Re: Information on making and using sand casting flasks


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Posted by Jim Clary on October 11, 19100 at 14:31:19:

In Reply to: Information on making and using sand casting flasks posted by John Flanagan on October 07, 19100 at 11:39:05:


A flask is simply 2 matching boxes with sides only. The top box is called the cope the bottom box, the drag. Usually the drag has 2 right angle flanges centered on the outside of each end with fixed pins extending upward 3 or 4 inches with the cope having corresponding flanges with matching guide holes to receive the pins.

A flat "pattern board" (usually of very good grade thick plywood for stiffness or of aluminum) is then sandwiched between them to serve as a platform on which to place your pattern before ramming up the mold. This places the pattern, more or less in the center, vertically, of the mold. If you are using a match-plate, which is a pattern board with the pattern, gates, and runners permanently attached it is placed in the same position.

Once this assembly is made, flip the whole mess over so the drag is on top, dust with parting and ram it up first. After striking off the top surface of the sand even with the sides of the drag, place a �bottom board� (just a flat board that covers the entire drag) on the drag and flip it back over again. Now your half made mold is upright like it will be poured. At this point, if your pattern has a completely flat base that you placed against the pattern board when you rammed up the drag, just ram up the cope. If your pattern has contour on it�s base side that must be followed, pull the cope, remove the pattern board, clean out the sand to reveal the correct parting line of your pattern and replace the cope, dust the entire surface with parting and ram up the cope side of the mold. This done, pull the cope off and remove the pattern board and pattern and you�re ready to cut gates, runners any risers and the spru.

Gating and risering could take up a couple of books. Things like configuration of the casting, type of sand, alloy, cross sections of the casting, pouring temperature, etc, etc. all have an effect. If you have a particular situation in mind I could be more specific.

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