Best screws for plywood?

Discussion in 'Off Topic' started by MichaelD, Feb 22, 2008.

  1. MichaelD

    MichaelD Lifer

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    I'm making a plywood box with shelves...that's basically what it is. Box will be 26"w x 24"d x 14"h.

    I will be joining the plywood pieces with simple butt joints. I don't have access to a biscuit cutter router or even a table saw, so anything better is out.

    I'm using 3/4" plywood. What would the best screws/length/diameter be? Drywall screws? Sheet metal screws?

    Thanks.
     
  2. Cienja

    Cienja Senior member

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    1.5" grabbers maybe? Although the drywall screws would probably work too.
     
  3. Vette73

    Vette73 Lifer

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    Wood screws but also put some wood glue on the joints. Wood glue used correctly will have a stronger bond then the wood itself. If your project will not get a lot of water/wetness then any basic wood glue will work. If it will see a lot of water contact then tight bond 3 is what you want.

    Also biscuits don't add strength that well they are mostly for aligning up you project to make sure it is connected correctly, the glue is what does the bonding.

    Don?t under estimate the power of a good glue bond on wood. I made a step ladder with nothing more then glue and clamping it together to hold.
     
  4. runzwithsizorz

    runzwithsizorz Diamond Member

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    I would go with the drywalls, the wide threads will grip better, and are less likely to split the plywood, especially when predrilled. They won't rust either. Length 2", dia. n/a .
     
  5. runzwithsizorz

    runzwithsizorz Diamond Member

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    Good point Marlin!!! I should have thought of that. I use a hot glue gun myself.
     
  6. Howard

    Howard Lifer

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    Drywall screws + glue. Just glue will work if you use clamps.
     
  7. MichaelD

    MichaelD Lifer

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    Great. Thanks guys! I will use glue and at least 1.5" drywall screws. This box will not see any water at all.

    Truth be told; it will be a server rack for my house. But without any rack rails. :eek: I'm on a budget.
     
  8. EagleKeeper

    EagleKeeper Discussion Club Moderator<br>Elite Member
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    If possible consider putting in a 1/2" block at each corner on the inside.
    That will allow you to go from the plywood to the block and secure it stronger.
    Fat thread wood screws will be your best option.
     
  9. reeserock

    reeserock Member

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    Drywall screws seem to be brittle compared to wood screws. Not sure if that's an issue in this application, but something to keep in mind.
     
  10. MichaelD

    MichaelD Lifer

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    "Fat thread?" :confused: As in coarse-thread screws, aka drywall?
     
  11. 911paramedic

    911paramedic Diamond Member

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    Drywall screws break like reeserock said.

    Use self-tapping wood screws (they drill their own hole, avoiding any wood splitting) and wood glue. Simple job and no extra steps involved.

    I built this with self-tapping screws and glue only. (and a nailgun for the trim)

    Far left, six screws and glue hold on the leg.

    Desk finished, without stain.

    The only thing that needed a block was that vanity panel in the front, because there was no way to screw it on besides that method. (And you need a special jig for drilling those guide holes at the preset angles) If you can screw directly into another piece, and use glue, you are good to go.
     
  12. EagleKeeper

    EagleKeeper Discussion Club Moderator<br>Elite Member
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    Coarse Thread - but not drywall
    3/8 to 1/2 inch head

     
  13. waffleironhead

    waffleironhead Diamond Member

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    FYI, there are coarse AND fine drywall screws.
     
  14. Squisher

    Squisher Lifer

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    From your description you'll be screwing into an edge of a piece of plywood. When you do the layers will have a tendency to disintegrate and often the plywood will just de-laminate a little leaving a bulge where the screw is.

    I think I'd try to stabilize the edges first by painting them with some wood glue thinned down a little, then letting this dry and when I went to put the screw in I'd sandwich the plywood on each side with a couple of scrap pieces of wood held securely in place with a c-clamp to keep it from bulging.

     
  15. alkemyst

    alkemyst No Lifer

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    Yeah you really cant screw into an edge of plywood.

    Get some strips of wood to sit the shelves on and screw into that
     
  16. MagnusTheBrewer

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    Don't use screws. Use dowel rods and wood glue.
     
  17. PottedMeat

    PottedMeat Lifer

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    Oooh thats nice work.

     
  18. Modelworks

    Modelworks Lifer

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  19. Jeff7

    Jeff7 Lifer

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    What do you use to make the top of the desk perfectly flat? What kind of wood is that? Looks nice.
     
  20. JeffreyLebowski

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    Deck Screws FTW. Dry Wall screws are for just that, dry wall. though with what it sounds like you are making the weight shouldn't stress even a drywall screw, but I tend to over engineer everything I make. I made a wood foundation for my shed a few weekend sago and to test it I drove my truck over it. Not even a crack in the plywood top.
     
  21. MichaelD

    MichaelD Lifer

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    Wow, some great advice and ideas! And 911paramedic; nice work! Now build me one, please. ;)

    Unfortunately; yes, I'll be screwing into the edge of the plywood. I really don't have any other choice. No brad nailer here. I WAS planning on predrilling the hole with a bit about 1/2 the diameter of the screw. Will that help any?

    I will use four corner braces on the rear of the box to help with torsional stability. There's no room inside the box for blocks in the corners.

    Assuming the wood doesn't split from the screws, the glue and the screws should be plenty strong.

    I'm planning on sitting said box on top of 16" long pieces of 4x4 stock; plenty strong to hold it up.

    There will be on adjustable shelf inside and it will sit on metal dowel pins. I will drill a line of holes in the side panel to allow the pins to be moved up/down. So, said shelf will not help with strength at all.

    Does this sound like it has a remote chance of working, at least? :eek:
     
  22. skyking

    skyking Lifer

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    no worries man. use glue and all the screws will be doing is holding the assembly together until it sets. After that, I'd give the screws about 10% of the total bond strength, and the other 90% will be the glue. If you use gorilla glue, be sure to clean it up while wet, as it is a bugger to get off afterwords.
     
  23. OdiN

    OdiN Banned

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    Drywall screws work great for plywood.
     
  24. HeroOfPellinor

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    Wow you guys are all wrong. LOL. You don't come to a bunch of socially-repressed nerds for woodworking advice.
     
  25. NoShangriLa

    NoShangriLa Golden Member

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    predrill pilot holes will minimize splitting, and get lubricated/coated wood screws (floorings screws tend to be coated) to prevent splitting & breaking screws, or lubricated the screws with paraffin wax.