25 HP Nash

[minh-thanh]

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, .

 

[stanstocker]

Greetings!

It's been a pleasure following this build, congratulations on getting it running so well. It looks great. Thanks for all your effort to share the build with us.
Stan

 

[Sprocket]

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

 

[Sprocket]

Stan;
Thanks!
I keep learning from people and projects here, so it's nice to show what I've learned.
Doug

 

[Rustkolector]

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]

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]

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.


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.


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)


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.

These two are the parts set up to silver braze (no flux yet) and the parts all brazed together.



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

 

[kuhncw]

Doug,

Nice design and well done. Looks great on the engine.

Chuck

 

[rcflyer]

It amazes me how you do that! Your work is truly magnificent. One day I will see it in person.

Steve

 

[Sprocket]

rcflyer,
Thanks, I'd like to show it to you.
Different models, different materials, different techniques, but it's all kinda the same.
If you can make things, you make things and figure out the differences.
Good thing mine don't have to fly!
Doug

 

[raveney]

To maintain the distance in the throws, I'd made some little "T" nut pairs to clamp in the spaces.
then turned the ends to 7/16"

I have machined all the crankshafts from one piece because I thought drill rod would harden after brazing and I wouldn't be able to machine afterwards. What's the secret? Do you anneal it again?

 

[Sprocket]

Raveney,
I think when you heat the drill rod and cool in air it is annealed. I've never had a problem with it being hard to cut. My first try was not straight enough, and I couldn't get the bend out, so on the second one I used 1/2" for the main shaft, and then finished to 7/16". That second attempt came out much straighter than the first. I just made the middle bearing to accommodate the 1/2" center section. Even heating should help prevent warps.
If you don't quench it, it shouldn't be hard.
Doug