Monday, June 7, 2010

Making of a Conoco Gas Truck, Part VIII

It’s been a little while since I’ve done any work on this project because work and family kept by pretty busy. Ragg built up the parts I sent him, but he felt that the walls of the troughs were too thick. And they were. I made them .032” thick, but that didn’t look good. Additionally, I had to reduce the size of the oil cans to 80% of S-scale in order to fit, so they looked too small. And to add insult to injury, the reduced-size oil cans didn’t even fit into the troughs. Doh!

So, it was back to the drawing board for some adjustments, and then time to make a new mold. I made the walls thinner (about .015”) and also made the troughs about one scale inch wider so I would have more room for full-scale oil cans. However, I had problems filling the part, as shown with the left-most casting below.

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After a little adjusting, I finally got the parts to fill. First I added a third gate and made the gates a little wider (the middle casting above). That go me closer, but not quite there. So next I increased the wall thickness to .019”, and that finally did it, as you can see on the right above.

Here is a comparison of the before and after troughs:

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The new trough is sitting next to the assembled kit. The thinner walls look far better, so I’m very happy I made a new mold.

The next step is for me to polish the molds for the tank itself. You may have noticed that the curve on the top of the tank doesn’t look completely smooth. Polishing the mold will take care of this. I also have to make a new test mold with full-scale oil cans to make sure they fit, and then it will be time to start producing kits. The kits should be available at the NNGC in St. Louis this September.