MDF is really hard on tools Posted on May 14, 2016 by jablake53 My router bit started cutting really ragged. This is my 3rd bit. I’ve ordered 2 more and will get them Monday. A brand new 140 tooth circular saw blade only lasted for about 20 long cuts and it started warping and cutting wavy. Share this: Click to share on X (Opens in new window) X Click to share on Facebook (Opens in new window) Facebook Like Loading...