Saturday, April 17, 2010

Making a Conoco Gas Truck, Part VI

I’d forgotten about one part that Ragg wanted me to make for the tank truck add-on kit—namely, 5-gallon oil cans. I had no idea what they looked like back in the 1920s, so I did a quick search on the internet and found a Conoco 5-gallon oil can from the late 1920s (as you can see to the right). Perfect!

Conoco Oil Can 300 Conoco Name 300

I did some more research and learned that these cans are about 10” in diameter and about 23” tall. With that information I was ready to start drawing the can in the computer. I do all my drawing at prototype size and then scale the model down to S-scale when I’m all done. The first step is to draw a 10” diameter circle, and then extrude the circle into a cylinder (left-most picture):

Oil Can 1 Oil Can 2 Oil Can 3

Next I added a slightly larger diameter circle on the bottom and extruded it up (middle picture above). Finally, I added some fillets to make the bottom look more like the can above.

Next I repeated the same operation near the top (left picture below). Then I added a truncated cone (middle picture) and the neck of the can (right picture below):

Oil Can 4 Oil Can 5Oil Can 6

As you can see, building a model in the computer is a series of operations that either add or remove material. Most of the steps so far have been adding material, but the fillet operations knock off the sharp edges, so they’re actually removing some material.

The final steps are pretty simple. I made the top slightly domed, and then added the two “ears” that make it easier to unscrew the lid of the can:

Oil Can 7 Oil Can 8 Oil Can 9

The picture in the middle above shows the can after I added some small depressions like the ones on the prototype. These are fairly subtle, so I’m not sure how well they’ll show up on a model that is only about 1/4” tall. Also, the handle that I’ve added is actually solid, as you can see in the right-most picture. But again, since this is only about .01” thick, I’m not sure that will really be noticeable.

Ragg suggested that I not include the handle at all, but I wanted to try. The production mold will include some number of oil cans (I’m not sure how many just yet), as well as three sets of lids for the gas tank on the truck. I have some questions about how well these parts are going to turn out, so I’ve decided to make a test mold that includes just one of each part. I’ll probably start making that mold tomorrow, and with any luck will have test parts before the end of the day. We’ll see how the corrugations and the handle turn out.

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