Oscillator Cylinder Pattern

[Sanjay F]

That finish looks really nice, well done on a successful casting 

[CI]

Very nice cylinder !
I wish more folks would make their own cast iron parts.
This is a good example of what can be cast without a whole lot of effort (once you get set up).
.

[vtsteam]

Thanks Sanjay, CI. 

I wanted to try out making a pattern with hole saw plugs. It's sort of taking on a life of its own, without actually planning to build an engine. I didn't think I was going to cast it this winter, but here we are. Still wasn't sure I'd build anything but I kinda wanted to clear out the bore to see how good the iron was. Did that. Then this afternoon it seemed like I ought also check how good the metal was in the valve face. Turns out it was as good as the rest. Seems like I let this thing go for a day, and then something says, hey, do this. And each time I do, it gets a little closer to being an engine.

[PaulR]

Excellent! Was it as good to machine as it looks? It definitely needs to become an engine of some sort...

[vtsteam]

Paul it's really nice stuff to machine -- I mean in terms of cutting. Cast Iron makes black colored crumbly graphite swarf so, not clean, if that kind of thing bothers. I don't mind.

One great advantage for CI cylinders is that they have some self lubricating properties even dry. This is particularly valuable in hot air engine piston cylinders (not displacer cyls).

My main interest is hot air, not steam. But I will try to make this into an engine, having got this far, unless I goof up on it. I have no design for this-- it was just a by eye pattern with nothing drawn, and I have never made an oscillator before. This is a pretty big one, so I guess we'll find out if I get through with something working in the end.

[vtsteam]

I guess the next major components needed would be a piston, and end covers for the cylinder. I don't have any 3" diameter stock in steel, so I probably will have to cast the covers. I do have some previously cast rod larger than 1-1/2" dia, so the piston could come out of that.

The biggest lack would be a flywheel. I'm guessing something like 8" dia. would be right. I have never cast a spoked flywheel. Although I've done lathe faceplates that large, and a 4" dished spoked lathe handwheel.

It will be a definite learning experience making a big spoked flywheel pattern. Anyway, for now, I'll concentrate on the end covers, and piston.

Suggestions welcome from all, BTW.

[PaulR]

I hadn't grasped just how big the cylinder is, looking forward to seeing this beastie progressing.

I made the piston for my hot air engine from cast iron and have made a few other parts from it in the past, nice to machine but messy. Did you see my post about the 100 year old pig which someone kindly pulled out of the local canal for me? I have enough cast iron in that to last me for a very long time

[vtsteam]

No I missed that about the pig, Paul -- where is that?

[PaulR]

Reply #7 here: https://www.modelenginemaker.com/index.php/topic,12584.0.html

[CI]

You can carve a spoke, turn a hub and rim, and cast multiple spokes.

https://www.modelenginemaker.com/index.php/topic,12328.msg292288.html#msg292288

or

You can use the myfordboy method for making a flywheel pattern.

<a href="https://www.youtube.com/watch?v=-sQCJ6rv54s" target="_blank">http://www.youtube.com/watch?v=-sQCJ6rv54s</a>


This was my first casting attempt, which was a test to see if I could make a pattern half for flywheel spokes.

https://www.modelenginemaker.com/index.php?topic=12675.new#new

.

[vtsteam]

Reply #7 here: https://www.modelenginemaker.com/index.php/topic,12584.0.html

That's pretty cool, Paul! I love recycling repurposing. And a really nice find. 

[vtsteam]

CI Thanks for the references and pics of what you've done. Nice curved spokes! I want to do straight ones for this one. I haven't watched the MyfordBoy video yet, but will tonight.

[vtsteam]

I decided to continue making an engine out of the cylinder by repeating the hole-saw method of wooden pattern making with two identical cylinder cover blanks. Besides adding material for the usual external bosses, I left them long to serve as chucking pieces. I'm also making these stems removable via pegs to serve as loose pieces when molding. Makes it a lot easier than casting them sideways with a false cope.

Likewise, to make molding the original cylinder easier, I probably should have made the pattern split with pegs -- my main difficulties in that casting session were due to a too loosely packed false cope.

I think I will split that pattern in future. I've done that before, after the fact. Normally it's easier to make a split pattern by doweling or screwing the original wooden blanks together along the pattern centerline before carving or turning, then separating them afterwards. But with the hole-saw method I'm working on, that isn't practical. But I can split my cylinder pattern by sawing with a Japanese pull saw along a marked centerline, afterwards.

The covers, so far:

[CI]

That is a cool method to get round shapes !
.

[vtsteam]

Thanks CI!

One nice feature is that the hole sawed blanks all have 1/4" pilot holes in them, so you can string them together like beads on a 1/4" dowel. They are all perfectly concentric because of that, as well. And it's easy to make pegged loose pieces for that reason, too.

Tip: they are a tight fit on a dowel, so I found enlarging the pilot hole with the next drill size up makes them much easier to slide if connecting more than two together.

Making these patterns doesn't take the same skill as hand turning on a wood lathe with turning tools, particularly for cheeked patterns. And a hole saw is very fast compared to setups and tool movements on a lathe.

Tip #2 If anyone does want try this, remember the plug will be smaller than the marked O.D. of a hole saw by about 1/8" so don't make the mistake of buying one the wrong size for what you need.