Occasionally, when working in the wood shop, there are woodworking tasks that are a bit out of the norm, tasks that are a bit tricky to properly and safely complete. In these cases, the best way to handle the task may be with a custom woodworking jig.
What kinds of tasks?
Case in point: I was recently asked to design and build a custom piece of equipment that would require legs with compound angles (which I could cut on my compound miter saw). However, there also needed to be a lip cut out of the top of the legs to help support the top rail. As such, this lip needed to match the compound angles.
After a lot of thought, I considered two options for cutting this lip (short of cutting it by hand, which in this particular case, would've been a little too imprecise). My two options were to either set up my radial-arm saw with a stacked dado set and then adjust the radial-arm to make a compound cut. After the first cut, I could slide the board to the right on the fence a little bit, drop the blade a little deeper until the high edge of the angle cut matched the low angle of the cut I just made and make a second cut. I would then continue adjusting and making cuts until the lip was cut.
To my way of thinking, this wasn't really the best option. One little mis-judgment in the depth of the cut and my leg would be ruined. Additionally, there would need to be a lot of sanding to smooth out the successive cuts made by the stacked dado set.
The other option was to build a custom table saw jig, which is shown in the image above. The 2x8 that is standing up on the right side of the image is the piece being cut. The jig would work much like a tenoning jig, except that it would be built to accommodate the compound angle of the workpiece (that a tenoning jig couldn't handle).
To make the jig, I started by ripping a guide piece to fit into the miter slot of the table saw. This piece needed to be just cut so that when it was placed into the slot, it would be flush with the table top and slide freely (but not sloppily) through the slot.
Next, using a about an 18" long scrap piece of 1x6 (3/4" plywood would have worked well too), I attached the miter strip perpendicular to the long axis of the board with some short screws. Then, I ran the jig through the table saw blade to give the jig a true edge that would be parallel to the miter slot.
Finally, I marked the distance in from this true edge that denoted the line where the workpiece would need to be held for the lip to be cut. At this point, I cut and attached a 2x4 (cut with the needed 14-degree angle) perpendicular to that line.
My custom jig was now complete. All I needed to do was to attach the workpiece to the jig with a couple of short screws (that would be clear of the saw blade). I set the 2" depth of cut for the "cheek cut" (adding in 3/4" for the thickness of the jig) and completed the cut, making certain that I held the board tightly against the angled 2x4. For safety, because my right hand was supporting the 4' tall 2x8 workpiece, after the jig was safely past the blade, I turned off the saw and waited for the blade to stop before lifting the board and jig off of the table.
To complete the lip, I merely needed to remove the workpiece from the jig, set the angle on my table saw to 14-degrees, set my miter gauge to the proper angle and lower the saw blade to the appropriate height. A quick pass through the blade removed the piece that I started to cut with the jig, leaving me with a perfectly-notched lip in the leg, a task that would've been unsafe, imprecise or just plain difficult any other way.
Making these types of custom jigs really isn't difficult. It just takes a little imagination and some "outside of the box" thinking. Keep safety in the forefront of your mind and make sure that your jig is solidly built before you proceed. You may be surprised with the quality results.