A quick safety notice! I had a 1/8" endmill (1/4" shank) break during a run. When it broke it flew off and hit the back window of my car and shattered it! The bit could have just as easily hit me - so this had me search for the cause and how I could prevent it in the future. The cause was due to a number of issues the main being that a small cutout came loose and got stuck on the bit and when the router plunged back into the workplace the bit was pinched between the extra piece of wood and the workplace and cause the breakage. Ways to help prevent this: (1) use sturdier tabs on cut out items (2) use tabs for the holes within cut outs if they are large (3) along with adding tabs be sure that the table surface is level otherwise the tabs on one end of the workplace may be much thinner than intended. Finally I decided to also add guards around the perimeter of the machine's work space. I used 1/4" to 1/2" MDF (I used the thickest pieces that would fit) and I made them as tall as I could but also allowed the gantry to clear them to prevent a possible collision. Boxing in the workspace also had a side benefit of containing the chips and debris and keeping the leadscrews on the main axis cleaner. Bottom line: be careful and respect the machine.