Re: Drawings and accuracy was Re: Mainline Modeler ?????

Schuyler Larrabee

Third and most important is that the original draftsmen
weren't immune from
human error. I'm presently trying to reconcile a cross
section with the
dimensions extracted from the side elevation and there is a
difference of
several inches in the placement of some important components. These
differences are big enough that they can't be explained by
distortion in the
scanned drawings.


I did drawings of an ERIE steam locomotive. It was very late one night when I was checking
dimensions to be sure that everything was what it should be when I came up against an error of a
couple of inches. It was pushing 3 AM (and I had to work the next day .. . ) when I came to
understand that the original draftsman had made an error; he'd drawn the boiler 3" too high above
the frame. With CAD, it was maybe 30 seconds work to correct it. But it took me hours to
understand it.

I also made artwork for a t-shirt by taking a drawing for a turntable and making the full circle
plan image of it. Of course, the original drafter had only drawn about 55% of the plan and
elevation, the rest was simply understood to be mirror image. But when I flipped the image to get
the other half, something was wrong. 98 years after the fact, I found his drawing error, wherein he
had put the centerline of the table 12" too far away from the end he'd drawn.


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