First things first: I absolutely recommend that you not build this boiler. This page is being provided for
informational purposes only. During
the course of my experiments with model steam engines, I did build a boiler
based on these concepts. I am simply providing a review of the design and my
observations of it’s operation. If you are intent on building a boiler for
your model, I’d recommend that you review the plans in some of the books
available through “Home Shop Machinist” or their publisher, The Village
model steam engines appearing on these pages will operate just as well, and much
more safely, on compressed air. This does not imply that using compressed air is
foolproof. An engine that is poorly constructed and/or run on too much pressure
may “blow up” and scatter metal projectiles. When test running our motors,
we always use a clear plastic Lexan scatter shield (the kind used on metal
cutting lathes……available through Enco, Broadhead-Garrett, etc.). It goes
without saying that we always wear safety glasses in our lab.
Use a standard size steel soup can that does not have a “pop-top” lid
(do not use an aluminum soda can). Choose a can that contains a light broth (no
noodles, etc) since you will have to drain all the product through two small
Remove the paper label
Drill two small holes (about 3/16 “) in the top near the edge and about
1” apart. Drain the product and flush thoroughly.
For “outlet” and “pop-off” connector, use two pieces of small
metal tubing, about 3” long with about 3/16" OD. Bend gently as shown.
Solder into the holes as shown. For the metal tubing, I used automotive brake
line (from a junk car). Brass or copper tubing (from a hobby shop or hardware
store) would also work.
Cut a 2”length of rubber tubing (3/16” ID automotive fuel line hose
would work well) and plug one end tightly with a machine screw. This is the
“plug” for your pop-off connector……effectively, this is the safety
valve. Slide the plug over the pop-off connector and apply compressed air to the
outlet connector. Adjust the plug until it just pops off at about 30 PSI (by
“adjusting”, I mean the distance the rubber plug is slid over the pop-off
Construct a sheet metal support (as shown)
Connect a longer piece of hose to the “outlet” pipe (about 12
about 4 ounces of water in boiler and heat gently with a propane torch (not too close to can) until water boils
and steam is emitted from outlet hose……practice holding torch far enough
away from can, so that it just barely produces steam. When you
have mastered this, connect the steam hose up to the inlet connector on the
engine and spin the motor.
Don't let boiler run dry!
Don't let boiler run dry!
Make sure the engine you are powering with steam will already run on compressed
air……otherwise, you might be troubleshooting two things at the same time.