A while back I bought a box of parts on ebay - a couple of boilers, an engine and engine parts. The engine frame was distorted with age ( I can identify with that). Ed suggested that replacing the frame would be a good project. So, I started down that path and, as projects do, the project grew a bit:


The first issue was the flywheel beeing press fit to the drive shaft. I'd like to be able to remove the flywheel without using a hammer. Drilling a hole through the flywheel for a set screw seemed untidy. Instead, I drilled and threaded a small hole in a short piece of thick walled tubing and soldered it to the flywheel face.

Turned down the end of a piece of 1/8" dia stainless steel rod and threaded it 4-40 for the drive shaft. Left it long to be trimmed later.

Made the main bearing from lignum vitae. Cut about an inch and a half from a pen blank and roughed it to a dowel shape. Then chucked it in the lathe and worked it like brass. It's beautiful stuff.

The rest is detailed in the photos. The drive train is complete so the cylinder, piston and valve plates' next.

Tom

Well it looks lovely and you have good skills! But, wood? Will it really hold up?

In his book "The Steam Launch" Mitchell points out that wood was used extensively in nineteenth century steam engines. Lignum vitae is currently used for both plain and ball bearings. Ebony is not as hard but extremely strong.

However, your concern is justified. I just wanted to do something different. Be interesting to see what happens.

Tom

the lignum turns and files like metal,, will be interesting to see how it holds up as a higher speed bearing.. my navy boat plans show it being used as propeller shaft bearings ,, but using a very long sections that were most likely wet at all times,,

Thanks - I missed that on your drawing. I'll use it on the propeller shaft.

I've read that the resin in lignum vitae acts as a natural lubricant. Perhaps being wet helps.

Tom

I think when I get around to my prop shaft that bearings, seals and grease will be used..

Originally Posted by tghsmith

the lignum turns and files like metal,, will be interesting to see how it holds up as a higher speed bearing.. my navy boat plans show it being used as propeller shaft bearings ,, but using a very long sections that were most likely wet at all times,,

Hardwood has made excellent bearings for thousands of years, at least as far back as fire drills. The problem with wood, however, is that its dimensions and physical properties vary greatly with its wetness (whether due to oil or water), much more so than metal in the heat of a running steam plant. So, you need to keep the wood at a constant level of sogginess to get consistent results.

I'm not worried about the bearing as that's easier to keep constant. I do have concerns about the ebony conrod, though. It looks great but if it changes length much with the absorbtion of hot water and/or steam oil and/or bearing oil, you might have a problem.

Good points.

According to Mitchell the most persistent use of wood was for the long connecting rods on river steamers.

I suspect there will be many upgrades on this project.

long stroke paddle drives ran much slower than short stroke prop engines,, most often they had a wooden core that was strapped end to end with iron..

Originally Posted by tghsmith

long stroke paddle drives ran much slower than short stroke prop engines,, most often they had a wooden core that was strapped end to end with iron..

Yeah, pitman arms were usually strapped. Also, they spent their entire lives at a more or less constant level of humidity just a few feet above the water, and always being splashed when the boat was moving. It's a bit different for a model engine you keep indoors and only run once in a while.

Tom, What you have done looks great! I like the ebony piston rod. It is hard wood and that should minimize the absorption ofwater. Also the tubing idea on the flywheel is good. Nice work on the lathe. What melt temperature solder did you use? What are your plans for the frame?
Ed

Ed,

I used plumbers solder. Tossed the label so I don't know the temperature, but it's not low temp electrical.

I plan to use ebony for the frame. My first cut turned out to be a bit bulky so I'm trimming it down.

I wanted something with fine enough grain to look scale. Koa is a hardwood with an almost fibrous grain. I ripped a strip 1mm thick and used a razor to cut ~3/32nd lagging boards. Rolled the bands from 1/32" brass sheet, I used paper patterns but still came up about 3/32" short on the upper band.

Tom, That really dresses up the cylinder. I assume you pan on mounting the port face on the ebony frame. That should make for a very crafted look. The contrast is appealing. I have used copper and brass to get contrast at times. Waiting to see how this turns out.

It's not assembled. This is just most of the parts in one place.

I'm following the Tubal Cain book on building simple steam engines. It says beginners will make each part 2-3 times. That's about right. Some of these parts are flawed, but I wanted to go all the way to assembly in order to expose size and alignment problems.

Now I can start on pass 2.

Tom