I'm thinking of putting up some cable-suspended shelves. I know where to get cable and shelf retainers, but I don't know what to use for the shelves, since they have to be quite wide: total width 164cm, and it's only possible (read easy) to put cables at the ends. Worse, their intended use is books, of a fairly heavy kind - say 20-30kg/shelf, for luck.
What material can make shelves 160cm long, 20cm deep, with an SWL of
100kg, with end support only?
Followup: are the shelf retainers (from Flints) up to that load, without being so tight as to damage the cable (I was thinking 3mm cable)?
You could use 18 mm plywood for the shelves. It should be strong enough to take that weight.
The suspension cable is another matter. I take it you are fixing these to either a stone / brick wall, the main timber studs or ceiling joists, but remember that the top lengths of cable are going to take the weight of all the shelves, and so on down the line.
Drilling through the timber at each corner and placing big metal washers around the holes to reinforce them is the best way to go. Under the holes to support the shelves I usually use the metal bits out of screw terminal block that electricians use. They get a good grip on the cable once both screws are tightened up. The terminal block designed for 30 Amps rating has a huge hole in it for very large cables, and the 45 Amps rated ones are f*^"ing massive. So they give quite a choice on which ones to use.
For the heavy weight shelves, try to slip the cable through the clamp twice. As in, push through once, then wrap around the outside of the clamp and push through again from the same direction as the first time, to form a loop on the outside of the clamp.
Slightly abusing the building regs part A appendix would indicate you need something along the lines of a 2" wide by 4" deep piece of structural timber to support that load.
Even for 20Kg to 30 Kg per shelf? I have a shelf here made of one piece of 18mm plywood, and it holds around 25 Kg over its full length of 1,200 mm (1.2 Mtrs). So each shelf made of 18 mm plywood, with the right cables to suspend them from, should hold the books OK, I'd have thought.
Just did exactly this myself. Very easy indeed and look great.
Used conti for the shelves (110cm length, set of 6).
I was putting them in an alcove and used 3 points of suspension - middle (at the back) and the sides (at the front) in a triangle - stops them bending and keeps it clean, simple and cheap. Nice and easy to level too. Steel stranded cable takes huge amounts of weight (I think
3mm takes about 500kg so 1500kg for 3 cables). Flints only had 3mm but I'd have gone for 2mm.
Used the tooth-shaped things at flints to double the cable in a loop at the top to suspend them (3 per cable they advised). Mine are not attached at the bottom (i.e. hanging free) which was probably a mistake. You will need really heavy duty hooks at the top to take the weight. I used some Ikea metal bathroom pegs but they are looking a bit precarious.
Flints have some really nice widgets for gripping the cable under the shelves but they are v. expensive if you are doing a lot of shelves (about 10 quid a shelf). I used the metal bits out of terminal block which work and look fine but is probably not a great long-term solution as I think they could damage (and weaken) the cable (since it runs straight through - the proper ones push the cable against a bend).
You'll need something proper to cut the cable or get it cut to length in the shop - b+q bolt cutters left the strands loose and fell apart on the
4th cut.
For 160 cm I might consider going with 4 cables (2 spaced along the back rather than 1 in the middle) to help take the strain at the top.
This is about teh span that comercial racking tends to use.
Have a look at
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They will sell you parts if pushed.
But the basic idea of strong rolled steel channel with a bit of wood screwed to it to form the surface is valid.
Your enemy is flexure. Unless you go to over an inch thick, your shelves will end up bowed. They must have high stiffness elements bonded to them front and rear. What you use is personal preference. A couple of bits of
2x 1/2" on edge, of decent hardwood? Rolled steel section? Carbon fibre tubing, if money no object? Titanium U section, ditto?
I think I would use hardwood if I wanted a wood finish, and maybe chromed or anodised steel or aluminium U section for a modern look.
But make it a DEEP section. At least an inch for steel, and at least 2 for alumnium and wood.
It's not so much ultimate strength you need to worry about as stiffness - they won't look good if they sag in the middle. I'd use something like a 2x2 frame glued in a sandwich of 9mm ply, but that's going to end up 2.5" thick.
It's not so much ultimate strength you need to worry about as stiffness - they won't look good if they sag in the middle. I'd use something like a 2x1 frame glued in a sandwich of 9mm ply.
It's not so much ultimate strength you need to worry about as stiffness - they won't look good if they sag in the middle. I'd use something like a 2x1 frame glued in a sandwich of 9mm ply.
how about cables through the middles of the shelves but attached to the walls/ceiling at the ends? You'd probably want the fixings quite high above the top shelf for that.
Flints say that's what they are designed to do and they looked good for it to me.
He mentioned a 100kg target which puts him in the number I mentioned. Of course building regs are conservative and allow for poor timber but I would have thought any deflection would look bad. In practice I think a 18mm shelf would be fine if a wooden batten was attached at the back underneath and used to attach to the wall.
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