So I was a bit nervous about cutting the plywood. It seemed so thin and I was worried about tearout. So I made a zero clearance insert for the 20tpi DeWalt ply blade I got. It’s pretty easy to make. Unfortunately the only way to attach it to the base of my saw is via carpet tape.
![](https://maximfx.com/wp-content/uploads/2020/08/20200811_202617-498x1024.jpg)
luckily cutting with the Porter Cable jigsaw was easier than I remembered. Make sure you set the saw so the teeth go straight up and down.
Scarf joint jig
Even though the jemwatercraft plans call for butt or fiberglass taped joints I decided to try and go for scarf joints after reading about all 3 of them. This gives the best strength, weight and visual look. It doesn’t seem that much harder if a jig is used. I created one with this design for my router as people suggested it produced cleaner cuts than circular saws.
![](https://maximfx.com/wp-content/uploads/2020/08/20200811_201036-1024x498.jpg)
Of note, there are side rails holding my router guide in place to the slope rails. I went with this design vs the others where the router is fixed to a base that you slide back and forth because I was afraid my base would become non perpendicular with the slopped rails making the cut off a bit.
With this design the base will always be perpind6 giving the correct angle. My Rigid router slides Cross the top of the base with a guide to help it.
I tested it out on some scrap and it worked pretty well the only problems are the bit has to be extended a bit to reach the workimg surface. Also it can be a bit hard to slide the router back and forth on the mdf. So if your making one maybe melamine for the base and the rails a bit lower.
One nice plus is you can clamp the base to the slopped rails if you wanna take it slow and safe.