I'm not a woodworker of any kind but I am building a desk from a laminate kitchen worktop measuring 3000x600x38mm (L x W x T) but I only want the legs on the side. I don't want to have to put an additional two legs in the centre. How could I reinforce the chipboard without adding more legs? Could I just put a 30x30x3000mm (W x H x L) piece of angle iron on the back edge? I want to eliminate the chance of the centre dropping over time or even immediately. It's not going to be holding a lot of weight near the centre: just a monitor, keyboard and mouse in the centre. However on either side there are going to be 3d printers but as they are near the legs there shouldn't be an issue with bowing.

This is the sort of piece I am thinking of buying, and it looks like this in section: Chipboard section

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    Maybe show a little drawing of what you have in mind. You can look at how flat-pack furniture is designed to see how composite materials are used. It also really depends on the kind of composite you are using. It sounds like low-density particleboard, but maybe a photo of the material you intend to use might help. In general, you'll find that this material has to be supported by dimension members of some sort. Especially 3m of the stuff. Even plywood would have to be supported. – jdv Nov 26 at 16:38
  • This is what I intend to purchase diy.com/departments/… – Nathan Martin Nov 26 at 16:44
  • And this is an example of the cross section of the material oldlami.com/images/worktop-chunk.png – Nathan Martin Nov 26 at 16:45
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    You can edit the question and put images and links inline. Comments can be deleted, and are not strictly part of the Q&A on SE sites. – jdv Nov 26 at 16:52
  • Chipboard is notorious for not even being able to support its own weight (!) so I'm fairly sure just in principle this won't work as you'd like. Although I do think you want to ask this of a UK-based kitchen installer to get input based on real-world experience I'm fairly confident that nearly a 3m span unsupported on the front edge will sag a bit at the front in time — a friend has two stretches of unsupported counter in his house (much shorter than your proposed span) and both deflected downwards over time, enough to cause difficulty in sliding in the white goods underneath, so a fair droop. – Graphus Nov 26 at 18:24

It looks like you are planning to use a (partially?) veneered low-density particleboard.

3m of length of almost any material is going to need support, and that is just as true for this stuff.

Even a wood plank top would need an "apron" or support system of some kind at this size. And the longer the span, the beefier the support has to be. Just look at almost any larger 4-legged table.

Now, the material you link to looks like it is at least partially wrapped veneered material (i.e., the usual sort of LD veneered particle board used for countertops) but even if it was fully wrapped (which is a fair bit stronger than the stuff with only a veneer on the top and sides) there is still only so much the material will span.

Ikea, et al, get away with this by

  • Keeping overall lengths down, and using actual wood for spanning/support
  • Using steel aprons and supports for larger dimensions
  • Letting the smaller, cheaper items just fall apart after a few years, or a few moves

For what sounds like a digital workstation of some sort (which is going to take a lot more abuse than you suggest!) I'd suggest a metal or wood apron and maybe even a dimension piece of some sort along the bottom centre that ties to the side apron pieces. You could use angle-iron, but since we don't know the size of what you want to use you might have to do a little homework.

The idea is that you want some material that is resistant to deflection, and that ends up being either wood support "beams" (i.e., with the force being applied along the thinner side), or some sort of metal beam (a folded box of metal, or an L- or I- beam). The latter is how Ikea designs their largest SOHO task desks.

I actually would not generally recommend low-density particleboard for a top. That being said, the stuff you want to use (if it is fully wrapped by a veneer), will be a little better at spanning, but it will still need support. Ikea, et a, use these sorts of veneers, too, and they are surprisingly light and strong (though, often a honey-comb material inside, not LD board). But they could not span 3m unsupported with it.

So if you do use this stuff, think about how countertops are installed, with plenty of supports taking the forces to the floor. You either have to take those forces directly to the floor, or distribute them along spans that direct the forces to the legs and then to the floor.

I think this is going to be a heavy desk, so make sure you design it to be taken apart!

Based on a late comment by the OP, aluminium scaffolding would be very appropriate as a task table base (it can be hard to level; make sure you get adjustable feet) though I'd make sure I used more support for any composite material unless it was very strong and stiff. Plywood/veneer (e.g., the nice Baltic birch plywood the big box stores use for furniture) would be perfect. In a pinch, thick enough chipboard or OSB would probably be fine for that span as well. But if you want a smooth top, chipboard is not going to work.

Of course, scaffolding is intended to be used with the appropriately thick boards; so that material would work. You wouldn't even have to join the boards to make a complete panel, but this depends on how flat and continuous the top has to be.

As per the comments, counter top LD particle board can't even support its own weight. So whatever you use would have to have support every 4ft or so.

To recap:

  1. Figure out what sort of material qualities you need. Does it need to be nice and flat? Does it need to take screw without tearing out? How are the sides going to be finished. Unfinished edges get tiresome real quick, BTW.
  2. Consider how the dynamic forces at the top need to be addressed. The taller the table, the more moving mass at the top will need to be dampened. Two 3D printers going might actually set up some oscillations that will make your prints come out wonky. Make sure this thing is as stiff as you can reasonably make it. I don't know how stiff scaffolding stays, since I've always used it after years in service where it is strong but moves quite a bit. YMMV.
  3. Select a material that give you the qualities you need at the dimensions you need.
  4. Design a support that will give the material you choose the stiffness it needs.

The reference desk I have in my mind is a similarly sized desk from Ikea I use as my workstation. It uses a powder coated boxed steel apron with integrated adjustable steel legs and Baltic birch veneer on top. It has been in service for almost two decades and still very stable.

  • So what about something like this... goo.gl/W4atqg its made with uk standard 48.3mm scaffolding poles and a few right angles and tees i would assume that it would be rigid enough for the job as it is designed for heavy weights and a lot of pressure – Nathan Martin Nov 26 at 16:59
  • If you are ok with the centre stretcher and the H-config, then it should be fine. I mean, the load-bearing material is designed to keep tradesfolks from falling to the ground. My guess is that your table top will deflect in the centre without one or beams across the top. Again, think of how a countertop is supported. That is, the metal stuff you show is intended to be used with quite beefy dimension lumber as the top. – jdv Nov 26 at 17:11
  • +1. FYI the stuff the OP intends to use almost certainly has no laminate underneath based on its price point. Most lower-end melamine counter material in this part of the world the surface laminate tends to wrap over the front edge and then continue to cover just a narrow strip of the flat underside (2cm?), with often the rest of it being bare chipboard. – Graphus Nov 26 at 18:34
  • @Graphus, yeah. I couldn't quite tell from the picture. Full-wrap veneer is rare, so I should have known. I'll fix the answer. – jdv Nov 26 at 18:37
  • I can confirm that it doesnt have laminate on both sides but it has got a resin like coating on the underside its not bare chip – Nathan Martin Nov 26 at 18:42

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