Preamer Spiral Groove HSS Ladder Step Drill Bits Set for Metal Wood Hole Saw Drill Bit Set,10-45mm

• Unique ladder structure , it can open multiple Aperture
• it can not easily be broken.8 stepped:10,15,20,25,30,35,40,45MM
• It can deburr, chamfer and open hole, but ordinary twist drill can't
• The step drill bit is made from upgraded high speed steel characterized by well-balanced toughness, wear resistance and red hardness properties for better and faster hole -drilling performance. The coating makes the drill bit more durable so that it can last for years with uncompromised quality.
• Surface Treatment:nitrogen treatment (increasing the hardness and abrasion resist.Material: HSS 4241

Tool using: pistol drill, bench drill. Water to make ti cool while working, it can effectively extend the service life. Recommended drilling speed 250--400 rpm Suit for use in hardness under 25 artifacts(Such as iron, steel, PVC panels, wood board ,Do not fit for cutting Stainless steel) , The plate thickness under 5mm