Precision Self-Centering Drill Bit Self-centering precision centering bits are essential for pilot holes in hinges, handles, drawer slides and other parts, the cone that surrounds the drill ensures that the pilot hole is centered relative when milling the fixing hole, drill a pilot hole Sharp 135 degree oblique edge of the bit head, make the hinge drill more quickly drilled in the position of the hinge holes. the guide that surrounds the drill bit is pushed by a spring to keep it in contact with the countersink the part to be repaired. Wood chips are automatically discharged Sawdust automatically drains from both sides of the holes, without a stuck drill, you do not need to remove wood chips, effectively increasing your work Easy to use and install Different hardness wood, need different centering drill, just disassemble the screw and replace the drill. Professional tutorials on using vedio will be provided. Product Size: 4pcs selfcentering Who is it designed for Mr. DIY - Professionals or amateurs as carpenters, mechanics, cabinet makers, furniture makers and other craftsmen working with wood. - These self-centering pre-punch tips are ideal for pre-drilling holes for fasteners, including hinges where it is essential to have a perfectly centered pre-hole. - The 4 points are of different sizes, to adapt to all models, from the largest to the smallest. Single value: 1. Provide professional vedio use tutorials, please contact us 2. Long-term durability: brass shell, high speed steel drill bit, appearance electroplating, 14 months warranty 3. Better perforation performance: positioning accuracy, will not move, the chips will automatically discharge from the hole on each side of the top of the drill, and will not cause problems with wood chip jamming Common size instructions: The 4 most common hinge screw sizes are 5/64 , 7/64 , 9/64 , 11/64 . 5/64 : The hole diameter is about 2mm, Use about 2.2 - 2.8mm sheet metal screws 7/64 : The hole diameter is about 2.8mm, Use about 3 - 3.5mm sheet metal screws 9/64 : The hole diameter is about 3.5mm, Use about 4 - 4.5mm sheet metal screws 11/64 : The hole diameter is about 4.5mm, Use about 5 - 5.5mm sheet metal screws Whats inside the package: 4pcs Hinge Drill Bit Note: Please adjust the adjustments according to the hardness of the wood when opening, if the wood is soft, you can choose a smaller size, if hardwood, choose matching or larger size.