Zero drop with a jig

I have seen many running shoes that have been modified, zero dropped, to make the heel and forefoot the same distance from the ground. These modifications were usually done by a cobbler or, sometimes, by the runner themselves using a knife. I wanted to try this on an old pair of New Balance 991. But, I wanted to try it using a jig on my bandsaw. I did not really need this pair of shoes modified. I just wanted to experiment and see what was possible. Is it possible to zero drop a pair of shoes using a jig on a bandsaw? Yes. I think so. Was my attempt a success? No. The short version: The jig worked well; I, on the other hand, did not. Let me explain.

The first item needed is the jig itself. There is a similar jig used on a tablesaw for cutting a taper. Coincidentally, it is called a taper jig. It is hinged at one end, can be locked at a fixed angle, and allows for cutting a tapered wedge from one side of a piece of wood while the other side of the jig is pushed along against the fence, which sets the distance from the blade. I surmised something similar could be used to cut the tapered wedge from a shoe using a much smaller version of the taper jig reversed and pushed along the fence of a bandsaw. The bandsaw has a much thinner blade than a tablesaw, which should allow the front of the wedge to meet at a point instead of step as with a thicker tablesaw blade.

This is the resulting jig. These pictures show the jig reversed from later operation.

It is of simple construction and consists of two pieces of 2×4 lumber twelve inches in length, a small hinge, a small wooden catch at the end of one 2×4 opposite the hinge, two cam clamps, and a cleared out piece of punched steel. The cam clamps and steel can be reversed to allow the jig to work either with the hinge toward the blade or away from the blade. In my test, I used it with the hinge toward the blade.

This is the hinge end of the jig. The slight gap from the hinge also allows for a slight negative angle if ever needed.

This is the business end of the jig showing the backer board stop, both cam clamps, and the steel strap to connect the sides. The 2×4 makes the jig tall enough that the steel strap will clear the fence on the bandsaw.

To cut a wedge from pair of shoes, some consistency is needed from one shoe to the other. This jig was to provide that consistency. It was stable and locked well into the set position. But, more was needed. The sides of shoes are not ideal for pushing along the table of the bandsaw. They are not exactly flat and even. To counter this, I used some double stick tape to adhere the sole of the shoe to a small rectangular board. The edge of the board would ride along the jig and bandsaw table.

This is the materials for that setup, shoes, consistently sized backer boards, and double stick tape.

This is one of the soles with tape attached at the front end of the where the backer board will go. I marked this position on both soles so it would be consistent.

This is both shoes with backer boards attached. The shadow demonstrates the height the side of the shoe will be above the table when cutting.

At this point, I am ready to cut the wedge. I reversed the jig from the above pictures, put one of the shoes against the jig, and began cutting.

Here is an action shot to show how it operates. I started with the cut near the upper first. This will let the material for the second cut be near the backer board and thus more stable.

I made the cuts on both shoes. It seemed to go okay. I had to press the toe a little to get the front edge of the cut along the sole.
At first glance, I have a nicely cut wedge in the sole. But, all is not as it seems.

The bottom tells the other side of the story. Unlike the top, it had cut well into the upper of shoe. Obviously, something had gone awry.

With a little bit more checking, I found the culprit. The shoe sole is quite rounded.

The rounded shoe sole is something I had not noticed and thus did not account for. The rocking of the rounded sole against the backer board, even with the double stick tape, led to inconsistency between one side of the sole and the other when cutting. This is part of the problem with trying to fit a new task into a short amount of time. I rushed it and did not pay enough attention.

Given what I now know the problem to have been, it probably could have been avoided. Taking my time and paying more attention would have helped a great deal. Two rows of tape on the sole would have helped. Using some barge cement and clamping the sole flat while it dried would have worked even better. A layer of paper glued between the sole and the backer board would have allowed for fairly easy removal. Now that I know to do it, I would have also aligned the the blade with sole edge nearer the table. With the side of the shoe lifted from the table by the backer board, there was sufficient room to see that side of the shoe. I could have also looked from the back side of the blade. That would have made it abundantly clear what was happening. Next time, I’ll know what else to pay attention to.

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