Paul Jones (Jun 30, 2016)
I wanted to share this with you. Back in the days when I didn't have any machines, such as, a lathe, a mill, a cnc router, or a 3D printer, which I still don't have, I made patterns out of wood with just a hand held router and a band saw. While this 1945 Pullman observation is not perfect, in my estimation, it still looks good. The fluting was made with a bullnose 1/8th inch router bit, spacing with different thickness plastic spacers on a jig that I made. The roof shape was made with 1 inch sections of wood. After the patterns of the sides and roof were made, an epoxy mold was made. I made the mold long enough for the round end and a straight roof, which I still use today. My point is, one can still make models without all of the fancy machines. Bob.
Some bubbles occurred in the last pour of the cab, so I added some some relief channels to the upper most part of the mold where the bubbles occurred, so I hope this cures the problem, I will know later on today, and also I have been taping paper, with vinyl caulking, since the tape won't stick to the waxed wood, to make the cleaning of the molds easier, works good. Bob.
Paul Jones (Jul 4, 2016)
Thanks Paul. Just an update. Poured another 15 lbs. of urethane today for another heavyweight side, some parts for the truck, pilot for the cab,**and*reduced a*three part piece for the truck to one piece, starting the mold today. I keep forgetting to tell you this. *I don't know how many of you are using urethane, but if you do, this procedure was recommended to*me by the seller. *Part A, that is the hardener, to keep water vapor in the air isolated from the urethane, after opening, a shot of nitrogen should be shot into the bottle to preserve the hardener and to give it more shelf life. I found out the hard way, without that shot of Nitrogen, the hardener will gel much faster. *The part B doesn't need this step. When they ship it, a shot of Nitrogen is already in the bottle, but once opened, you have to do it again. *The Nitrogen is heavier than air, so it isolates the urethane from unwanted moisture in the air. *Urethane, in contact with air, causes the moisture to get into the urethane and causes air bubles in the urethane, just something that I had to find out the hard way.*Bob
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