We had the same kind of shelf collapse as seen here, with less drastic consequences. Collapse

I went and found some nice 90-degree pins at the store, but noticed a small problem when installing.

The pins on the new supports are slightly longer than the old ones (old pins are 5/16", new are 7/16"). So when installed the nice L-bracket doesn't sit flush with the wall. Is this a problem? I'm guessing it should sit flush so that the wall helps the pin-hole support the weight. Pics at the end.

Should I just drill the pin-holes to be slightly deeper (assuming the walls are deep enough - these holes are on built-in shelves so it's not immediately obvious if they are) If I don't do that, should I file the pins down? Look for similar supports with slightly shorter pins? Or are they fine as is?

Pins Sticking out

  • 1
    occam's razor: bought the wrong size, get right size. Jul 23, 2018 at 6:29
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    Just to clarify - the problem is the length of the pin, not the diameter. None of the pins I've seen in store or online give the length of the pin, so I'll have to check various options in person to see if any have shorter pins.
    – aggieTaxes
    Jul 23, 2018 at 7:30
  • Some 5 mm diameter pins I have on hand protrude 8 mm. How far do the ones you have protrude? Jul 23, 2018 at 18:26
  • How many shelves are to be supported with these pins? What is the value of the items on the shelves? Are there heavy items to be placed on the shelves which could fall out with dire consequences? If so, then it might be worth it to fit the shelves in securely and use screws in the holes so that a rap from below can't knock a shelf loose. For this latter to work three screws per shelf might suffice. Jul 23, 2018 at 18:39
  • 24! I replaced all the pins with the L-shaped pins yesterday (96 pins), and found a number of places the previous owners had had shelf collapses, and some where they were about to happen... patched up the ripped MDF with wood putty or wood glue, depending, just for looks...
    – aggieTaxes
    Jul 25, 2018 at 6:03

2 Answers 2


The same shape shelf pins are available in the same size you need. The pin is measured at the part that goes into the hole, some are 5MM, some are 1/4" I have never seen 7/16" or 5/16"

  • Just to make clear, the problem isn't the diameter of the pin, which in this case is 5mm, but rather the different lengths of the pin. The pins sold in stores don't specify the length, and they just happen to be different.
    – aggieTaxes
    Jul 23, 2018 at 7:33

You could add little shims to the slightly long pins. These would support the pins against the wall and keep them level. Galvanized plumbers suspension "tape" would make good shims and have holes already drilled. Or one or two washers on each pin might do the job. Then again too much shimming might make the space between the side pins too tight for the shelves to fit.

Another fix might be screws in the holes, if you don't plan to move the shelves once you have them set. Of course, if these shelves are fine wood or just good shelves in a fine shelf unit you may not want to makes holes in the bottoms. And if the shelf is heavily loaded, then such screws could have significant pull out force on them.


The 5 mm dia pins I have have a plastic shelf support end with the shelf bottom above the level of the pin. They are not L-brackets. I am sure that the all metal "L-bracket" makes a more secure support, and if the fit is tight enough so that drilling the holes deeper is necessary, then this is thing to do.

  • I really like the shim idea, particularly the washers. The shelves are in our new house and looked oh so nice; upon collapse we discovered they are well-disguised particle board, so I will likely also be adding screws to any of the shelves with heavier loads.
    – aggieTaxes
    Jul 23, 2018 at 7:33
  • I would discourage the use of washers or other types of shims. Check carefully to see if drilling the holes deeper is an option. If not then grind the pin length down. BTW the old pins with just a 5/16" pin penetration is really not ever an acceptable type of application into particle board. I would never use short pins like that in anything but a hardwood like solid oak, ash or cherry wood.
    – Michael Karas
    Jul 23, 2018 at 15:04
  • The fun thing about this sort of question is that it is easy to try some things and see if they work. One of the constraints I sometimes impose on myself is to use materials on hand (no special trip to the homestore.) Putting shims between the pins and the side wall might make a very strong and secure support if the shelves would fit just snug but not force the sides out. FMI, how long are the pins on these all metal supports you have? I have a packet of supports with 5 mm diameter pins, and these pins protrude 8 mm. Jul 23, 2018 at 18:13
  • Having proposed shims I have become obsessed with how to implement this. Try paper card stock (say from junk mail) and make the holes with a paper hole punch. Jul 23, 2018 at 18:36
  • Curious, what do you mean by force the sides out? Some shelves had a hard time fitting in the slightly reduced width, and I did have to drill the pin holes just a bit deeper to get them to fit in the L-brackets.
    – aggieTaxes
    Jul 25, 2018 at 6:07

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