Why Both Glue And Screw? - Woodworking Talk - Woodworkers Forum
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post #1 of 10 Old 06-17-2016, 08:52 AM Thread Starter
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Why Both Glue And Screw?

Iíve seen photos in magazines, and YouTube videos showing that a glue joint when put thru torture tests, the wood always breaks and not the glue joint. Iíve seen examples in a press, folks jumping on the joint, being run over by a pickup, etc.

So why bother using both glue and screws? Yes, I get it that a few well placed screws are your clamping. But watching a ton of YouTube videos, I see a lot of folks glue something up but then they put a Ďgazillioní screws along the joint as well. A while ago I saw someone with a board glued to another at a right angle that was at least 2í long. And then they put in screws about every 2 inches along the jointÖ

Isnít that overkill?

Whatís your theory/workflow when using both screws and glue?
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post #2 of 10 Old 06-17-2016, 09:04 AM
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Just MHO but the screws add a little strength to the joint as well as providing the clamping.

Bob making sawdust in SW Louisiana
with a EX-21
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post #3 of 10 Old 06-17-2016, 09:25 AM
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If you're using plywood, then I believe you need the screws.
I posted this link on a thread about glue tests. The main thing I got out of it is, plywood glue is weaker than anything you'll use on the joint.


The screws are necessary to keep the plywood, itself, from separating.
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post #4 of 10 Old 06-17-2016, 09:31 AM
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A lot depends on the material and what you are building but for the most part the screws just pull the parts together better enabling the glue to work correctly. A lot of times if you have enough clamps screws are not necessary. The exception would be end grain joints like the corner blocks holding a chair together. On that application screws are very much necessary.
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post #5 of 10 Old 06-17-2016, 09:34 AM
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if there is a wood to wood joint, the glue will be the #1 fastener. however, there are other factors: long grain to long grain - glue and clamps is all that is necessary. ANY other joint, such as long grain to end grain, or other types of wood products - the glue may not hold because of expansion and contraction, atmosphere (indoor/outdoor). so mechanical fasteners are used as a second bonding method.


but with care, I have successfully glued edge to edge of 1/4" plywood, and end grain to end grain hardwoods. clean cuts, good glue and clamping. I would suspect they would not survive long in a press test.
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post #6 of 10 Old 06-17-2016, 03:28 PM
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I use screws & lag bolts in a dry joint with damp/wet wood, fully expecting everything to shrink in my Frankenfurniture. I was right.
The legs are a bit wobbly, tighten the screws. Maybe this coming winter, I'll drill out the screw holes at 3/8" and peg and glue the joints.
Its a carving bench 12" x 48", built entirely out of 4x4 western red cedar (crappy small-log stuff, far harder than the fancy deck & furniture grades.) Easy shopping when the mills are side by side and 20 minutes from the house.
A decade ago, I built myself a simple bedside table. Dimension lumber, nothing fancy. Glue, dowel pegs and clamps. Clock radio, some books, that's it for load. It will last forever.

No, I have no idea why builders use both glue and screws, especially if the unit takes little load.
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post #7 of 10 Old 06-19-2016, 08:13 AM Thread Starter
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Lots of good reading above. Thanks for the posts, they are very informative. I enjoyed the glue test link, too.

Thanks folks! :)
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post #8 of 10 Old 06-19-2016, 02:43 PM
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Belt and braces

Last edited by rubberduck; 06-19-2016 at 02:45 PM.
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post #9 of 10 Old 06-24-2016, 11:37 AM Thread Starter
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Hi Everyone,

While 'surfing' woodworking videos, I found a glue test that was pretty interesting:

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post #10 of 10 Old 06-28-2016, 09:22 AM
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I use screws and glue on table braces. Don't have to clamp the braces down and I can go ahead with sanding the next grit. I put these on with the table bottom sanded to 60 grit and the brace also at 60 grit. I use a small loop of glue around the perimeter. Just enough away from the edge so none squeezes out.
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"wood does not do well outside.....well....except for trees"
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