My 3D printed zero clearance inserts for the miter saw have not held up well. They don’t react well to heat and I only get a few dozen cuts out of them before cut tears start to appear. The plate has to be 1/4″ thick which makes it difficult to design for. I have used plywood in the past, but that is tough to make work right. I finally broke down and picked up some phenolic sheet. Phenolic is paper impregnated with a hard resin. The result is really stiff and slick.
I started by copying the insert that came with the saw and expanding it a little so it fits tighter in the opening. I made a test piece and when everything turned out ok I wrote the instructions on the master. First cut a piece of phenolic to rough size, attach the master, and trim it down on the router.
Once the shape is cut right I peel the master off and stick down the original saw plate. I use it to transfer the hole locations with a 3/16″ transfer punch. Transfer punches come in handy for just this sort of thing. Next I do a counterbore to give the screw head some place to live, then finally drill through the rest of the way.
The new plate is screwed into place, then I just make the first cut and voila, the zero clearance insert is complete. My first one had seen dozens of cuts without any issues. Hard to say how long these will last, but as hard as the plastic seems, it should be quite a while.
I have gotten some good use out of my router radius templates. I saw an interchangeable jig system that did a similar job and included chamfers in addition to the radii. First a reminder of how they work. You sit the template on top of the wood and use a special router bit that is a cutter with a matched diameter bearing on top. The bearing follows the template and removes any wood that protrudes beyond it. Ideally you cut off as much waste as you can on the bandsaw or elsewhere. Routers don’t remove a lot of material well.
I modeled a variety of them from 0.5″ to 1.25″. The length given is a leg of the isosceles triangle that will get removed, not the hypotenuse. See the diagram below.
I printed a stack of them in case the need arises, and uploaded the design to thingiverse. If they look odd compared to my normal prints, it is because I used some cheap translucent filament I had lying around. I figure they will get torn up eventually, so no need to use the good stuff.
Two hobbies collide as I print something super nifty for my wood habits. A cool thing you can do with router tables is apply a template onto wood, and use a templating bit to match cut. The bit has a bearing of the same diameter as the cutting edges. It rides against your template and cuts away any underlying wood that isn’t shaped like your template. Super handy, but you need a good template to start with. Enter the 3D printer.
I modeled up this little jig so that it hooks onto the edges of a board and gives an exact radius. It is hard to see given the color, but I printed a 1″ text in the bottom to note the size of the radius.
Here is a picture of the jig fully seated, and what the resulting cut looks like. Very clean and smooth. The large circular cutout gives a lot of finger purchase so you can hold it tight and far away from the spinning bit.
One concern I had was with the material. Would the cutting friction heat up enough to melt the plastic. I did 4 cuts on a 3/4″ bit of plywood and everything looked good. If I had a hundred corners to do, I would worry. I could always upgrade to PETG.