Wow, shit is lookin crazy. Lol at the bits cracking, what kind did you buy? The one I've got is only a 1/4" shank instead of the 1/2 and I can go thru a whole 3/4" MDF in one swipe. I'm guessing the birch is a little harder on the bits maybe.
I had 2 of the bits, so it wasnt a huge deal, one was a backup.
I made 5 passes total for each ring, the one that broke was 1/2way through the first pass. I guess just a shitty bit. The 2nd bit cut out all 4 holes, 1.5in birch without problems, so who knows.
Badass dude. I live about 30 miles from Jacksonville. I gotta see this when your done. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif