Plastic Grid Beam

There is a temptation to extrude beams, but as was stated, a plastic like HDPE just has poor properties for a general purpose beam application. Even something like pine has at least 6x the modulus of elasticity. That’s before you consider voids and other defects. For a specific design, like the hanging chairs in the Maldives project, it is not a driver but for a replacement for 80/20 or steel angle, it is a tough sell.

v3 and v4 won’t extrude enough strength and size to make this work for that sizes as seen in ‘grid beams’. you could only try extruding support material with a shape that could host any of the thousands metal hole beams/extrusions; in a way you still can penetrate (outside can be fine too) the beam with at least 1cm depth on each side per bolt. more or less you will need at least 3x4cm, or better 4×8 cm of such beams to build a structure which can hold 50kg+
on the public market, a plastic grid hole beam is about 5 euro, for 3 meter, and it’s often used in the furniture industry as support material (drawer)

hehe 😉 I’m not against the grid beam concept – I’m just pointing out a few of the problems.  Problems are good – they prompt us to overcome them – but we do need to know they exist.  Known unknowns, and all that 😉

Steel grid beams are popular amongst the folks over at Open Source Ecology. The beams have allowed them to create all kinds of concept demonstrator machines.

n.b. I do have serious issues with the philosophical and technological path that OSE design methodology, and concepts, have taken over the years. Although I do think their hearts are in the right place.  But this is also a discussion for another place & time.

Being an almost 2m, 100kg, I’m indeed well aware not all furniture/fitness equipment is created equal. I’d be able to tell you in 10 seconds flat (pun intended) if the beams would be safe.
That’s probably also why I always build things to be overly sturdy and why I like the grid beams. Always room for (self)improvement.

Product Liability could be another subject, but in this case I would like to borrow it. Creating and selling modular beams with which you _could _build a safe product is different from creating and selling a product that should be safe.

Lego probably also had a deadcount before they came up with Duplo…

With grid beams, the flimsy slides could be strenghtened to support even me.
Would you like to know more?
<end of commercial break 😉 >

If the teenager’s bed collapses – who would be deemed liable in the subsequent court case?  😉

Furniture can be lethal, if badly designed. But plasics (exact polymer not stated) are used for some child-related structures – although these examples are not under constant load, and the stresses are supposedly kept low by telling parents the maximum age/weight of any child using it.

But product liability is probably a separate topic…


Next thing you are going to be telling me not use dominoes for city planning 🙂


Point taken, but building a teenagers bed is quite something else than building a load bearing structure.
It’s a balancing act, in which strenght should indeed alway overpower ‘potential stress’, and even then always design a ‘graceful fail’.

Isn’t ther a ‘golden ratio’ rule somewhere regarding base, height and relative weight that could fix this?

I think the Grid beams actually try to offset ‘overkill of used material’ against ‘throw away economicaly used material’ in time, in favour of the strenght (overkill) of the design.
I for one would love to be able to reconfigure my Ikea lifstyle anytime I see fit, without limitation. Unfortunately their modular designs isn’t even compatible within the same product range most of the time.

It would be quite feasible to use a metal hole template (jig) when drilling through the plastic – in order to get the right spacing.  In fact, this is the way people accurately space manually drilled rivet holes in sheet metal work (even on aircraft structures).

However, to ensure the holes remain square to the beam (and for safety), it would still be best to use a pillar drill, and something to securely clamp the beam and template.

I do like the modular beam approach, as it allows you to quickly improvise structures, and reconfigure as you go.  And of course, it isn’t unique – apart from Meccano there have been “grown up” versions such as Dexion.  (I remember when working in a nuclear lab, over 30 years ago, there was a lot of stainless steel Dexion used to build all kinds of structures for experiments).

As with Meccano, modular structures that have finshed their useful purpose can be canibalized – and the elements reused (again and again) without having to spend time drilling fresh holes in reclaimed beams.

There are some downsides of the modular beam approach, however.
– Structures can not be optimised for strength, weight, and compactness. Your structure may do the job, but it will be bulky and overly heavy for the loads involved. But that isn’t a problem if the structure is only meant to be temporary, to (say) demonstrate a concept.
– It also makes it easy for you to get carried away, ignoring the need for stress analysis, by allowing you to quickly build structures that are actually unsound.

– With regards to making beams out of some kind of extruded plastic (HDPE?) one major problem is that the material itself is not suited to large static structural loads.  HDPE suffers from creep so it shouldn’t be relied upon for building stuff, unless the expected stresses are very small.


Really cool subject.

I also found the Ken Isaac book in pdf: How To Build Your Own Living Structures


Also Please link this topic to the V4 Product Design – Furniture topic!


I think the idea of ‘live size’ mecano is really cool and I really don’t think it’s going to be hard to come up with a simple extention tool to be able to drill the holes DIY.
But before I start designing, I wonder if a ‘drill as you go’ solution might not be a better starting point.
Just drilling the holes you need, might sound a lot like, ‘yeah, like we do right now’, but the holes would still be ‘standards’ based, and so would the material.

For this you might only need 1 solid metal beam Grid Beam, to use as a drilling mould, ‘fixed’ into place using starter holes (which might need a second tool).
Am I crazy, or could this work?


P.S. yes, I know they also talk about this in the video, but as it seems their experimental production setup failed (drilling all holes), I am asking if taking a step back in (DIY) production might still be the answer…

bump :slight_smile:

Some more examples

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