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Outside of flask cope and drag (10")
The flask has 4 degrees of taper on each side. It will be cast from aluminum. It will use two pins at each end to help guide the drawing of the pattern plate smoothly from the mold. At opposite corners the flask will have latch mechanisms so the flask can spring open (about 1/4") to allow quick removal of the flask. The taper will allow you to remove the flask and slip on a steel pour jacket. The pour jackets are much cheaper than flasks to build. They tend to help prevent runout between the cope and the drag layers of the mold. The non-latched corners will be bolted together solidly. I am currently have patterns for 10" and 12" sides. These will allow me to build 10x10, 10x12, and 12x12 flasks. I have started 8", 14", and 18" sides but I am not going to complete them until I have all of the rest of the pieces for the flask done. There are 4 patterns for the latches and there are 3 patterns for the (2 pin) pin guides.
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Outside of flask cope and drag (10") |
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Inside of flask cope and drag (10") The next step is to make the follow boards for each pattern piece so that I can mount the patterns on a double sided pattern plate. Because the flask pattern has an irregular parting line the follow board is a little complex to build. The follow boards are built to follow the parting line of the pattern. |
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This is a partially completed follow board. The next step is to wax the pattern with Johnson Paste Wax (release agent). Then the follow board is coated with something like "Bondo". In this case I am using Kindt-Collins "Quick-Bild II". It is a 2-part quick setting polyester resin. After mixing and applying a coat of resin to the parts of the follow board that will be in contact with the pattern, I will press the pattern firmly into place. This will squeeze the resin so that it precisely conforms to the pattern. In about 15 to 20 minutes when the resin has hardened I will be able to remove the pattern from the resin leaving a good mold surface. |
Then, I will create a mold of each pattern piece from castable urethane that will allow me to cast the pattern sides directly on the matchplate. Because of the irregular parting line, part of the parting line will be above the flat surface of the matchplate and part of it will be below the surface of the matchplate.
Finally I will cast the snap flask patterns on to a two-sided matchplate which will then be used to actually cast the cope and drag pieces of the snap flask in aluminum.