How to pre-drill holes on your project wood pieces

This week our Jill of all Trades, Jill Washburn, gives us a quick tutorial on how to pre-drill holes when screwing together wood pieces for a project.

Pre-drilling, says Jill, keeps wood pieces from splitting during construction, especially if the wood is thin or fragile or you're working close to the ends or edges. But... there's a right way and a wrong way to do it.  

Jill says the key is sizing the hole properly. A hole that is too small or narrow, is not going to help much. It is still likely that the wood will split. 

A hole that is too large or wide, will keep the wood from splitting, but will likely make your construction weak, since there won't be enough wood left for the screw to bite into.

So, how do you know how to size the hole? Jill says it's not that difficult.  

She recommends using the screws you've chosen as your guide. Take the screw and examine the shank of it, meaning you're looking at the size of the center part of the screw, the solid part inside the spirals. Try to match the width of your drill bit to the width of that shank. You can go just a hair narrower, says Jill, but certainly, no larger than the width of the shank.  

Most people hold the drill bit over a sample screw to see how they line up.  

If you think that you're close but you're not certain, hold the drill bit behind the screw. If you can't see the drill bit, you're good to go. If you can see the sides of the drill bit when you are holding it directly behind the screw, Jill says you'll need to size the bit down just a tiny bit.

While it takes a minute or two to figure out the sizing, Jill says that the time invested is well worth it, since it saves lots of headaches down the road and makes for stronger construction on your project.  Plus, it will ultimately make assembling your project go faster.


To watch Jill show you how to size a drill bit for pre-drilling, just click on the video player above.