Symptoms
- Bit spins on the surface without cutting
- Bit gets hot quickly and loses its edge
- Smoke or a burnt smell while drilling metal
- Bit makes noise but very slow progress
Likely causes
- CommonWrong bit type (wood or masonry bit instead of metal-rated)Metal requires bits designed and hardened for it, such as cobalt or titanium-coated bits.
- CommonDrilling too fast for the metal type and bit sizeHigh speed on metal generates excess heat and dulls the bit quickly instead of cutting cleanly.
- CommonNo cutting fluid or lubricant usedLubricant reduces friction and heat, which is especially important on harder metals.
- PossibleDull bit tipA bit that's already been overheated once can lose its temper and stop cutting effectively.
- PossibleNot enough steady pressure to let the bit biteMetal needs firm, consistent pressure rather than light, hesitant contact.
What to do
- Confirm you're using a bit rated for metal (cobalt or titanium-coated twist bits, not wood or general-purpose bits).
- Slow the drill speed down significantly; metal drilling generally needs much lower RPM than wood.
- Apply a few drops of cutting oil (or a household oil in a pinch) to the drill point before and during drilling.
- Use a center punch to create a starting dimple so the bit doesn't wander.
- Apply firm, steady pressure and let the bit cut rather than forcing it or riding on top of the surface.
- If the bit overheats and turns blue, replace it, since overheated bits lose their hardness permanently.
Tools and parts
- Center punch
- Cutting oil
Cobalt drill bit set for metalSearch: “cobalt drill bit set for metal”
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.