Casting the Flywheel

Making molds for the steam engine castigs
  • This is the beginning of making a mold for casting the flywheel for the engine. This block is a leftover from a mold of a previous casting of an iron plaque. The material is "quick-set" casting sand that is made up of casting sand and a special epoxy binder that gives it properties very much like sandstone. The wood dowel is used here to "drill" a hole through the block.
  • The  block is now right-side-up. By rubbing and turning two blocks together both surfaces were ground flat. The dowel centers  a homemade "fly-cutter".
  • Here the rim cavity for the flywheel is scraped out. The set up is in a drill press only to hold the cutter which was rotated by hand to scrape out a square-bottomed circular ring in the surface.
  • This is a plastic template that was used to accurately scrape out the form of the spokes. The scraping tool is at the upper right and was ground to give the spokes an oval cross section. The template spokes were cut on a milling machine.
  • The fly-cutter's cutting "bit" has been re-welded a bit further out on the handle. Here the “runner”, a path for the molten iron is scraped out. The spoke shapes have already been scraped out. The index pins near the corners assure that the two halves of the mold are aligned.
  • Here are the two halves of the mold ready to be assembled for the pour. The pouring cup seen at the left will be attached to the top half of the mold and will be a funnel for the molten iron. The runner is still to be scraped into the wheel rim in the upper half of the mold.
  • The cooled mold is ready to be “shaken out”. The sprew and riser are seen at the top of the mold. Steel banding tape used to hold the mold together under the pressure of the molten iron has been cut. The remnants of other molds are also in the wheelbarrow.
  • Here the mold has been parted.
  • The part is “shaken” out. In commercial foundries the molds are intended to be used within minutes so they use a binder that makes the molds quite loose and free. Parts can be literally shaken out of the mold as they are carried along on a vibrating screen conveyor.
  • Further progress is made in relieving the part from its “sandstone” entrapment.
  • Here the casting has been removed from the sacrificed mold.
  • The part is ready to be cut from the vents and runners. The mold marks are seen around the rim of the wheel. The rod looking elements are vents that were “drilled” in the mold with a piece of heavy wire. The surface texture is a result of the way the mold was made. Had it been made with “rammed” sand it would be very smooth. This part will be machined anyway so the surface texture is unimportant.