2-Wing Round Shank With Slow Spiral For Wood Screw, Includes High-Speed Steel (HSS) M2 DIN 338 Fully Ground Drill For use in handheld drill, drill press & CNC machine when used with CNC Spring Collet*. Carbide-tipped for long lasting results.Used to countersink and counterbore holes for the heads of screws in woods, plastic and non-ferrous materials. The 2-flute integral design ensures uniform and concentric results each and every time. Carbide tips provide chip free hole edges and last at least 40 times longer than steel countersinks. Available in a wide variety of sizes, complete with the HSS M2 fully ground drill bit.Excellent for Drilling:Natural WoodsMan-Made BoardsMDFChipboardPlywoodAluminum/Non-Ferrous*Aluminum Composite Materials (ACM)*Composite Decking Materials*WARNING!: For optimal results and extended tool life use lubricant or air cooling. Ensure the material is fixed and drill is stable while drilling. CNC Countersink Drilling countersinks with these bits on the CNC machine is a great way to save time and have your pieces look great every time!With the adjustable depth drill bit you can adjust them for whatever size material you're working with. They are best used with a drilling toolpath, utilizing the peck drill option at 0.25" per pass with a 0.125" retract height.For best results run at 3,000 RPM with a 30 Inches Per Minute (IPM) plunge rate. No feed rate needs to be set with these as they only move up and down with the Z axis, not side to side. If your software doesn't allow a 0 feed rate, you can enter 1 IPM in the feed rate as a placeholder.*For 5/16" dia. round shank use a 7-8mm Spring Collet. For 3/8" dia. round shank use 9-10mm Spring Collet.