Six doors is a lot of money down the drain. Dave learned the hard way that the cheap bit is never really cheap. @singh.blair is right about the $30 fix but it goes deeper than that. A dull bit doesn't just ruin the cut, it heats up the wood and burns the edges so you end up sanding way more than you should. I watched a guy at the shop in Dayton wreck a whole batch of cabinet fronts because he kept pushing a spent bit instead of stopping. The bit tells you when it's done, you just have to listen to the sound and watch the chips. Spend the money once and your doors come out clean every time.