Strips with internal mounting holes are a pain, and guaranteed by design to not mount securely
We all have major and minor annoyances and nuisances to deal with when it comes to design shortcomings. Here's my admittedly petty one: the mounting holes of the ubiquitous AC power strips.
A little background: when you need more AC outlets, the solution is simple. You buy an AC power strip, generally with six outlets, priced from $3 (on sale or as a store teaser) to perhaps $10. [An aside: in the US, all these strips carry the UL-approved label for safety, but sometimes, you do have to wonder how genuine that label is. . . ] Then you leave the strip loose on the floor, behind the desk, or in the rack, or you go "formal" and mount it to a wall, cabinet, desk side, or rack to clean up the appearance and also enhance the mechanical integrity of your AC-cord nest. And that's where the challenge begins.
Here's why: up to a few years ago, many of these AC strips had external mounting ears, so you could attach them to whatever support you were using. These ears made it fairly easy to attach the strip, either through-hole style with a small screw and nut, or blind style (front access only) to a panel with no rear access.
But in the last few years, almost all the strips I have seen no longer have those ears. Instead, they have keyhole slots cut into the body:
I suspect this is done since it is cheaper. For plastic-body strips, it's an easier molding operation than ears, and needs a tiny bit less raw material where every penny counts, while the manufacturing cost of creating the slots is probably close to zero; for metal-body strips (which are getting harder to find), again, less material, and easier final assembly.
There are two problems with the keyhole-slot mount, however: 1) it's anywhere from slightly harder to much harder to do and 2) it's guaranteed to not work well, no matter what you do.
There are several reasons for this. First, you need at least two flat-head screws with head diameter which is slightly larger than the slot's minor width and slightly smaller than the slot's major width (I say at least two, because you need either two or four screws for mounting, plus an extra one or two screws in case you lose one).
Then you need to measure the distance between the holes pretty carefully, and then spot/drill your mounting holes pretty accurately, which may be especially hard to do in some tight areas. Plus, if you are trying to locate the strip precisely on your panel, you have to make a template which correlates the mounting-hole locations on the strip's bottom side with the strip's overall body size.
OK, you have screws of the right head diameter, and you've placed and drilled the holes carefully, so what's the real problem? Here's where the failure by design comes in. If you tighten down the mounting screws for a firm grip on the installed strip, then you can't "catch" the slots; but if you allow a little slack for the thickness of the strip's body material, the strip will not be attached firmly. With a slight tug on an AC cord in the wrong direction, or inadvertent kick, the strip actually "dismounts" from its screws.
Voila . . . .you are stuck between adjusting the screws too tight to catch the slots, or loose enough to catch them, but then the strip is not securely fastened. Gotcha!
But I am not one to be defeated so easily. In cases where I am concerned about the strip not being attached well enough for the situation, I have used two methods to overcome the deficiency. Sometimes I push a small shim or two between the strip and the panel it is on as a wedge, thus forcing a tighter fit after installation. Or, I add a small, L-shaped bracket at the end of the strip after mounting it, as a bumper or barrier, so the strip can't be pushed back even if it is a little loose and wiggly. Both methods are reversible, which is also good.
Either solution involves more work and has drawbacks, but at least they give me some level of confidence. But I do miss those obvious external mounting ears, which make every aspect of mounting the strip quicker, easier, and better.
Have you ever had a small, dumb, nuisance problem like this that you have solved, and then used that solution over and over? I'll bet you do. ♦