The Warning Disc is colored with a pattern to increase awareness of spindle rotation. Use a Warning Disc^TM with a larger diameter than the cutter diameter. 

Using the Warning Disc above the cutter helps reduce cutter exposure from the top and also deflects chips. 

The Warning Disc is one part of a machine setup. Always use the proper guide devices (such as fences, guides, ball bearing rub collar, etc.), holding devices (such as jigs, hold downs, power feeders, etc.) and a dust shield in conjunction with the Warning Disc.