butchering a polygon... what am I doing wrong?

 Forum topic by jamsomito posted 03-03-2021 07:01 PM 523 views 0 times favorited 10 replies
 jamsomito655 posts in 1478 days 03-03-2021 07:01 PM I’ve created a MONSTER! I took the challenge upon myself to make some coasters, but as a regular 20-gon (icosagon, 20 equal sides) because my Incra Miter 1000HD was taunting me with it’s quick reference guide: Turns out it’s not so easy. I resawed and planed some stock to thickness and cut perfect squares to start. I made a bunch of hexagons to get warmed up – no big whoop. But then I tried the 20-sided polygon and I found my brain is missing the cells it needs to make this work. I have no idea what I’m doing wrong. I learned the quick-reference chart was indicating half-angles for if you’re making a frame or something, so I’m actually using 18-degrees for my 20-gon. I even printed a template, cut it out, and used it to set up up my miter bar, stop, and blade. I just started cutting and it came out weird (actually 10 faces, but not equal length), so I tried again except this time I actually numbered the faces as I cut and got a worse result. Some strategies I’ve tried:1. reference each of the 4-sides of the square, make associated cuts at 18 degrees. Reference new faces, do all 4 again, etc. Repeat 5 times and I should have a 20-gon. Nope.2. reference one face of the square, make a cut, reference the newly cut face, repeat until 20 sides. Nope.3. reference one face of the square, FLIP THE PIECE and reference the same face again, repeat for all 4 sides. Nope. I’m completely baffled. I think it has something to do with my pointy-edges from starting with a square interfering with my stop. What’s the technique here? Do I have to move my stop for every round of cuts? Surely there’s a more mathematically proper way to do this to ensure 20 equal faces. I could just paste on the template and do it at my edge sander, but I want to try to get this right on the table saw. Any thoughts?