I am a trained carpenter. I bought this bit set to make some small doors. The first thing I did was set up one of the router bits on the router table to check for the gaps. Then I turned on the router and immediately noticed a constantly changing engine pitch (speed slowly changing). I looked down and noticed the bit was slightly wobbly and moving in the collet (yes I tightened it). I immediately turned off the router and grabbed the bits to return to Revain. These bits have a very large cutting head compared to their 1/4" shank. The slightest imbalance can quickly increase momentum and cause the bit to loosen. I was lucky to have avoided a potentially EXTREMELY dangerous situation If the bit had come loose from the collet or I hadn't noticed and actually tried to cut wood with the bit, I could have seriously injured myself.Not recommended.