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I built a cabinet from big-box plywood. I used 1/2" for tops and bottoms and 3/4" for the sides.

This 16"dx22"hx30"w deep cabinet will be inset into the wall and fastened to the studs (so the back 12.5" will be hanging with no support). It will then be trimmed and painted so if a joint ever fails, it will be a big problem.

I used 1 1/4" screws, with pre-drilling and countersinking. But, TBH, it didn't feel like there was enough grab. Did I use screws that were too short?

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Or did I pre-drill it with too big a bit?

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  • Just for clarity you might want to edit to say under-length, since undersize would, I think, commonly be understood to mean the screw gauge, not length. So anyway, if you glued as well as screwed (which is both common practice and very advisable) then you're probably fine, since the glue might do most of the heavy lifting. If you feel you need the extra security though by all means go with longer screws (with the appropriate pilot created as necessary). And it'll give you the opportunity to use actual wood screws instead of bugle-head drywall screws :-)
    – Graphus
    Commented Sep 30, 2023 at 6:39
  • Drywall screws actually get a lot of bad press in woodworking circles but actually they seem like they're fine in practice so don't sweat using them in future. Most of the bad stuff said about them is based on assumptions and repetition of other people's statements, not on any actual testing of drywall screws for wood/board materials. Stumpy Nubs did a video on this last year if you're interested in seeing more.
    – Graphus
    Commented Sep 30, 2023 at 6:42

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Did I use screws that were too short?

I'd personally be a little concerned they were a tad short, mainly if they were the sole means of fixing (but also in a different context1). As I mentioned in the Comments, if you glued as well as screwed then the glue will of course be doing a lot to hold this cabinet together, and in an ideal world could be used by itself with no brads, nails or screws to help lock everything together.

did I pre-drill it with too big a bit?

Sorta. But if the combination bit was adjusted exactly as seen in relation to the screw, no I don't think so. You certainly would not want to drill a full-length pilot hole with a bit of that size2 however!

Note: a proper combination bit for pre-drilling in a single operation should either have a longer, tapered bit in its centre, or be stepped, so that it drills two distinct holes sizes — for the clearance and pilot portions of the hole.

1 Given this is not a freestanding cabinet and will be built into the wall though, I think you have zero to worry about.

2 Remember there are two or three components to pre-drilled holes, the countersink/counterbore on top (IF present), the clearance hole that the screw should not engage with (assuming the threads extend up that far), and the pilot hole. The pilot hole should be approximately the core diameter of the screw used, no larger, and in softer wood and plywood (also MDF and chipboard) you can get away with under-drilling the pilot to maximise hold.

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Yes, you used the wrong screws and at the wrong angle. Sheetrock and or drywall screws are designed for there purpose. Which is NOT wood working screws. They are to brittle. Next time, do yourself a favor and get a pocket hole jig. They are self explanatory and very strong. This jig is designed to connect inside corners and hidden fasteners. They take the guesswork out of the equation. Like the gentleman before. You should be OK with your project. I am a professional finish carpenter with 30 years experience.

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  • 2
    Hi, welcome to StackExchange. I'm afraid I've also been guilty of spreading the myth or misconception about drywall screws being brittle. Perhaps some are (or they used to be?) but it's clear some aren't. Stumpy Nubs did a video on it last year if you want to see more, which includes his examples of them not failing after many years under heavy load :-)
    – Graphus
    Commented Nov 15, 2023 at 18:50
  • Long before the internet was available to spread myths at the speed of light, I built a storage rack out of 2x4s and held it together with 2" & 3" drywall screws. It stood for more than 25 years and was loaded with more and more cruft over the years. 99% of those screws were in shear and none failed. I don't use drywall screws for projects now because I've grown a great disdain for Phillips head drive and much prefer Torx (which is 100% inappropriate for dry walling), not because of concerns about the screw's strength.
    – FreeMan
    Commented Nov 17, 2023 at 15:11
  • I've never once had a drywall screw break.
    – LarryBud
    Commented Nov 22, 2023 at 15:25

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