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I would like to make a small wall mounted cabinet for an audio receiver that I would like to be of specific dimensions. Can I use finish grade 3/4" plywood but join it at the edge using trim screws? I do not have the tools to do joinery.

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    A recommendation: Have the horizontal "shelf" pieces housed within the vertical side pieces. This way, the screws will be supporting weight in shear (through the side, into the bottom), instead of relying on the bite of the threads to hold within the plys (up through the bottom into the sides).
    – FreeMan
    Commented Dec 15, 2023 at 13:34
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    Technically, screws and nails are forms of joinery
    – bowlturner
    Commented Dec 15, 2023 at 13:54

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Yes of course you can join using screws only if desired.

But as you'd see if you look at plywood building advice going way back ;-) adding glue is frequently advised for increasing strength in plywood projects that will be put together with nails or screws. Although not absolutely necessary this is recommend since the hold of screws into the edges of ply is sometimes questionable. If you do add glue refresh the surfaces to be jointed with gentle hand sanding for this reason.

Either way, to maximise the potential hold of screws in plywood remember "the need for pilot holes". It's often expressed this way but actually there are three parts to a correctly drilled hole for any screw that isn't surface-mounted:

  • countersink (or counterbore), to sink the head flush with or below the surface;
  • clearance hole, so there is no engagement of the threads in the first piece;
  • pilot hole to maximise the hold of the screw in the second piece while preventing splitting.

If you're drilling the clearance and pilot holes separately as I do this is easily arranged since you'll just use two sizes of drill bit; if you want to use a combination bit however choose wisely so that the pilot isn't oversized for the screws you're using.

Bonus, 'faux' joinery
Although the basic technique goes back many years (to before the days of Charles Hayward and The Woodworker, who may have popularised the idea), it has come into its own in the modern era with the more widespread use of plywood and other manmade boards.

Peter Millard did an excellent little video a few months ago showing how to form five of the major woodworking joints by building up using thinner ply. See I Make 5 Fake Plywood Joints [video 540] on YouTube.

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  • Remember that screws hold things together by clamping force. Using trim screws, as the OP mentioned, means that the clamp is smaller. Adding glue to the joint would be an extra bonus to help ensure the joints hold together.
    – FreeMan
    Commented Dec 15, 2023 at 13:35

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