<p>The numbers shown represent the maximum recommended drill bit diameter for the material shown.</p>

<p>Max diameter "masonry" drill bit is 32 millimetre</p>

<p>Max diameter "wood" drill bit is 42 millimetre</p>

<p>Max diameter "steel" drill bit is 13 millimetre</p>

CC BY-SA 3.0
2016-09-01T11:24:56.143Z
2016-09-01T12:35:04.770Z
2016-09-01T12:35:04.770Z
John Vukelic
<p>Thats the maximum bit <em>diameter</em>.  There are a couple of limits that are relevant: the outside of a large drill bit moves fast, so you may have to slow the drill down, but then it becomes less powerful and could stall. An optimised drill bit is assumed (e.g. using an HSS bit in wood is fine for many tasks, but at the large end it won't work). In practice you can often go a little bigger than they say with <a href="https://commons.wikimedia.org/wiki/File:Spade_bits.JPG" rel="nofollow noreferrer">flat wood bits</a>:</p>

<p><a href="https://i.sstatic.net/wYXAi.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/wYXAi.jpg" alt="Flat wood bits (via wikimedia commons)"></a> </p>

<p>or hole saws if you're gentle.</p>

<p>For many applications it's possible to have a drill with a shank that's smaller than the cutting end, hence the chuck size is less of a limitation. For example <em>step drills</em> are used for drilling sheet material:</p>

<p><a href="https://i.sstatic.net/XnnjK.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/XnnjK.jpg" alt="Step drill"></a>
This one has a shank of about 10mm and a maximum hole size of 26mm, mainly for metals.</p>

<p><em>Reduced shank drills</em> (or blacksmith drills) are used for deeper holes, again mainly in metals. These are a 16mm and a 25mm, with 13mm shanks:<a href="https://i.sstatic.net/OQ11S.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/OQ11S.jpg" alt="blacksmith drills"></a></p>

CC BY-SA 3.0
2016-09-01T15:21:07.217Z
The pictured bits are more than a little misleading since spade bits are intended for wood (or other relatively soft materials) and will quickly dull and wear down in brick or steel regardless of the diameter.
Ast Pace
CC BY-SA 3.0
2016-09-01T15:25:00.003Z
@AstPace when I put the picture in I was trying to find examples of blacksmith drills as well to illustrate the next point -- but couldn't find any with the right permissions. The image is captioned (and has alt text) "flat *wood* bits" so it shouldn't mislead anyone
Chris H
CC BY-SA 3.0
2016-09-01T15:58:34.737Z
On other Stacks (e.g. woodworking) a simple credit or link to the source is considered sufficient to display an image.  So you can certainly slip the image that you have linked into your answer.
Ast Pace
CC BY-SA 3.0
2016-09-01T16:53:32.953Z
@AstPace, I'd rather take a picture myself, but might not have the time. I don't think there's currently a consensus across the network and I come down on the side of only embedding libre resources.
Chris H
CC BY-SA 3.0
2016-09-01T08:13:26.753Z
2016-09-03T18:32:19.080Z
2016-09-03T18:32:19.080Z
Chris H
<p>I was looking forward to buying a drill for my crafts when I found this under the drill's photo:</p>

<p><a href="https://i.sstatic.net/U6fGN.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/U6fGN.png" alt="specifications"></a></p>

<p>I was wondering what do the metrics under the brick, wood and steel refer to? At first, I thought it was the maximum depth I can drill in these materials, but then I thought that this depended on the drill size and that it couldn't differ among different materials, so what are those numbers really for?</p>

CC BY-SA 3.0
2016-09-01T12:00:44.723Z
Can you link us to the drill page where you found this as well?
Matt
<tool-selection>
What do those material measurement metrics for a drill represent?
fady
# What do those material measurement metrics for a drill represent?

(Asked by: username_0 on 2016-09-01)

I was looking forward to buying a drill for my crafts when I found this under the drill's photo:

[![specifications](https://i.sstatic.net/U6fGN.png)](https://i.sstatic.net/U6fGN.png)

I was wondering what do the metrics under the brick, wood and steel refer to? At first, I thought it was the maximum depth I can drill in these materials, but then I thought that this depended on the drill size and that it couldn't differ among different materials, so what are those numbers really for?

**Tags:** tool-selection

> **Comments:**
> **username_1**: Can you link us to the drill page where you found this as well?  

---

## 2 answers

### Answer by username_2 on 2016-09-01. Score: 3

The numbers shown represent the maximum recommended drill bit diameter for the material shown.

Max diameter "masonry" drill bit is 32 millimetre

Max diameter "wood" drill bit is 42 millimetre

Max diameter "steel" drill bit is 13 millimetre


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### Answer by username_3 on 2016-09-01. Score: 3

Thats the maximum bit *diameter*. There are a couple of limits that are relevant: the outside of a large drill bit moves fast, so you may have to slow the drill down, but then it becomes less powerful and could stall. An optimised drill bit is assumed (e.g. using an HSS bit in wood is fine for many tasks, but at the large end it won't work). In practice you can often go a little bigger than they say with [flat wood bits](https://commons.wikimedia.org/wiki/File:Spade_bits.JPG):

[![Flat wood bits (via wikimedia commons)](https://i.sstatic.net/wYXAi.jpg)](https://i.sstatic.net/wYXAi.jpg)

or hole saws if you're gentle.

For many applications it's possible to have a drill with a shank that's smaller than the cutting end, hence the chuck size is less of a limitation. For example *step drills* are used for drilling sheet material:

[![Step drill](https://i.sstatic.net/XnnjK.jpg)](https://i.sstatic.net/XnnjK.jpg)
This one has a shank of about 10mm and a maximum hole size of 26mm, mainly for metals.

*Reduced shank drills* (or blacksmith drills) are used for deeper holes, again mainly in metals. These are a 16mm and a 25mm, with 13mm shanks:[![blacksmith drills](https://i.sstatic.net/OQ11S.jpg)](https://i.sstatic.net/OQ11S.jpg)

> **Comments:**
> **username_4**: The pictured bits are more than a little misleading since spade bits are intended for wood (or other relatively soft materials) and will quickly dull and wear down in brick or steel regardless of the diameter.  
> **username_3**: @AstPace when I put the picture in I was trying to find examples of blacksmith drills as well to illustrate the next point -- but couldn't find any with the right permissions. The image is captioned (and has alt text) "flat *wood* bits" so it shouldn't mislead anyone  
> **username_4**: On other Stacks (e.g. woodworking) a simple credit or link to the source is considered sufficient to display an image.  So you can certainly slip the image that you have linked into your answer.  
> **username_3**: @AstPace, I'd rather take a picture myself, but might not have the time. I don't think there's currently a consensus across the network and I come down on the side of only embedding libre resources.  

---

