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Here is the screw selection table for the Kreg Jig (R).

enter image description here

This table stops at material thickness of 1.5" and gives screw length of 2.5". I am sure that Kreg is aware that material thickness can be more than this like in a 4x4. How in the world is a person supposed to drill pocket holes into thicker materials and what size screws should be used?

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  • You're not supposed to. You're misapplying something which works well-enough for what it was made to do to something it wasn't made to do, and won't do well.
    – Ecnerwal
    May 17, 2023 at 1:32
  • So what is the solution then?
    – quantum231
    May 17, 2023 at 13:00
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    Depends on the application. Half-lap, mortise and tenon, bridle...
    – Ecnerwal
    May 17, 2023 at 13:22
  • This can't be answered without supplying at least some detail about what it is you're trying to build or what it is you're trying to fasten together. Once we know that a solution can be suggested.
    – gnicko
    May 17, 2023 at 20:24
  • I intend to create a frame using wood. This frame will be rectangle, long side vertical. There will be 1 vertical wood in the middle for extra support. I shall mount "tool wall" on this. This is a recangle metal/plastic plate with holes. We put hooks into holes and then mount tools on them. I cannot mount the tool wall directly on the wooden shed wall. Therefore, I shall make a wooden frame and then mount the tool wall on it and then put it on the end of my shed. Does this make sense?
    – quantum231
    May 17, 2023 at 22:50

2 Answers 2

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It really depends on what it is that you're trying to connect together. We'd need to know more about what you're building to answer fully.

Here are a couple things to keep in mind:

  1. The "material thickness" alluded to in the chart above is primarily concerned with the thickness of the piece you're attaching to something else, not the piece it's being attached to. Attaching a 3/4" board to a 4x4 wouldn't require screws any longer than attaching two 3/4" boards together, but in a situation where you're building with 4x4s, you may need a method that's more robust than pocket screws.
  2. Kreg didn't "invent" pocket screws and if they don't make screws long enough for what you're trying to do, there's no reason why you can't just use "regular" screws to make the connection. Pocket hole screws have been around for hundreds (thousands?) of years. You just need to install the screws at about a 15-degree angle (give or take) to have the screws emerge from roughly the center of the board that you're trying to attach and continue into the board that you're attaching to with enough length to make a strong connection.

Pocket hole screws are a viable method of connecting boards together but they are wildly over-used or over-implemented these days in situations where there are much stronger (and arguably easier to do) alternatives. Pocket holes tend to "lose their grip" in situations where stress is placed on the joints--like movement, seasonal expansion/contraction, etc. The screws can pull out, the thin pieces of wood that the screws are in also is prone to splintering or breaking, and there isn't much side-to-side strength either.

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  • I will make a frame using wood. Then, I will mount a "tool wall" on this frame.
    – quantum231
    May 17, 2023 at 22:51
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    Sounds good... What kind of wood? What are the dimensions of the "tool wall" and what are the dimensions of the frame and the wood planks you want to use? What are you doing with 4x4s? Can you post a photo or sketch of what you want to build? What tools and experience to you have available?
    – gnicko
    May 18, 2023 at 1:49
  • And again, this sounds like something where you will get more and better advice in the woodworking stack than here in the home-improvement stack.
    – keshlam
    May 19, 2023 at 15:06
  • @keshlam Can't be answered on WW without more details either.
    – gnicko
    May 21, 2023 at 15:49
  • @gnicko: True, but that's still the right community to ask, I think. Unless we're talking about using pocket screws specifically for home improvement.
    – keshlam
    May 21, 2023 at 19:51
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IF you can get long enough screws with suitable heads, which Kreg may not offer, the table should extend along straight lines.

Note that all of this is adjusting to try to keep the screw connection in the center of the board and to put as much thread into each side of the connection as possible without blowing out. It doesn't absolutely have to be there, that's just going to give you the strongest connection.

Note too that for larger pieces, pocket hole joinery might not be a wise choice. Like anything, it has both strengths and weaknesses.

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  • So if pocket hole stuff is not supposed to be used, what is the correct alternative?
    – quantum231
    May 17, 2023 at 13:01
  • What is "correct" depends on what you are actually trying to build.
    – keshlam
    May 17, 2023 at 13:22
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    That's the key--it doesn't have to be centered. I'd just use the 1-1/2" numbers for everything from there up, or use the numbers for the longest screw length you have on hand.
    – isherwood
    May 17, 2023 at 20:21

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