I have a drawer of tons of drill bits from all over the place - many donated.

Almost all of these bits are dull black or gold-ish colored and don't have much else in the way distinguishing them (that I know to look for). They just look like generic drill bits (not forstner, paddle, etc).

Someone told me not long ago not to use metal drill bits on wood and vice versa. I've never heard this before.

How to identify a wood drill bit from a metal drill bit - and does it matter?

  • Me too, Ive been using metal bits always, for Decades! No one told me at the Hardware store ! – Philip Oct 1 '17 at 22:21
  • I used a metal drill bit to drill holes in my kitchen wood cabinets for handles.... Every hole was off... I'm glad I read this so I know why as I was using a template to make sure the holes were the correct width apart; now I know why they moved around! – Deb Jan 3 at 20:22
up vote 24 down vote accepted

It does matter - wood drill bits won't work on metal (destroying the bit in the process, unless used on thin and soft metals) and metal drill bits will increase splintering and tear-out when used on wood (but this depends also on the wood type and the diameter of the bit, and for smaller diameters there is little difference between wood and metal drills bits).

As for how to tell them apart - wood drill bits have two distinguishing features: a spar (also brad) and a lip. The spar helps in keeping the bit centered when starting the hole and prevents wandering of the bit on the surface of the wood. The lip acts like a chisel, slicing through the wood fibers in the circumference of the drilled hole, improving the quality of the finish. This is most important for through holes, where the lips helps reduce "blow-out" of the wood when exiting the wood on the other side. Wood bits are typical black and silvery in color, but other colors exist.

Wood drill bit

Metal drill bits, on the other hand, have just an angle at the tip. They often are fully black (plain HSS), golden (often titanium oxide finish) or coppery (often cobalt steel) in color:

Metal drill bit

 

  • 7
    I have basically been using metal drill bits for everything I do my entire life it seems. – NipFu Feb 25 '16 at 22:34
  • As I mentioned, metal drill bits work fine on wood, they just leave a worse finish on the hole. I would recommend using wood drill bits for wood, though. – Eli Iser Feb 26 '16 at 5:41
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    The picture of the bit above with the sharp point is known as a brad point bit. Many bits on the market are generally multipurpose, and can be used on a variety of different materials. The advantage of a brad point is that you can make the hole placement much more accurate in wood. The point will help prevent the bit from "walking" around. – Jason Hutchinson Mar 4 '16 at 21:34
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    +1 @JasonHutchinson Especially when one's drill press has decided to start walking around. I would also add that "metal" bits work fine for things like drilling sheetrock to hang a TV, or other tasks that your average Big Box drill bit purchaser is likely to have in mind. Just not for precision work. – 3Dave Aug 20 '17 at 2:58

There are also copper coloured metal drill bits that are more suitable for metals, then there are darker metal drill bits that you use for walls.

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    Can you provide links to some examples? I've seen wood bits of all different kinds of colors... – mmathis Oct 3 '17 at 14:42
  • The gold color is titanium nitride, very hard , very thin ; only an advantage when cutting metal. – blacksmith37 Jul 2 at 14:59

protected by Community Jul 3 at 14:20

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