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Step 5Router Jig
The basic idea is to copy the shape from the original sandal to the wooden blank. The best solution is probably a computer-controlled milling machine - convert a file from AutoCAD and press go. Failing that, a manual milling machine. I believe one can be had for about $600, but the table looks too small. Of course, one can do it the old-fashioned way - by eye, with a mallet and set of chisels.
Originally, I had intended to make a pantograph , using an electric drill with a rotary rasp, that would allow free movement in three dimensions. But it seemed simpler to adapt a drill press, and make a jig to move the workpiece sideways. This allows movement in two dimensions. The 3D shape is built up in slices, like an analog TV picture. The blank and pattern are screwed to the jig from underneath. This leaves a couple of screw holes in the sandal, but they are covered by the rubber sole.
The drill press is actually an adapter to take an electric drill. It's not very good quality, and I had no qualms about drilling holes in it. I mounted a horizontal bar on the press traveller, and mounted a vertical probe in it, parallel to the drill bit.. When the drill lever is lowered, the probe moves in concert with the drill bit. The thing is not very rigid; you have to stop lowering when you see the probe touch the pattern, not when you feel resistance. The probe certainly won't act as a stop.
For horizontal movement, the wood blank and pattern (old sandal) are mounted on a wooden jig. The horizontal spacing of the blank and pattern matches the spacing of the drill bit and probe. There is a wooden rail clamped to the table to which the press is secured, and spacers fitted to hold the jig level. Thus it is possible to slide the jig horizontally in a straight line by holding it against the rail. The drill bit will trace a line across the blank, while the probe tracks the same path across the pattern.
To carve a parallel track, the rail is unclamped and moved towards the drill. The position of the probe is checked to make sure it traces the same line. The drill press allows the drill to be swung from side to side when a nut is loosened; with this setup, the probe rotates with the drill and moves horizontally. Given the geometry of the clamps and table, it is easier to swing the left end of the rail to move the drill across the workpiece (in reality, move the workpiece across the drill), and to swing the drill to move the probe across the pattern.
The drill is set up with a hemispherical router bit about 1cm diameter. When this is used as a router, sliding the workpiece while keeping the drill depth the same, it will carve a semi-cylindrical slot.
In practice, since the press is not particularly well-made and the jig has only limited constraints on uncontrolled movement, it is easier and safer to use the press as a press - drill a hole, raise the drill, slide the work sideways, then drill another hole
The video shows the steps of lining up the probe and router bit so that they track properly.
Originally, I had intended to make a pantograph , using an electric drill with a rotary rasp, that would allow free movement in three dimensions. But it seemed simpler to adapt a drill press, and make a jig to move the workpiece sideways. This allows movement in two dimensions. The 3D shape is built up in slices, like an analog TV picture. The blank and pattern are screwed to the jig from underneath. This leaves a couple of screw holes in the sandal, but they are covered by the rubber sole.
The drill press is actually an adapter to take an electric drill. It's not very good quality, and I had no qualms about drilling holes in it. I mounted a horizontal bar on the press traveller, and mounted a vertical probe in it, parallel to the drill bit.. When the drill lever is lowered, the probe moves in concert with the drill bit. The thing is not very rigid; you have to stop lowering when you see the probe touch the pattern, not when you feel resistance. The probe certainly won't act as a stop.
For horizontal movement, the wood blank and pattern (old sandal) are mounted on a wooden jig. The horizontal spacing of the blank and pattern matches the spacing of the drill bit and probe. There is a wooden rail clamped to the table to which the press is secured, and spacers fitted to hold the jig level. Thus it is possible to slide the jig horizontally in a straight line by holding it against the rail. The drill bit will trace a line across the blank, while the probe tracks the same path across the pattern.
To carve a parallel track, the rail is unclamped and moved towards the drill. The position of the probe is checked to make sure it traces the same line. The drill press allows the drill to be swung from side to side when a nut is loosened; with this setup, the probe rotates with the drill and moves horizontally. Given the geometry of the clamps and table, it is easier to swing the left end of the rail to move the drill across the workpiece (in reality, move the workpiece across the drill), and to swing the drill to move the probe across the pattern.
The drill is set up with a hemispherical router bit about 1cm diameter. When this is used as a router, sliding the workpiece while keeping the drill depth the same, it will carve a semi-cylindrical slot.
In practice, since the press is not particularly well-made and the jig has only limited constraints on uncontrolled movement, it is easier and safer to use the press as a press - drill a hole, raise the drill, slide the work sideways, then drill another hole
The video shows the steps of lining up the probe and router bit so that they track properly.
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Finally! something to do with that "portable drill press" (same as yours I'm sure)
I was about to toss it in the trash since it only works well if I bolt it to the piece I'm drilling.