JIANTAI Step Drill Bit Set 3-12mm 4-12mm 4-20mm 4-32mm Spiral Grooved for Faster Drilling Step Bits for Stainless Steel Metal Wood Plastic Unibit Cone Drill Bits

FunctionDeburring, Chamfering, Cutting or expanding holesSupporting tools: Pistol drill, Hand drill, Charging drill, Bench drill.4-32mm :(4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 24mm, 26mm, 28mm, 30mm, 32mm)4-20mm :(4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm)4-12mm :(4mm, 6mm, 8mm, 10mm, 12mm)Suitable MaterialWorkpieces with general hardness, such as wood, plastic, PVC plate, iron plate, plate thickness within 3MM. Please note that stainless steel and spring steel are not applicable. Not for quenching. (Water injection cooling while working, it can effectively extend the service life of the drill bit, especially in the case of continuous drilling)AttentionBecause of the outer diameter of each step of the step drill is gradually expanded,then the corresponding cutting resistance and linear velocity will also be gradually increased.Owing to the step drill is completely dependent on the inclined edge that is only with 1mm length,If the feed speed is too fast when drilling,it will be easily to be annealing caused by abrasion of the oblique edge.Please give a downward force when drilling, do not press down too hard to avoid the edge wearing.Package Includes1 x Drill Bit 4-12mm1 x Drill Bit 4-20mm1 x Drill Bit 4-32mm1 x Bag