WELCOME TO THE WORKBENCH SPINCASTER PAGE AT NHSOUTH !
      Left is a 1993 photo of me with my first homemade spincaster.   The light steel and aluminum materials I chose made balance a challenge.   The motor was SCR controlled, &nbspfor 1-1000 rpm.   Above is a spoked hub for old number 1.   I made a pattern in auto body filler, then sand casted in scrap zinc.   I soon abandoned disk molds for a fixed hub and standardized rectangular molds.   The hub was no longer necessary, but balance then became even more of a challenge.
      I used a variety of RTV and heat-vulcanized, natural rubber and silicone rubber products from several silicone rubber compound manufacturers.   In the spincaster, I found much better dimensional stability and much longer mold life when casting with heat-vulcanized silicone molds.   Also, although there have been great advances in just the last few years in silicone mold rubber technology, I do not think RTV silicones have been developed yet that can withstand the heat of molten zinc alloys for more than one or two pours, based on my experiences.   If you are interested in sand casting zinc, take a look in my casting book for refractory recipes, and take a look at the free torch head plans here at the workbench.




      I sculpted this tankard switchplate by adding auto body filler to an old plastic switchplate.   I spincasted this switchplate, using scrap pewter, in an 18 inch diameter RTV silicone mold.   The mold was expensive and awkward.   It had 4 evenly spaced mold cavities, for 4 switchplates.   You can see from the picture that the castings tended to run with cold spots, even at high RPMs.   I clamped the RTV as best I could, with flat aluminum top and bottom plates, but the RTV was rather compressible, and I suspect the molten pewter tended to deform the RTV during the casting.   I think that if I had stuck with the RTV approach, but used smaller rectangular molds, the molds overall would not have deformed as much.   I think this would have led to fewer cold spots and more predictable venting and flow.



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