Small Boiler

[editor@glue-it.com]

I've literally been back to the drawing board for the miniature traction engine to work out the detailed design of the next few parts.



The firebox is a challenge, but feels like I have a reasonable way forward.

The engine feels a bit more tricky, plan was to create a bracket on the boiler that is brazed in place and the cylinder bolts to it, just not sure if I should use brass for this due to corrosion?

[thehomeengineer]

Hi
I have added a link to my boiler I made to L.C. Masons design which might help. If you plan on steaming I would try and keep to a all copper construction and the boiler bushes made from bronze. I made the stays from copper.
Practical Engineering
Practical Engineering
Practical Engineering
The Home Engineer

[editor@glue-it.com]

Hi Home Engineer, great website and lots of information. Will have to have another look at the cylinder block and mounting to the boiler. My issue is the scale 12mm bore and stroke. Boiler is 1.75" in diameter and so quite hard to make exactly scale, but might have a go. Must admit that I hadn't realised that the bolts go through the boiler shell for the cylinder mounting. Thanks, Nigel

[editor@glue-it.com]

Just been trying to pull together reference material around dezincification of brass and to get a summary together, basically use Phosphor Bronze for all bushes and boiler fittings.

Conditions that can make leaching worse are:
1. Slightly acidic or slightly alkaline water
2. High levels of chlorine in the water
3. More than 15% zinc in the brass alloy
4. Low flow rates and low levels of aeration
5. Relatively high tube wall temperatures

The general consensus being "why did you even ask about using brass fittings"

[editor@glue-it.com]

I had some real fun machining the hole through the firebox on the rotary table. It was all setup after doing the outside edge and just thought why not??



As you can see in the next image, the intention is that the boiler is a simple cylinder and the end sits in the firebox. The boiler has 7 flues for the hot gases to flow through to the smokebox.



I have a few videos of the machining processes

[editor@glue-it.com]

I silver soldered the mild steel boiler together



and then cleaned it up



Quite a lot to do though still on the miniature traction engine.

[editor@glue-it.com]

What is it about model engineering that makes us all sit with a beer and gaze at what we've made?



What am I going to do when it's complete?

[mklotz]

...What am I going to do when it's complete?

I faced the same problem with my collection of engines.

I take them around to local middle schools and provide a one hour informal (kids sitting on floor) talk on the evolution of prime movers from early atmospheric through proper steam, a detour to Stirling, and then on to steam electric generators. We talk about belt drives, reversible engines, steam pumps, and other facets of the emerging technology. Almost every aspect of the talk is a discovery for the kids; they've never heard of steam trucks and steam rollers.

The kids love it and they get to "help" me open and close valves, lubricate bearings, and use blowpipes to operate breath-powered engines.

In the interest of classroom safety, a small airbrush compressor doubles for a steam boiler.

Most of the time the teachers are dumbfounded and the kids are enchanted.

[editor@glue-it.com]

A very small block of mild steel forms the firebox door and an even smaller block on top is the blank from which I'm making one half of the hinge



then after an hour or so with the manual milling machine I had the outline of the door hinge



I think this solid version is much better than my rough initial idea of using brass angle - two misaligned holes for rivets doesn't help the look either

[editor@glue-it.com]

The firebox door now has working hinges and a latch, it is so small and I've just had to look at it for quite a while to work out how to make it. Not sure it is scale, but hopefully it will look right on the finished engine, a few more details of the build here



a short video of it working