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I'm making a shelf from a sheet of OSB, I'm planning to rig it with 4 cables in the corners.

From the answer to this question: How should I attach the cable of a cable-supported shelf? - enter image description here

I get it that I should get an eye bolt through my shelf.

The question is -- what's the necessary size of the washer, and the distance from the bolt's hole to the edge of the board. For 18 mm OSB. Overall load up to 80 kilos. Planned size 1.5*1.2 meters (It'll be accessed from both of the longer sides hence the width). I've used this tool to find necessary thickness.

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    You left out some very important information - what is the size of the shelf, and what weight must it support? Is it just a sheet of OSB or does it have any rails for stiffening? Is there a certain bolt size that you want to use, or is that part of the question?
    – JPhi1618
    Feb 16, 2016 at 15:38
  • For safety sake so not even think of using the 18mm thickness OSB without putting at least framing thickness lumber underneath it to help support it and distribute the load. Follow the example shown in the picture.
    – Michael Karas ♦
    Feb 16, 2016 at 16:04
  • @MichaelKaras , isherwood 's answer and comment contradicts your suggestion. Do you think 18mm is not enough even If I move connection points further from the edges -- it'd make 90cm span, my feeling is I can do pull-ups on such a shelf.
    – Gleb
    Feb 16, 2016 at 16:20
  • @Gleb - My take is that the usefulness if the shelf is severely limited when you would move the cables in as he suggests. His suggestion is OK from a technical merit standpoint but you have to consider usability too. And consider that the framing lumber that you put under the shelf is not that expensive and ends up being the way it should be done anyway.
    – Michael Karas ♦
    Feb 16, 2016 at 22:37

2 Answers 2

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Tear-out of the bolts isn't the primary concern here, even with standard flat washers. Sag is one, and complete snap-off of the sheet corners is another.

If you must use the sheet without a frame, I'd move the cables inboard substantially--cantilever the shelf about 20% of it's length and width. This gives assurance that the corners won't break off and distributes the load much better.

If you can't do that due to the load objects' size or shape, put a proper frame under the shelf. This can be as minimal as lumber under the front and back edges to spread load.

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  • I'm not limited on connection points. So in this case longitudinally I'll make 0.3 meters spacing from the bolt to the edge. What'd be allowed load on the cantilivered parts then?
    – Gleb
    Feb 16, 2016 at 16:06
  • I have no chart for such things, but experience tells me that you'd have to try pretty hard to break that off. Hundreds of kg.
    – isherwood
    Feb 16, 2016 at 16:14
  • I think you'd be surprised @isherwood. It might be strong the day you hang it up, but add to it load, wear and teat, a bit of humidity and/or moisture, and I'd expect eventual failure. OSB is great for a decking or sheathing, but lacks the rigidity and durability of regular lumber, which is why you usually don't see OSB all by itself, especially in a structural usage.
    – BrownRedHawk
    Feb 16, 2016 at 17:08
  • @isherwood Where did this number of 20% came from? What's optimal size of the cantilevered part of the shelf , if the load is distributed evenly throughout the shelf? And what's the minimal distance from the hole to the edge, if the assumption is different?
    – Gleb
    Feb 29, 2016 at 17:09
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Did with a eyebolt above and metal plate below for load distribution. No visible sag at any point of the shelf.

View from below Side view Eyenut of this sickness is probably an overkill given the load, but it's smallest available.

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