Every farmer or mechanic has a drawer stocked with dull or broken drill bits. The plan is that “someday” we’ll take time to sharpen them…probably the second Tuesday of next week.
Here are tips to avoid adding to that inventory of mangled drill bits:
Drill bits come in a variety of base metals, from economy-grade High Speed Steel (HSS) to more durable molybdenum alloy bits, up through premium-grade cobalt alloy bits. Long story short, HSS bits should be considered disposable bits best used for wood, plastic and soft metals. Moly drill bits work well with mild steel. Cobalt bits are expensive and best choice for the abuse common in farm shops, but…drill bits by definition are “consumable items.” The differences between HSS and cobalt drill bits are price and lifespan.
Don’t be confused by “titanium” or “black oxide” drill bits. Those materials are coatings ap-plied to HSS, moly or cobalt drill bits to reduce friction and improve chip ejection. Once those coatings wear off a bit’s outer surface, you’re left with the base metal of that bit. Coatings are advantages, but not permanent solutions to drilling problems.
Drill stainless steel with care. Once a hole is started in stainless steel, don’t stop or reduce pressure until the hole is finished. No matter what type of drill bit is used, drilling stainless steel builds intense heat quickly. If the drilling process is interrupted, the intense heat “soaks” the bottom of the hole, hardens the steel and makes it even harder to drill.
Lube, lube, and then lube some more. Cutting oil is preferred, but WD-40 or other lubricants are better than drilling dry. Lubes cool drill bits, and heat is the enemy of any drill bit.
