Paul Jones (06-30-2016)
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 (07-04-2016)
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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