with propane are common. A restrictor plate often works well because the needle is working only 1 or 2 turns out. When using methanol carbs without restrictor help the needle needs to be way out on the threads with propane. This normally creates air to leak back through the threads upsetting the fuel air ratio. Depending on the carb used, a fix is to stack small silicone O-rings on the needle threads to prevent air from getting sucked through the threads.

Let us know your generator/alternator thoughts for your Nash.
Jeff
 

Sprocket

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Rustkolector Jeff,
Thanks.
You helped a lot with the propane fuel.
I had looked at your model and the gear cover and thought that looked like a good idea. My gears are behind the large flywheel and so not as exposed as yours but should be covered. I'll work on that.
Rotation direction was hard to figure. Which way should it rotate? or maybe it doesn't matter, but I finally found in "Full assembly, Figure 2"
an arrow that looks like rotation is clockwise looking at the end opposite the gears, so that's how mine rotates. I was sure I'd seen it in the writeup somewhere, but never found it again. That arrow was my only clue.
What I'm planning for a generator is to use the winding from a fan motor and make a new shaft and rotor with magnets and build a case for it. I have the fan motor and the shaft needs to be longer. I figured an aluminum core for the rotor with magnets glued in. I need to do some more poking around in the windings, it was a three-speed window fan. Should fit in a 4" tube for the case, then build up the ends to look like castings.
I'm just beginning on that, so any suggestions are welcome.
Thanks again,
Doug
 

Sprocket

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It was suggested that a gear cover would add to safety around the engine. There are no plans for this, so, I made it up.
At first. I thought I could make the vertical part and mounting tabs from one piece.
IMG_2799.JPG IMG_2801.JPG

But after several iterations of paper pattern, it just wasn't going to work. So, the tabs were added to the vertical part of the cover.
I cut the brass to shape with a scroll saw and finished with a die filer.
IMG_2804.JPG IMG_2805.JPG

The die filer was a project I did a few years ago in an attempt to get more comfortable working with castings. It came from Martin Models and was a
good casting set to work with. Replacement parts are available but weren't needed, and it has been an occasionally useful tool. (The 1/4 scale 5 HP
Galloway castings are still "aging" under the bench)
IMG_2807.JPG IMG_2811.JPG

Rather than have to drill more holes in the crankcase, I used one of the cylinder mounting bolts, and one of the crankcase joining bolts.
Fit looks good with about 1/16" clearance all the way around.
IMG_2815.JPG IMG_2819.JPG
These two are the parts set up to silver braze (no flux yet) and the parts all brazed together.

IMG_2818.JPG IMG_2822.JPG

Last fit check before filing, sanding and bead blast. I had added another handrail on the opposite side to the left of the crankcase doors for "operator safety". I know the step up onto the base is a bit high, but maybe he gets a step stool.
I got a computer radiator with a fan for better cooling. There is only 12 oz. of coolant or so in the system as it is now, and it heats up after a few minutes running.
That's all for now,
Thanks for looking,
Doug
 
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