Bearing Capacity of Shelf Pins
Informal testing indicates that they are strong. July 11, 2013
Question
We have a custom shop and I have always thought the 3mm look much more discreet especially on open casework. I ordered the "spoon type" pins and upon arrival I am wondering how much weight such a pin can carry. I tried to bend one with some snips and it bent at the pinching point, not the point where pin meets spoon (weakest point in theory). I’m just wondering how these will compare to 5mm spoon type pins.
Forum Responses
(Cabinetmaking Forum)
From contributor D:
If your holes are drilled correctly and the shelves are sized correctly I don't think you have to worry. You’re using leverage to try to bend the pin but that's not the same force it will encounter in service. Instead it will rely on shear strength to support you shelves. So instead of bending the pin, clamp it in a vice and try to shear it in half with weight. In reality the cabinet sides will fail before the pin does, unless of course it's a really poor quality pin.
From the original questioner:
Yes that makes sense. The pins are from Hafele so I’m guessing the quality is ok. I remember from my carpentry days that 16d nails’ shear strength was something like 1200lbs. That doesn't really help though. Maybe just sitting on a shelf could test it.
From contributor L:
I doubt that the pins would fail. Make the shelves a fairly snug fit so they touch the pins as close to the sides as reasonably possible. The looser the shelf fit the more pry is put on the holes in the case and the more likely to smash the edges of the holes. 5mm pins are pretty much the standard and have a lot bigger bearing area than 3mm. I’m not so sure about the discreet idea.
From contributor R:
The key is that the shelf is only about 3/32" over all undersized. The issue will be if the shelf is too short or if the vertical span of the cabinet sides is over 48" without a fixed shelf. Such as a tall book case without a fixed shelf as the sides can start to crown out allowing the shelf to slip off the 3mm pins.
From the original questioner:
I finally received the drill bits and the pins. After a test using hand/body pressure, it seems evident they are more than adequate. I can’t see why the fit is so crucial for the shelf. There would have to be so much weight on there for any kind of deflection or the force of the pin crushing wood and the shelf slipping off. The holes are by far less of an eyesore than the 5mm for open casework.
