Steam Engine

2014-04-18

Over Spring Break we crafted a piston from a block of Delrin. We ran the engine off of air pressure until we were able to make a boiler to create steam.

To start making it we used a bandsaw to cut the Delrin into a rectangular cube.

We needed a cylinder to fit in the lathe jaws so we used a hole saw on the drill press.

Here you can see the block mounted between the three jaw chuck and the dead center.

Using the Grizzly lathe we turned the block into a cylinder.

On the Lathe we bored a hole with a drill and faced the internal walls to the required dimension.

Using the Grizzly Mill we flattened one side of the cylinder.

Here are some of the drawings we made to plan the design.

This is the piston of the engine without the flywheel.

The crank shaft was a rod with three different diameters. One each for the flywheel, base, and pump wheel.

The pump wheel was set in the shaft with a pin.

This was done in multiple steps on the lathe.

Here is a video of our engine running off of steam in the Woodinville High School Welding shop.

Working Model Version 1 completed 2014-06-09.

Jetboil heater, copper boiler, smokestack, with fill port, pressure gauge, ball valve control, mounted on Plexiglas.

Building the boiler was more complicated than we expected. We received differing advice to solder, weld, or braze the pieces together. In the end we used a combination of all three: TIG welding the copper tube, brazing the smokestack, and soldering the fittings. We used some copper house wire scraps for filler rod and a tungsten tip on the welder with argon for the shielding gas. The TIG welding was hard, and because of our inexperience it left tiny holes that we had to fix. Thankfully we pressure tested the boiler with low pressure air and Windex which readily showed the leaks. You can see the smoke stack was the worst. We actually cut off the top of the smokestack because of the difficult welding. Then there was a pin hole inside that was very difficult to fill. We did most of the work at school in our welding class but one weekend we rented a welder. Soldering was not easy either. We used two butane torches to heat the copper and even then it was barely hot enough to get the solder to flow. The compression fittings were the easiest. We used a couple wraps of Teflon tape on those.

We have a #40 pressure relief/safety valve to install as well as plans for a better platform for the heater and a new boiler. We think we can simply solder everything. Version 1 turns a wheel but we need to decide what it will run. We have received plenty of suggestions for this.

We had wanted to build a steam engine for some time but the impetus came in our AP History class at WHS because for a final project we were tasked with building something that illustrated history. The first steam engine was built to pump water out of coal mines and later spurred the industrial revolution with Watt's version in 1769. Some of our early interests were sparked from seeing a Sterling engine. We made a couple attempts at Sterling engines with wood, aluminium cans, plastic pipes. Those construction materials and techniques were imprecise and yielded poor results. That is when our dad invested in the mill and lathe for us. He has been our banker and technical advisor on this and other projects.