Setting up the saw
Before using the saw to cut large heavy workpieces (like an assembled cabinet), I apply wax to the table saw fence and table to minimize friction.
I set the saw blade to 35 degrees and raise it to its maximum height. I make a lot of practice pushes through the saw (blade fully retracted) to make sure the jig clears the fence, and there is no opportunity for anything to get caught up or pushed out of alignment. No part of the cabinet should touch the fence, only the jig touches the fence. I also carefully arrange my outfeed and infeed rollers to support the cabinet as it goes into, and comes out of, the saw.
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Cutting the tapered bevels
I attached the jig to the back of the speaker. The left hand bevel is cut by placing the left side of the cabinet against the table, baffle facing the blade. The cabinet is fed into the blade bottom first. This means the blade starts by cutting the thinnest section of wood, but finishes by cutting the thickest.
When cutting the right hand bevel, the jig must be attached to the opposite side of the cabinet, and the jig itself must be flipped over and the L brackets attached to the opposite side. The right side of the cabinet is against the table, and the cabinet is fed into the blade top first. This means the blade starts by cutting the thickest section, and finishes by cutting the thinnest section.
I do not attempt to cut the full bevel in a single pass. My saw is very “old school” and it has no CNC features or any sort of precision measurement system built in. I mark lines on the work piece, and then I cut to the line. In the case of a big complex cut such as this, I slowly “walk” myself up to the line by making a series of cuts. I start by cutting about ½ of the cut width, and then carefully examining the finished cut to be certain everything is lining up. If there is an alignment or setup problem, I usually will have plenty of remaining cabinet material to make adjustments and continue. I continue to progress with deeper cuts, about ¼ inch at a time (6 mm). The final cut should be less than the width of the blade, and this ensures the smoothest possible cut.
It is absolutely critical that the jig maintain contact with the fence during the entire operation. It takes some force to push the cabinet through the blade, and it is easy to accidently push things out of alignment. It is best to practice pushing the cabinet across the saw table before using the blade.
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Cutting the top bevel
The top bevel is easier than the tapered side bevels, although it looks more intimidating. The speaker is placed top down against the table surface, with the baffle facing the blade. No jig is used, and the back of the cabinet is against the fence, and the bevel cut is parallel to the baffle. Once again I recommend practicing the motion first, and then making a first cut that is only half depth. Then walking up to the final cut line.
Why cut the top bevel last? When cutting the right hand tapered bevel, the top of the speaker goes in first. If the top bevel has already been cut, it would be very difficult to see the mark lines and position the line up to the saw blade. So I do the bevels first.
My final resulting cuts are close to the mark line, but not exact. This process is very sensitive to the angle of the jig, and how closely it matches the design angle. However, it is not so important that the actual cuts match the intended design, only that all four cuts are the same, and in this case I was successful.
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