Plans: HMEM’s EZ Build Engine

You won’t need a mill to make this nice looking steam engine that was designed to be an easy-to-make project to teach basic machining skills to beginners.   The free plans come in both US and metric versions and they include 24 pages of helpful instructions.

It was designed by members of the Home Model Engine Machinist (HMEM) forum, led by “black85vette,” who proposed designing a very basic and easy-to-build engine that could be built by someone without a lot of experience or tooling.  What they came up with is an engine that uses tooling you probably already have or you’re going to need someday:

  • Lathe with a 3-jaw chuck
  • Parting tool
  • Hacksaw or band saw
  • 4-40 tap
  • 1/4-inch reamer
  • 1/2-inch reamer
  • Some drill bits
  • A drill press

You’ll also need some measuring/lay-out tools, a marker or lay-out dye, a center punch, vise and some files.  And a live center if you decide to make the flywheel from flat stock using the “special” technique.

The engine was also designed to be inexpensive to build and use materials and fasteners that are easy to obtain and easy to machine.

  • 1/4 x 2 x 10-inch aluminum flat bar
  • 3/4 square x 4-inch aluminum bar
  • 5/8 diameter x 2-inch brass rod
  • 1/2 diameter x  2-inch brass rod (you can use 5/8-inch brass rod and turn its diameter down)
  • 1/4 diameter x 4-inch rod in mild steel or brass
  • 1/4 x 1/16″x 6-inch flat brass
  • (15) 4-40 screws x 1-inch long (some of these will be cut to length)
  • You’ll also need aluminum or brass to make a 3-inch flywheel.  You can either use a 1/4-inch thick disk cut from 3-inch round stock or make it from a piece of 1/4-inch thick flat stock that’s at least 3-inches wide.  You’ll use an interesting technique if you make it from flat stock.  It is described in the instructions and I’ve also written about it.

You could also use steel for the flywheel but you’ll need a little experience to machine it.  One of the group’s objectives was to use materials that are easy to machine which is probably why it wasn’t listed as option.

The 24-page construction manual is well written, profusely illustrated and provides step-by-step instructions with lots of helpful tips for a beginning machinist.

Download the Plans

  • From HMEM (There are two versions.  You want this one, the “13Nov09” update.)

4 thoughts on “Plans: HMEM’s EZ Build Engine”

    • It’s a model steam engine, although for safety reasons most engines like this are run on compressed air. The larger square block is the cylinder and it has a piston. The other is the valve block. The valve block opens to let steam/compressed air into the cylinder, which moves the piston and the flywheel connected to it. It then opens at the correct time to let the steam/air out before it starts the process over.

      I haven’t built this engine. But the group who designed it put a lot of thought and work into it and I think it’s an EXCELLENT project for a beginning machinist.

  1. I have built this engine and it runs nicely on 3-5lbs air pressure. I don’t quite have the lungpower to run it, but my grandkids can.


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