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This grain will require slightly modified casting hardware. The mandrel will be a foam core as demonstrated in the Monolithic Grain Test. For additional rigidity, and to reduce the amount of foam dissolved, a central support will be included. This might be PVC or aluminum tube 1.000 to 1.050 in OD 19 inches long.
The .dxf of the mandrel is here. 2 of these need to be foam cut. a minimum of 20 . 18.5 inches long. This has been converted to a .dat file here.
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