Using some 2×4 pieces, I completed the pattern boxes for the knife patterns that we made on the desktop cnc. This is good because it gives me a chance to mention wood sealers and my experience so far trying various paints. First, let me direct you to a common source for these supplies (at some point I hope to have a longer list of suppliers) at Freeman Supply. They have a nice catalog that you can search and find all sorts of supplies which also indicate the commonly used products in making metal castings. So, the top choices that are possible are Lacquers, Epoxies, Urethane, and Shellac. If you are finishing a floor or furniture there are some nice articles that discuss the differences between these products. The coatings have different amounts of protection, shelf life, ease to sandpaper, tolerance to heat, etc. However, we have one additional twist to the average need to protect the wood surface. In our lab, we use a phenolic urethane coldbox binder system. So, we can use any of the coatings but particularly the urethane tends be more difficult to protect and return to the original finish. For now, we are using a clear Lacquer to coat the patterns and we’ve seen pretty good results on other patterns. The picture of the boxes that I made and how they look after the first coat of Lacquer is below.
Our next step is to pull a couple molds from these pattern boxes to see if the geometry fits the way we expect. If everything goes well, we will try to cut a temporary gating system and pour the next time we are melting down (likely friday, cast iron). Making these knives of cast iron is not the correct final material but we pour cast iron often and it’s a good material for checking out the geometry.
Dr Monroe Thoughts 