I'm new to woodworking so hopefully this question falls within this exchanges guidelines, please advise if not.

I'm trying to drill the screw below into plywood as shown in the photo: enter image description here

There will be a block of wood in the slot in the above photo that I worry will split if I don't drill a pilot hole first. The only issue is that my drill bit is not long enough to make it all the way through. As shown below: enter image description here

So I realized that I need to buy a new drill bit but I am struggling even to do that. My drill (shown below) seems to only accept hex shaped drill bits which drastically limits my selection. enter image description here

These are the screws I'm trying to drill, they are 12 x 3 inches long, shown below: enter image description here

Why are the screws listed as size 12 but all drill bits are listed as fractions as shown here? How am I supposed to know what size is correct? And moreover, how can I tell if the length of the bits are at least 3 inches none of the packaging seems to list length, only the size as a fraction. :

enter image description here

To complicate matters, I want the screw to be perfectly flush so I believe I need a countersink to do that properly, I've been looking at the countersinks below I can't tell if the bits are at least 3 inches or whether the width is correct. enter image description here

I am totally overwhelmed at this point - which drill bit should I be using?

  • 1
    That's not a drill, that's an impact driver that people just happen to make drill bits for. Commented Oct 26, 2018 at 9:50
  • 1
    @ratchetfreak judging by the clutch settings, it's probably a drill driver and not an impact driver. DeWalt (and some other companies) makes hex chuck drill drivers, mostly in the 12V product range.
    – Eli Iser
    Commented Oct 26, 2018 at 12:19
  • Well-asked Question. Two previous Q&As you might like to read that will help in the future, Which type of drill bit for which jobs? and How can you make a regular screw into a self tapping screw?
    – Graphus
    Commented Oct 26, 2018 at 15:26
  • Here is some information about screw sizing: diy.stackexchange.com/questions/13824/… . Basically, they're measured in gauge instead of size because there's a lot of sizes close together, so just measuring the major diameter would be error-prone. Commented Oct 26, 2018 at 16:05
  • It is definitely a drill not an impact driver. It doesn't make the same noise as impact drivers do. Just a weird drill
    – Matt
    Commented Oct 26, 2018 at 16:13

1 Answer 1


The tapered bits are the proper bit for that process. You can by (and most do) with just using a properly sized standard drill bit.

Here is a chart for screw size vs bit size based on the type of wood you are drilling into: Wood Screw Pilot Hole Sizes

The standard bits are more useful overall, so if you don't want to spend the money now on the tapered bits, just get the first set you linked and use those.

Regarding your drill. You will almost certainly want to invest in a drill with a standard chuck at some point. A standard three jaw chuck supports more bit sizes, and will have less runout (wobble in the bit that causes the hole to enlarge).

  • Do you know if the tapered bits are long enough? I can't see anywhere that indicates whether the one I need (I believe the #10) is at least 3 inches
    – Matt
    Commented Oct 26, 2018 at 16:12
  • They are probably long enough to do the job. You are not as likely to split the wood once you are in a ways. Alternatively, you could use some better screws (SPAX or GRK) that have a limited self-drilling tip.
    – LeeG
    Commented Oct 26, 2018 at 16:24
  • 1
    I just got home and measured my set. It looks like if you remove the counter sink head, you could drill up to 2 1/4" with the #10 taper bit.
    – LeeG
    Commented Oct 26, 2018 at 22:12

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