My plan to build a houndstooth cutting board led me to a conundrum. One of the square profiles in the design needed the corners cut off, so the resulting square profile was cut out of the original profile at a 45-degree angle. Normally, I’d tilt my table saw blade to cut a 45 and be done. In this case, the profile was small and I felt uneasy making the cut.
I had been bouncing this problem around in my head for some time. I mentally iterated to a design concept that would hold the corners of the square leaving the faces at a 45-degree angle. With the part held in this orientation, my saw blade could stay perpendicular to the bed, and my hands would be far from the blade.
Rather than blather on, let me show you how I built it.
Starting with three pieces of maple, I milled two of them to the exact same width. These will be the clamping members. For the piece to be perfectly angled, the clamps must be the same distance from the upright connecting member. Making this jig out of plywood might make it more stable, but I didn’t have any in my shop.
With a 90-degree grooving bit, I set my router fence to mill the grooves in the clamps. To be precise, I used the edge of the board that attaches to the uprights as my reference surface.
After milling the grooves, I added a relief at the apex of the groove on the table saw. This reduces the effect of sawdust or any inconsistencies when clamping the part.
I added some adjustable stops on the bottom plate thinking I might need a reference for the part on the last cut. The reference corners will be removed, so the grooves will no longer align the part. These aren’t fancy. Just enlarged and counterbored holes to create some adjustment. The blocks are attached to the bottom plate with threaded inserts.
Stop blocks installed on bottom plate. A reference part milled from a 2×4 is sitting in the groove.The next step is to attach the upper clamp to the upright. It will have a macro-adjustment for different profile sizes and a clamp to tighten the profile in the grooves.
Using a router, I milled counterbored grooves in the upright…
…then added inserts into the edge of the upper clamp. The large holes in the upper clamp are access holes to adjust the stop blocks once the jig is assembled.
Here are the three pieces almost ready for assembly. The last thing to add are the clamps.
I added a dado to the bottom of the lower plate to accommodate two T-Bolts. I then drilled holes through the upper and lower plates for the T-Bolts.
With all the holes drilled, I attached the lower plate to the upright with screws. My plan was to glue it and screw it, but I wanted to be able to take it apart in case it needed modifications. Good thing I did. After using the jig for the first time, I found I needed to elongate the slots on the upright. The upper clamp would not drop down low enough to clamp the part securely after I cut off the first corner.
I ran a couple of test cuts on softwood.
The intended use of the jig:
The upper plate is adjusted to the correct height. The square profile is clamped in the grooves by the corners by tightening the clamping knobs and the first cut is made. The part is then unclamped, slid out of the jig, and rotated 90-degrees. The upper clamp plate is lowered to capture the shorter part, and the clamping knobs tightened, and the second cut is made. The part is rotated, The stop blocks are moved against the flat surface of the part and tightened, and the third cut is made. Finally, the part is rotated another 90-degrees and the upper plate is lowered to the height of the part. The part is then bumped up against the stop blocks, clamped down, and the final cut is made.
The actual use of the jig:
The jig worked nearly flawlessly for the first two cuts. Unfortunately, I did not have the adjustment range built into the stop blocks to make the third and fourth cuts. I milled the third and fourth faces of the profiles down using my thickness planer. It was not optimal for efficiency, but it didn’t affect the accuracy of the part nor the finished product. The first two cuts are the most important because they are used as the references for the third and fourth cuts.
The first modification to the jig will be making new stop blocks with slots for more adjustment range.
The second modification will be to add a fixed stop at the rear of the jig. I made twelve cuts when building the houndstooth board and one of the parts slipped rearward in the clamp about a half inch because the clamp was not tight enough. I’d rather not rely on clamping force to hold the part, but a positive stop.
Of course I had to add my logo and drill a hole along the center of gravity so it hangs straight on my slowly accumulating wall of shop-made tools.
