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I like layout tools. Now, of course, a speed square and a lumber crayon are layout tools, but there’s no romance of craftsmanship there. It’s the fancy layout tools that catch my eye. Fine layout tools provide good results and inspiration. Moreover, I like to think (and hope) that by using well-made layout tools I’ll get a project off to the right start and will enjoy a well thought out and well-reasoned project. No uh-ohs, no panics, no problems.

So, I thought it was time to tackle a layout tool project in ShopNotes Magazine. My choice is a pair of dividers. Now, dividers don’t get used very often, but, when you’re dealing with layout work requiring the accurate division of circles, curved lines, scribing, or the transfer of dimensions from irregular objects they can be indispensible.

When I design a project, I find it’s often invaluable to build prototypes. Sketching and computer modeling are important aids in designing a tool. However, prototyping is when it all comes together. Learn by doing (learn by failing). When you hold and look at a tool in your hands and then use that tool, the faults and limitations quickly become apparent. As I work my way through designing these dividers, I thought I’d share my first prototype pair of dividers. There will be more, of course. Build, evaluate, change, and build again.

I started thinking about this design a few months back while taking a blacksmithing class. On the wall hung a large pair of hand-forged dividers. I thought they were beautiful. As I said, I believe tools should inspire us and there should be beauty in the objects that we surround ourselves with. So, I knew I’d have to make a pair. When I asked our instructor about the dividers, He said that they were patterned after a design by Leonardo DaVinci. DaVinci huh? I’d say that’s good source material.

These dividers are constructed of 5/32″ mild steel for the legs, 1/8″ steel for the wing, and some misc. parts. Metalwork, like woodworking, is often an exercise in reduction (to create individual parts) and then a process of synthesizing the individual parts to form the finished item. The legs and wing were laid out on blued steel stock and then cut out using a hacksaw followed by filing and drilling. I used a multidirectional hacksaw blade to cut the curved wing. One point of construction that I found interesting was riveting the two legs together. A brass rivet was inserted into the two legs, heated with a propane torch and hammered. Now the legs are supposed to move relative to each other, right? But aren’t they hammered tight? Well, yes. But we’re not done. If you heat the riveted area up with torch and begin to move the legs little by little, with some effort the legs will soon begin to move freely as the shank of the rivet is stretched and formed. Cool it all down in water and the metal will shrink and it will be freer yet. Certainly not a new technique but new to me.

The final design will be in ShopNotes 105. It may not look anything like what’s shown here. (I have a number of sketches to build prototypes of.) Build, evaluate, change, and build again.

Chris Fitch