In Projects, Shop Blog, Techniques

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Now that I had my thick-walled hollow wooden form built, I had to draw the curved outline of the finished shape onto two adjoining faces of the form. The process is very straightforward.

The traditional, age-old method for scaling up a drawing was to first draw a grid of squares on top of the scaled drawing, then take a sheet of paper or other surface large enough to accommodate a full-sized drawing and lay out a larger grid of squares. In my example, I would begin with my 1/4-scale drawing and superimpose on it a grid of 1/4" x 1/4" squares. I would then take a sheet of paper (or plywood for that matter) at least 16" x 32" and lay out a grid of 1" x 1" squares on it. I would then meticulously replicate the content of each square in the 1/4-scale drawing in the corresponding square of the full-size drawing. After I had transferred all the lines, I would then fair my curves and I was good to go. A pretty tedious process!

Alternatively, it was my practice for many years, if I needed a scaled-up drawing, to take it to a blueprint shop and pay them a nominal fee to make a full-size drawing—there was a place conveniently located in my town, less than a mile from my house. But that business is long gone, made obsolete by digital technology. So when I needed to enlarge my scaled drawing, I made a scan of my drawing and took the digital file to a Digital Imaging service that had a large-format inkjet printer. They simply enlarged the digital image to output at the required dimensions and printed:

I carefully cut the outline of the base with a pair of scissors and glued it onto a piece of 1/2" MDF. I then took this to the bandsaw and cut out my shape. A small amount of touch-up work on a disc sander and I had my template. Rather, I should say I had my first template, because I was a bit too aggressive at the disc sander on one side and the result was not symmetrical. This was easy to verify by laying the template on another surface, drawing the outline in pencil, then flipping the template over and drawing it again. I could easily see where i had gotten a few flat spots, and I could also see that in general the curve on one side was a bit more pleasing. So I did it again, ripping the first template right down the middle (made safe and easy by using one of the bandsawn off-cuts to give me a straight edge) and using the "better" half for laying out both sides of a new template, this time from 1/4" plywood. Second time was a charm.

Now I had a template for drawing the curves on the actual form:

Next stop, the bandsaw. And…my next learning experience! To be continued.


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