what is the strongest joint between using such fasteners https://www.core77.com/posts/27725/Death-to-Cam-Lock-Nuts-Flatpack-Hardware-That-Will-Hopefully-Become-Obsolete (ikea furniture ones), and the kreg screws for pocket holes ?

Using a 90 angle joint between a vertical and horizontal panels, is there a winner resisting better to both: a pullout of the horizontal panel in the vertical direction, a push to the left/right of the vertical pannel (in a tangent/horizontal direction) ?

  • Hi, welcome to StackExchange. There's a clear winner here in terms of strength, but these are not really equivalent fastening options, with one being take-downable (and within reason, indefinitely so) and the other typically not, so is there a specific reason for you wanting a comparison between them? There are of course numerous other ways to join two boards/panels at 90°! Many of the others also surpass the cam locks for security, but again at the cost of not creating a knock-down join. – Graphus Jan 8 at 10:44
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    It's also worth pointing out that not all knock-down fasteners are created equal. Even for cam lock connectors there is a huge difference between well-made hardware with tight tolerances and the cheap ones you find in most budget furniture. Also, knock-down hardware gets a bad reputation because it's typically used in particle board, which doesn't hold any kind of fastener very well. In hardwood or a quality plywood knock-down connectors can be "strong enough" for most uses. – SaSSafraS1232 Jan 8 at 17:33
  • Also, you tagged the question with "plywood", but nowhere do you actually state that you're using these in plywood. This does make a difference, as pocket holes will be weaker and cam-locks stronger in solid wood due to the surface area of end-grain that would pull out in a failure. (I.e. pulling the screw head out vs the whole barrel of the cam-lock.) – SaSSafraS1232 Jan 8 at 17:37
  • @SaSSafraS1232, I'm not sure if the cheap cams are inherently bad because of their cheapness, as long as they are capable of tightening on to the rod/bolt that intersects with them (obviously not a given, but IME they do tend to do this pretty reliably). What I have seen a lot with cheaper furniture — I'm looking at you Ikea — is the holes drilled for the cams are hardly what you'd call uniform! Just like with the dowel holes, the very inconsistent drilling by itself does a lot to undermine the potential for initial rigidity and long-term tightness. – Graphus Jan 9 at 14:13

In the absence of clarification from the OP I'll Answer this with a given set of assumptions.

The basic answer here is pocket-hole screws, and by a pretty large margin.

It's not simply that the screws themselves are so much more secure than a steel rod of some kind intersecting with a cam1, it's that pocket-hole screws tend not to be used in isolation. The norm for screw installation in pocket holes (and actually much assembly of furniture using screws) is to both glue and screw. And the glued joint does a lot of the heavy lifting when it comes to joint strength, particularly so in solid wood which edge-glues far more strongly than plywood does.

In addition to outright strength, there's the issue of flex and other movement in a joint. A joint that can shift even slightly is always at risk of becoming looser over time if it's stressed, but even from normal day-to-day loads being applied (minor stuff, like leaning forward into the surface of a desk as you work at it), as well as from seasonal wood movement2.

And this is precisely why screws are rarely used by themselves in quality furniture work; not necessarily high-end stuff, just anything intended to last. Because they allow for some movement they tend to wallow out their own holes and you enter into a cycle of damage — movement leads to wallowing which allows for even more movement, and so on.

1 At least in a fresh installation, where everything is done well.

2 So just sitting there unused something can become a little less tight and solid than when it was last used.

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