Well, tonight I’ve had one of those evenings when you discover that your fine, shiny 2-dimensional plans have been complicated by the subtleties of a 3-dimensional world. For reasons that may include the existing frame not being a perfectly square C-channel, despite my best efforts I have an error in my measurements and therefore in the shape of the new frame segment. A very slight error, but one I intend to correct before I go any further.

I noticed it tonight while fitting the first steel side piece (help with finish cutting by Erik Bigelow — thanks, Erik!). There’s a section of the stock frame on which the bed of the truck rests directly; it’s a very short section, and in the new version this straight, flat surface is a lot longer. Unfortunately between the two versions this line is not completely parallel — in my test fit this evening I detected a slight incline in the new piece. If left uncorrected this may cause the bed to have a small but visible tilt to the rear with respect to the cab.

I looked again at my design drawing, and they’re parallel there. So I’m concluding that this error was introduced yesterday as I was modifying the end shapes to mate with the stock frame. Catching this problem now isn’t quite as convenient as if I’d caught it this weekend (the error has wound up in the shape of the steel piece), but it’s definitely a lot less of a problem than if I’d caught it a week from now.

As it stands, I need to verify the severity of the error by taking some more measurements, and with luck I’ll hopefully be able to change how the new and old sections mate (change the cut line) in front to allow me to use the pieces I’ve already made, with some modification. If so, this will have set me back by a couple days.