Pocket hole - flat surface to flat surface

[Darby Smith]

Can you use a pocket hole to attach a flat surface to another flat surface?

I'm wanting to screw two 3/4" sheets together and wondered if I can use my Kreg jig somehow to do that? Two sheets, laying one on top of the other, so if I had a 4x8 sheet of MDF, 3/4" thick, it would now be 1-1/2" thick, screwed together with pocket holes.

Doable? Or are pocket holes only for edge joinery?

[Cary Falk]

I don't know why you would want to do it. Just use 1 1/4" screws and screw it directly. Less work and would probably hold better.

[Art Mann]

That is not an appropriate use of pocket hole joinery. However, if you want to use pocket screws, just shoot them straight into the plywood. They will certainly hold two pieces of plywood together. I would probably use drywall screws if I were going to laminate two pieces of plywood in that way because I would countersink them to provide a smooth surface on the plywood. Glue and a small number of removable screws to provide a clamping force would be even better.

[Darby Smith]

Ok - that's what I had assumed but wanted to make sure I wasn't missing something. Yes, I want to use the jig, but for what it's intended purpose is. I was figuring I was making it more complicated than what it needed to be, but figured if it did actually serve that purpose (and I couldn't figure out how), that it was easy enough to ask. :)

Thanks for the quick responses.

[Lee Schierer]

The problem would be clamping the jig on a 3/4" thick piece of material that is wider than just a few inches that would fit in the clamp. Even if you could clamp it the geometry of the pocket hole would be the same as just drilling a small counter bore at an angle near the edge of your work piece and I suspect that the screw tip might go through teh piece being attached. As others have noted it would be far simpler to just drive the screws in directly with no hole.

[Loren Woirhaye]

I do not think pocket screwing would draw the parts together as well as straight in screwing with a screw meant for power driving. You'll notice on old fashioned wood screws the shank is unthreaded below the head and larger than the thread portion. This is so it can fit though a hole in one part and the threads engage in a smaller hole in another part and the parts are drawn together tightly thus.

[johnny means]

I do not think pocket screwing would draw the parts together as well as straight in screwing with a screw meant for power driving. You'll notice on old fashioned wood screws the shank is unthreaded below the head and larger than the thread portion. This is so it can fit though a hole in one part and the threads engage in a smaller hole in another part and the parts are drawn together tightly thus.

Actually, pocket screws draw pieces together very well. Even without any pre-drilling. The self drilling tip creates the hole needed to allow the unthreaded portion to slip through. The threaded portion will keep powering through your material until the head won't allow it to go any further. I've countersunk 2.5" pocket screws clear through a 2x4 in order to reach a pair of 2x4s behind it, without any predrilling. Traditonal wood screws are terrible at this because they only engage at a specific depth and the small tip cannot pull the larger shank behind it.

[lowell holmes]

Pocket screws will work, but my preferred method are flat head tapered wood screws.
I drill the pilot holes with tapered bits sized to the screw I'm using. They produce incredible holding power.
Lee Valley is the source for my bits.
A #12 X 2 1/2" wood screw will hold rocking chair rockers on very well.

[Brian Holcombe]

Are you doing this with the entire sheet or a smaller portion? I would consider gluing.

[Darby Smith]

It's been glued and screwed from the bottom. We put the first one on, countersunk the holes and bolted it to the frame then glued and screwed the top on.

It wasn't anything fancy, just two pieces of 5/8" cut to fit on a frame I bought from Army Surplus for $12, that and four wheels from Haborfreight and I've got a nice movable workbench. Had to cut some of the frame to lower the height and make room for the wheels, and then weld the wheels in place.

Was just excited to use the jig, but as noted, this wasn't the job for it.

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