Dull drill bits are a common problem that reduces drilling efficiency and precision.
But don’t toss those old bits just yet – sharpening drill bits is an effective way to bring them back to life and avoid the cost of replacing them.
Why Do Drill Bits Become Dull?
Even the highest quality drill bits will dull with repeated use as the sharp cutting edges gradually wear down.
Pushing bits too hard, drilling at excessive speeds, or inadequate lubrication accelerates this wear, especially with harder materials like stainless steel.
Drilling through abrasive materials like hardened steel, treated lumber or fiber cement board will abrade the cutting edges faster than soft materials.
Lack of lubrication allows damaging heat to build up, while improper storage leads to chipped edges. And cheap bits made from softer, less durable materials naturally can’t hold an edge as long.
Identifying Dull Drill Bits
You’ll know your drill bit needs sharpening when you see visible rounding over or chipping of the cutting lips. The tip may be discolored or blued from overheating.
A dull bit requires more force to cut and tends to wander rather than drilling accurately. You may notice smoke or a burning smell from the excessive friction.
Other telltale signs include slower drilling progress, rougher hole edges, and a screaming or chattering noise that indicates the bit is struggling to cut.
If you see small chips or dust rather than long curled shavings, it’s time to sharpen up.
Methods for Sharpening Drill Bits
You have several options for sharpening your dull bits depending on your available tools and the amount of material that needs to be removed:
- Bench Grinder – The fastest method uses a high-speed bench grinder to quickly restore the cutting edges. While it risks overheating the bit, a grinder is ideal for badly damaged or neglected bits.
- Belt Sander – A vertical belt sander offers more control with less aggressive material removal. It’s a great choice for minor touch-ups, though holding the correct angle by hand takes practice.
- Drill Bit Sharpening Jig – For the ultimate precision, a sharpening jig clamps your bit at the perfect angle for consistent results every time. Use it with a grinder, sander or even by hand.
- Dremel or Rotary Tool – A handheld rotary tool with a diamond burr works well for sharpening small bits or quick touch ups. The high speed and light touch allows you to carefully sculpt a fine cutting edge.
- Sharpening Stones – Oil stones or diamond hones are an inexpensive manual option for frequent maintenance. Though slower than powered methods, a few careful strokes are all it takes to keep your bits in top shape.
Steps for Properly Sharpening a Drill Bit
Whichever sharpening method you choose, follow these steps for the best results:
- Start by cleaning your bit to remove any debris or grease that could clog the abrasive.
- Use a vise or jig to secure the bit at the correct angle, typically between 118° to 135°. (ref)
- Identify the cutting edges and maintain that angle as you grind each cutting lip evenly.
- Check frequently with a gauge to ensure a consistent angle and avoid overgrinding.
- Grind the heel behind the cutting edges for proper clearance.
- Lightly deburr the sharpened edges with a fine stone for a razor sharp edge.
- Check that both cutting lips are even and the point is centered.
- Dip frequently in water or oil to cool the bit and prevent heat damage.
- Polish the flutes and coat with bit wax or oil to prevent rust.
Tips for Longer Drill Bit Life
Proper drilling techniques and maintenance will keep your newly sharpened bits in top condition longer:
- Match the drill bit to the material, using harder bits for tougher jobs
- Always apply cutting fluid to lubricate and cool the bit
- Maintain steady pressure and controlled feed rate
- Drill straight by hand or with a guide to prevent side loading the bit
- Touch up the edges regularly vs. waiting until the bit is fully dull
- Clean and oil bits after use and store safely to protect the edges
Why You Need to Sharpen Your Own Drill Bits
Sharpening your own drill bits is a valuable skill that can save you time and money. With a few basic tools and proper technique, you can keep your bits cutting cleanly and accurately hole after hole.
So the next time your bits get dull, try sharpening before you go shopping!
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Davin is a jack-of-all-trades but has professional training and experience in various home and garden subjects. He leans on other experts when needed and edits and fact-checks all articles.