Glued and Screwed Bench top

[SixPointEight]

When I first built my bench, I used a single 3/4" plywood for the top, with a 2x4 "stud" in the center for some additional support. This was enough for the Lee Turret I was using. Now I've upgraded to a Dillon 550, and while I'm at it I was thinking of adding a second sheet of 3/4" plywood underneath my top one, to provide a little extra strength. Often I see people saying they "glued and screwed" their plywood tops together. The question I have is what glue to use? I've seen reference to regular wood glue, subflooring glue, and even Gorilla glue. My first guess is either wood glue or subfloor glue, as they're both meant to glue wood to other wood. Does any one glue provide any benefits over another?

Additional question as to the process. Do you find a flat spot in the garage, spread the glue on one surface, then lay the other board on top with a bunch of heavy weight (brass and bullets) for 24 hours to let the glue set, then drill holes and attach to the bench frame? Or do you align the pieces, drill your holes, apply glue, then screw to the bench top and let the screws clamp the wood together?

[chrometip78]

I used Titebond and two layers of subfloor plywood. Been great for about 10yrs and really stiffened up the whole bench.

The more I used Gorilla glue, the less I like it for most projects. Really have to be able to clamp something together well to be a good option.

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[JackEllis]

Titebond. Forget about the others.

[SixPointEight]

I'm guessing Titebond 3? The strongest and longest working time

[TheZouave]

As a professional woodworker, and having built multiple tables like this...

Titebond I or II would be my #1 suggestion. Either will work fine. Use old gift cards to spread a thin, even layer, then locate your two boards, and screw from the middle outwards, it'll squeeze out excess glue that way.

[TheZouave]

Titebond 3 is a different formulation than 1/2. I'd avoid it for this project. If you have access to it, titebond makes an Extend line, with a longer working time. But I wouldn't bother with III, personally.

[NukleusX]

Krazy glue. Lots of it.

[TheZouave]

Sorry, krazy glue won't come anywhere near the strength of a properly done joint with wood glue. It'll eventually become brittle as the wood moves, and your working time will be under a minute.

[SixPointEight]

As a professional woodworker, and having built multiple tables like this...

Titebond I or II would be my #1 suggestion. Either will work fine. Use old gift cards to spread a thin, even layer, then locate your two boards, and screw from the middle outwards, it'll squeeze out excess glue that way.

This seems to support lining them up, pre drilling, then applying glue and using the screws to clamp it down. I ought to be able to handle that

[TheZouave]

Exactly. Use screws that have a short length of straight, unthreaded shank, so you get actual clamping force, you need the screw threads to not engage with the top surface to get the best results. If you do it right, you can remove all the screws afterwards, they won't be remotely necessary.

This seems to support lining them up, pre drilling, then applying glue and using the screws to clamp it down. I ought to be able to handle that

[NukleusX]

Sorry, krazy glue won't come anywhere near the strength of a properly done joint with wood glue. It'll eventually become brittle as the wood moves, and your working time will be under a minute.

Spoken like a true woodworker would speak to a plumber.

I was joking :P

[SixPointEight]

Exactly. Use screws that have a short length of straight, unthreaded shank, so you get actual clamping force, you need the screw threads to not engage with the top surface to get the best results. If you do it right, you can remove all the screws afterwards, they won't be remotely necessary.

I'm using 3" decking screws holding my plywood to the bench frame anyways. They happen to have a 3/4-1" unthreaded shank, so they should be perfect

[NorCalFocus]

This seems to support lining them up, pre drilling, then applying glue and using the screws to clamp it down. I ought to be able to handle that

If you don't have one, get a pre-drill/counter sink bit. It will make your life a lot easier.

[sofbak]

If it were me, instead of adding another full layer on top I would look at reinforcing the area around the press from underneath. Angle iron that catches the existing bolt pattern or maybe a smaller ( 2' x 2'?) piece of plywood or 1/4" steel plate maybe.

[TheZouave]

If you don't have one, get a pre-drill/counter sink bit. It will make your life a lot easier.

Definitely this ^^. If you're using deck screws, you'll want one of these. I'd actually recommend a slightly shorter screw, a 1" smooth section, if you're putting together two 3/4" sheets, removes a third of you thread engagement, plus it'll blast out the other side. Which can be fixed easily with the screws removed and a sander, but that's extra work, versus just finding the right screws at the local HD/Lowes/hardware store. I personally really like pocket hole screws with a square drive and a pan head for the type of project you're doing, but deck screws work fine too.

My process is as follows:
Mark along edges the interval you want your screws at.
Strike lines using a chalk line or T-square.
Clamp surfaces together - I leave mine a little large so I can trim down later using a skilsaw with a guide...
Drill through top and 1/8" into bottom board -keeps screws from pulling up a little mounds of material and creating voids in your glue surface.
Separate top and bottom piece, quick pass with random orbit sander to knock down any high points.
Blow clean with compressed air.
Apply and spread glue - old gift cards work great for getting a relatively even coat on/pushing around glue.
Lay dowels along the surface so rest the top on while you get it positioned correctly.
Remove dowels, re-check position, then begin screwing down. Start from the middle and work your way out. An impact driver will make things go way, way better.
Let it dry overnight, back your screws out, and you're good to go!