Xrad's Stuart Triple

[xrad]

Boiler end plates: First, determine the diameter which is the inside shell diameter minus x2 the thickness of the endplates, plus a hair more. I made a former out of hard oak floor remnant formed on lathe.

Cut out the endplates. I used .065 copper. Too thick for shears, and would not fit into my small plate shear. so had to use the lathe. This required a center bolt hole which will be used for the brass stay threaded lug. Cut copper out a bit bigger than the boiler diameter because you have to form the edge. If you do a nice job cutting it out, you will not have to trim anything after forming. Copper is a PITA to machine so go medium slow rpms with sharp cutting tool. I found that a few drops of tap magic worked fairly well.

Once the copper is cut out, heat it until light cherry red. I focused the heat on the edges that will be formed. Easy to form over hard oak a bit at a time. Took four heat cycles to get the piece perfect. Many little hammer dings which will fill with silver solder. SAnd and egt rid of any rough or sharp edges.

Then I gently pressed into boiler end after fluxing the boiler and the end plate. Silver soldered up well. Need to get near red hot for solder to flow. don't overdo the flux so less runs into boiler.

My torch is a small tip for fine work , but I have it hooked to a bottle of MAPP and a big O2 tank so it just works for the endplates. Nothing new if you have done this all before....

 

[xrad]

Boiler tested and steams to 50psi in 13 min without baffles. Boiler box almost completed.

Citric acid bath test ~2 tablespoons in 1 liter soaked for 10 hours...looks nice.

Vid of burner/boiler:

[ame]https://www.youtube.com/watch?v=tP6ES3Kt7bY[/ame]

Orange flame from one pin hole leak coil #4. I need to improve my brazing skills....

 

[xrad]

9 min to 50 psi with boiler in the box.....

 

[xrad]

Boiler nearly done. If you add ten tablespoons of citric acid to hot water, your boiler will be clean enough in one hour. Rinse inside and out very well.

Components of the boiler base: Outside shell, inside cone baffle, bottom shelf(stainless). The internal cone baffle opens slightly towards the smokebox. This is to allow the heat to expand and flow out towards the smokebox because of the last coil blocking baffle. So there is about 1/4 in air gap at the front progressing to about 1/2 in at rear(smokebox) end. If you hold your hand over the smoke stack, the heat does not come shooting out. it has a more gentle but relatively hot flow pattern. Much heat is contained and therefore transferred to the water by my baffle design.

using harbor freight blow torch. I bought the 29$ version because it had a piezo start. Yep, crap. that lasted until just after the first heatup. Buy the 19$ one. Hooks right up to propane tank. It makes a VERY hot flame. I had it set on med low via handle valve. Too huch heat and all your fittings will fall off. It has a ~2.5 inch dia torch head so not good for small jobs...

Hardwood lagging almost done...

Painted with VHT 900 degree brake caliper paint. It will not take direct flame, which is why the baffle is not painted.

Remade the water side of my pump, now it works great(only one side used now). 3/4 steam piston, 1/2 water piston. There was something wrong with the original internal channels. Even with new balls and seats, it never had any pressure.....If you look really closely, you can just see the edge of a bright spot in the front top of the water pump cylinder. this is a small drill hole for air relief from topside of piston.

 

[xrad]

For any beginner boilermaker like myself, this has been a great project, and not too complicated. I think this boiler is much more efficient than the Stuart and runs better with gas (stuart would be better with the blow torch on parrafin/kerosene).

I think this is now a great match for the Stuart marine twin going into the Tramp Steamer. I have a good duplex waterpump, hand pump, electronics for water level control.

Now to design the water tanks and general layout.....

 

[xrad]

finished the lagging. Overall looks OK. Not the best , but surely functional. Will be hidden by boat structure anyway...

I don;t like philips head screws, but that is all my local hardware store had. Need to find some tiny lag bolts....

I cut the stainless straps on a harbor freight 8 in shear/brake. I tried to cut the boiler box plate with it (.05/18 gauge steel) and I damaged part of the shear. Still works fine for thinner sheet...

There is a 25 cent coin in the last pic for size reference..

Last pic is the harbor freight sander. Ok for hobby use but nothing more. On sale for 60$. Belt top acts like a drum sander which is perfect for the lagging inner curve, and the disc for the bevels. Also sanded the trimmed floor board to the required thickness before ripping each plank off on my micromark hobby saw. Using 120 grit. This floor wood was VERY dense and very hard. Even the dremel had some problems sanding out the holes for the steam fittings. Free wood sample from local flooring store....don't know the species....
No, I don't work for harbor freight, they just happen to carry the tools I need....

 

[Swifty]

The boiler is looking great with the timber cladding.

Paul.

 

[xrad]

Thanks Swifty. I just added the super heater coil and tapped a 3/16 40 fitting for it off the steam dome...will post pics soon.