Furnished content.
(from Lumberjocks.com)
This post is about making a jig to cut the inserts for the ZCI (Zero Clearance Insert) plate for the SawStop Job SIte saw.To make the insert with the miter gauge see this project.https://www.lumberjocks.com/projects/422166I used the mfg supplied insert that came with the red Aluminum Plate for the saw.Ideally a 12×12 piece of plywood would be the size to use. Mine is 11 X 9 but it works. I put a miter slot slider on the bottom of the Plywood. See my posting for how to make the Miter Slot Glide Bar.https://www.lumberjocks.com/projects/422136When mounting the bar to the jig surface use you miter gauge in the slot on the other side of the blade so that the Miter Slot Glide Bar is able to sit under the plywood This is why MFG put two miter slots on saw surfaces so that you can use them both at the same time. See picture above.I mounted the glide bar and the plywood in a position that when you cut the blade side of the jig that it is cut with a 60 degree angle. I set the angle by using a 30-60-90 degree triangle. A blade angle electronic device could also be used.
When those 2 pieces are attached then glue a strip of wood across the front of the jig. You are gluing it to the edge not on the top surface. The reason being that the front edge is a 90 edge from the blade. Once it's glued on then cut the edge with your 60 degree angle blade. This makes the front piece having a 60 degree cut so that you have it as a measurement that can be used as a reference when cutting the ZCI piece. I also glued a piece on the right hand side of the plywood jig. This is used as a part of the length measurement of the insert that you are making.See my picture of the right hand edge.
One more piece to glue on. This is apiece that is used to cut the width of the insert piece. In this case 3 1/2” from the blade. I hold the MFG insert to the blade that is sitting at the 60 degree angle and then glue on a block of wood that buts up against the mfg insert. Again look at the picture. That's picture 2 in the pictures above. Picture 3 is the cutting of the width of the insert.So you now have attached 3 pieces to the jig. 4 if you count the miter guide bar.The front one is 90 degrees to the saw blade the right hand one will be used to cut to the correct length of the insert. It should be 90 degrees to the front piece. The third one is to cut to the correct width and make the insert with 2 parallel cuts. 1 straight 90 degree and a second one at 60 degrees.You need to cut one additional piece of wood. it will be used to cut your insert to the correct length. Seen in picture 4.With the blade raised but turned off put your MFG insert touching the blade and measure to the right hand stop you glued on. Now cut a piece of wood about 1/32 to 1/16” smaller than the measurement you just found. The reason it's smaller is to that you can control that distance by the use of masking tape. Without any tape you will cut your insert too long, and as you add tape the insert will be getting shorter. My control piece is a 3/8” thick piece of wood with maybe 10 to 20 pieces of tape. I've got a storage area to hold extra tape if I need to add or take away some measurements I've found on my tape that 2 pieces were about 1/128 of a inch. Duct tape would be thicker if you need to fill up space. Or you can glue on a piece of wood and then retrim to the correct measurement. But the final adjustments should be tape pieces.To do the final adjustment I'll trim up some scrap pieces to see that I can get the length to the final size.Making the cuts to the rough cut over-size piece for the insert.Cutting order:First I cut to width, That gets the two edges on the insert parallel and 3 1/2” wide.Then I cut the first end to the bevel without using the length edge. Then I use the length block to cut to final length. Make sure that the long edge of the insert is up and not down. You also want to make sure that the first end cut has the insert oriented so that the bevel edge matches the bevel you cut on the side.One other tidbit of information that I tried to follow and in some cases, but in other failed. If you hold your insert in your hand before making any cuts if there is a slight or sever bow, you want it to be down once the edge cuts are made. That will make your insert fit tighter once installed in the plate. This means that the bow is up as you are making the cuts, because the up side is the long edge when being cut.Confusing I know, but it works.