Casting the Engine Base

Cast iron steam engine base
  • This is the inspiration for the shape of the trim on the base casting. It is a close-up photo of the top of our parlor stove. I cemented a print of the photo onto a piece of flat steel stock and then ground a cutting tool to the shape of the outline.
  • Shown here is the cutting tool in the milling machine making a length of maple molding for the base pattern.
  • Here Jim Williams at the Art Department at the University of Minnesota is tending the "Mulling" machine used to mix casting sand with a special type of epoxy. This mix can be used to make a mold that can be stored for several weeks if necessary.
  • Here the pattern is set in the bottom of the "cope" which will be rammed with the casting sand and turned over.
  • The "drag" is placed over the cope and also rammed with sand. The two are then parted carefully and the pattern is removed. "Sprues" and vents are cut into the cope half and the two are reassembled.   Extra sand is used here to make pouring "cups".
  • The pouring cup and the vent extensions are ready to be cemented onto the mold.
  • After being secured with steel strapping tape the mold will be ready for the pour.
  • The mold is opened after cooling revealing a disappointing defect in the casting.
  • Here the void is exposed in all its fury. It is clear now that there should have been at least one vent in the center of the thin section of this casting. Trapped air prevented the iron from flowing freely into the cavity. Live and learn. The base went on to live a happy life after having the void filled with an "epoxy steel" and finished smoothly.
  • Clearance slots are being milled into the base for the flywheel and the swing of the crankshaft. The void in the casting has been filled.  Click  here  to go back to the steam engine home page for more about the steam engine.