My 24' Launch

[S. Weaver]

Walking beams for the engine pumps ... The continued good work of Kelly Anderson!

[Rainer]

Hello Steve,

can you please give some dimensions?
What diameter you have designed at the axels?

[S. Weaver]

Hi Rainer! Just getting back to you ...

The walking beam axis is 0.618" 4140 steel.
The bushings are 0.625" , probably turned out of free-machining brass, and silver-soldered into the walking beams.
The beams themselves are laser-cut A36 mild steel.
The shouldered link pins at either end are turned out of the same 4140 as the axis. They are turned to 0.437" for the links; 0.375" for the beam pivots; the threads are 3/8"-24.

I have shop-prints of all of this but no CAD or scanner on this computer to show you. If you are interested, we probably could send you a set of prints.

[fredrosse]

A note about shaft bushings that may be of interest, and some experience with the Margaret S main walking beam. The connecting rod small end bushings on the walking beam engine are 0.500 inch inside diameter x 0.5625 outside diameter x 1 inch long. Calculated bearing pressure is about 1400 PSI, which is a high number, as about 1000 PSI is usually quoted as a maximum. When I first put the engine together I used yellow Brass bushings, and they started to pound in just one day, evidently that level of pressure is way too high for a brass bushing. I then made new bushings of Bronze, and these bushings have been in service for three years now, and are still holding up OK.

You probably have bearing pressures that are much lower for your beam and its connected pumps, but I just wanted to mention this experience. Removable/replaceable bushings instead of soldered in place bushings might be considered.

The Margaret S. connecting rod small end bushings are designed for a No. 9 tapered pin that can be drawn up to remove play, as some mechanism to remove knocking on a double acting machine is generally a good idea. I have all of these parts, but used the straight simple bushings so I could get "steaming" as soon as possible. I still need to get a "Round tuit" for the tapered pin bushings installation, maybe this winter the modification will be implemented.

[S. Weaver]

Thanks, Fred. Actually the free-machining brass are spacers. The bushings in the beams contain Nylon 6, a product we have used successfully in small steam apps.

[S. Weaver]

Here's a shot of the floors going in. The intermediate one between No. 3 and No. 4 is the rear bearer for the engine stringers. The center piece was left in while fitting in to keep everything true. Later, it will be cut out when it is time to fit the engine stringers. The mortises in No. 3 receive the lower half of the stringers, giving a purchase for the epoxy joint. Just peeking out past No. 4 is the stern tube.

[87gn@tahoe]

Beautiful work.

[S. Weaver]

Wes, thanks for the encouragement. I'm now entering the cold season of heat lamps and fast epoxy ...

[S. Weaver]

Got out No. 2 floor and frame this weekend. A little more complex with all kinds of considerations from relief for the boiler jacketing above the floor to eventual conduit runs under the side deck. The frames are 0.75" with sistered floors. The curvy support is for a seat. I left a cross spall in place until the deck is on. The holes between the limber holes are for the piping to the forward feed/trim tank.

[Rainer]

Thanks for the pictures. All this helps to widen my personal horizon and to cheer me to do some more woodwork at my boat too. Because my "warft" is under the roof of my workplace, I have no temperature problems during winter.