Horizontal Air Cooled Engine

[Tim Clarke]

Very classy given the look of the rest of the engine. And as you say, you can always alter it if you don't like it.

[brian Rupnow]

I've decided I don't care that much for the solid flywheel web. I have an idea that is easy to machine and makes the flywheel action more visible as they turn. I think this will be what the finished flywheels look like.

[J Tiers]

I lke the new flywheel idea a Lot! It keeps the "design element" of spokes, but reverses them, and looks pretty darn good in my opinion.

Great idea, and definitely easier to machine!

[Richard P Wilson]

So you could use small faceplate castings for the flywheels?

[brian Rupnow]

Richard--I'm not sure what you mean by "a small faceplate casting". Anything round and at least a 1/2" thick will work. Don't use aluminum because by itself it's too light to make an entire flywheel from.

[brian Rupnow]

Today was intake and exhaust day. I had just enough brass around the shop to make these two assemblies. I have to go buy some more 1/2" diameter brass rod to make tappet guides and valve cages with. All or at least most of the brass will get polished as I get deeper into this engine.

[Richard P Wilson]

Richard--I'm not sure what you mean by "a small faceplate casting". Anything round and at least a 1/2" thick will work. Don't use aluminum because by itself it's too light to make an entire flywheel from.

I've got a couple of 4" dia faceplate castings, can't remember where they came from, and with the cast in slots they do look like your latest flywheel design. I keep one of them on my desk to stand my coffee cup on, and the other has been fitted with a 1" dia spigot, so I can mount small work on the faceplate, and then hold the faceplate in the 3 jaw chuck.

[brian Rupnow]

The morning was spent cutting out the centers of the brass flywheels on the old Rupnow Engine to give me two nice outer rims for my new flywheels, and cutting two aluminum centers from a piece of 3 1/2" diameter aluminum that I had left over from another project. I still have miles to go before I sleep, but so far things are looking good.

[brian Rupnow]

Today I did something for the very first time!!! Those reliefs in the face of each flywheel are 3/16" deep, and they have a 1/8" radius in the corners. I have always known that there should be radius there. I know the whole tune about sharp inside corners causing stress risers and are more apt to fracture in use. It's just that I never actually did it before. I have about 40 engines running just fine without a radius in the corners of the flywheels. Today I actually ground an HSS tool and machined the radius. The outer brass rims are loctited to the inner aluminum flywheel body (That's why they look dirty--that dirt will all come off with a "clean up" pass in the lathe.) Drilling and reaming the center hole for the shaft is one of the last things I will do.

[Sparky_NY]

To get the flywheels to run true, the center hole would normally be first. Then use a mandrel and turn the rest of the wheel. Doing the center hole last is asking for runout.

[Richard P Wilson]

Which is it? You say that to get the flywheels to run true the centre hole would normally be first. Then you say that doing the centre hole first is just asking for trouble.

Anyway, my usual practice with flywheels is to face one side and the edge at one setting, finishing by doing the bore, then flip over and face the other side. I don't like doing flywheels on mandrels, they are usually quite large and the mandrel to fit the bore relatively slender. I haven't had any problems with run out doing it this way.

[Sparky_NY]

Which is it? You say that to get the flywheels to run true the centre hole would normally be first. Then you say that doing the centre hole first is just asking for trouble.

Anyway, my usual practice with flywheels is to face one side and the edge at one setting, finishing by doing the bore, then flip over and face the other side. I don't like doing flywheels on mandrels, they are usually quite large and the mandrel to fit the bore relatively slender. I haven't had any problems with run out doing it this way.

Good catch, my fingers typed faster than my brain could follow, I fixed it

[brian Rupnow]

The flywheels are finished except for keyways, and I like this new variation on round holes cut in the webs. This gives the flywheels an interesting look, and it will still make it highly visible when they are rotating under power.

[J Tiers]

I think they look quite spiffy!

[brian Rupnow]

Thanks Jerry.---Brian