Tactile Measuring Tool

My research into design pedagogies took me into the world of blind woodworking. There are blind woodworkers across the world, quietly going about their practice with the ease and adeptness of experts. Three blind woodworkers who have brought the joy of learning to me and other woodworkers are George Wurtzel, Jeff Thompson, and Clay Gurganus. You can also check out ww4b.org.

In general, blind woodworkers use the standard kit of tools without any modifications. One unique tool is the click rule, a tactile ruler similar to a depth gauge. A click rule is ubiquitous in the woodshop.

Image of the standard click rule. A rod with tactile graduations which extends from a tube

When I tried to use a click rule I was frustrated by a few things. For one, it required two hands to operate. I missed having a hand free to steady the workpiece being measured. Second, it sometimes needs to be locked into place by means of a screw, which adds a step of work, and again, requires two hands. Third, the measurement cannot be read as the tool is being extended, once again, because no hand is free for “reading.”

So I designed and prototyped a “one handed click rule” in my workshop. The prototype was exhibited in the Ada Slaight Gallery at OCAD University. About 100 people came by, but only 2 were visually impaired, and neither was a woodworker. They did express some interest, but, I do not think this tool will be replacing what exists.

The video above explains its operation, but in the simplest terms, a measuring rod is extended from a tube my means of rotating a gear with the thumb. Each “click” of the thumb is one-sixteenth of an inch. The rod has raised bumps every half inch, and by counting them with the clicks of the gear, a measurement can be taken. The gear “click” is created by a spring loaded ball bearing pressing into a detent.

Close-up image showing the hand cut gear and threaded rod mechanism. Because the rod is 16-teeth per inch, each click of the wheel advances the measuring rod a known distance of one-sixteenth of an inch.


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