date: 2019-09-11
title: Gridbeam, gridblock, and gridrack
summary: It's cool to build everything based on odd multiples of a unit block with centered bolt holes

Gridbeam, gridblock, and gridrack - 2019-09-11 - Entry 26 - TOGoS's Project Log

Notes to self

Proposed outline (new as of 2019-09-02)

Where to find pictures

Grid beam is a system of beams in which the width of each beam is equal to the hole spacing.

Some 'Open Source Ecology' wiki page

At some point since my previous project log post I swallowed the gridbeam pill and now everything I make has to be gridbeam-compatible. For boxy things this means dimensions are a multiple of 1½″ (multiples of 4½″ and/or 12″, are desireable for reasons I'll get into shortly, with 18″ being especially handy). For equipment that isn't itself gridbeam but that is to be mounted on gridbeam structures, this means mounting holes accept ¼″ bolts and are in standard positions.

I've accumulated a lot of opinions about bolt holes and box sizes.

But first, pictures.

Making gridbeam in the drivway, using an 8′×1′×4½″ gridblock box as a workbench.
This 12″×4½″ pegboard panel (sprayed with 'stone texture' spraypaint to make it look cool) fits nicely onto the end of my boxes.
18″ cube in which my CNC router lives. Sides have holes on a 4½″ grid, plus a few extra along the diagonals. The handles and shelf supports are just gridbeam or gridrail attached using those holes. The shelf simply rests on the rails, and has built-in LED strips.
A 4′×1′×4½″ OSB box with an 18″ pegboard panel attached. These boxes are super handy when I need a flat work surface or a block to which I can attach other stuff.
An 36″×12″×9″ OSB box shelf originally intended to be attached to a wall but which is currently being used as a stand-alone shelf in the kitchen.
Inside of a 18″×36″×9″ box with inset KV rails holding a shelf with built-in LED strips (I'm all about building LED strips into things, so long as the connectors don't stick out and ruin the boxiness). The hole pattern is some subset of gridbeam holes (3⁄8″) plus some on a 6″ tall × 8″ wide grid (offset vertically by 3⁄4″ from the gridbeam hole grid to avoid interference with it) of larger 'macro TOGRack' holes (7⁄16″ or ½″, for 3⁄8″ bolts) for attaching to studs in the wall (or for running wires through).
Solar charge controller mounted on a 12″ rack. 'Equestrian green' is the official color of gridrack panels.
12″ pieces of 'slotted gridrail', made by gluing together ½″ strips of pallet wood.
When you slap a ½″ board on either side of a square of two-by-fours you get a box that's 4½″ thick. Which works well if you want to have gridbeam holes down the middle of your two-by-four. This shows the underside of a box I made to test out that design. It's being used as a shelf, and the space underneath holds a power supply, wiring, and one of my LED blocks.

Maybe talk about these LED blocks in a different entry because they'd benefit from some animations or interactive buttons or something.

WSITEM-100089: A 9″ 'gridbeam lamp'. This one has 6-pin connectors at either end and a barrel connector on the side (there are 3D printed plugs stuck into them in order to keep polyurethane off the pins). Pinout on the 6-pin connectors is +,G,R,B,W,-, where G,R,B,W can be connected to - to turn on the lights. Since + and - have dedicated pins, the lights can be controlled independently of whether the whole unit as a whole is powered. The idea is that you could power the unit using the barrel connector, but then hook up any RGBW LED controller you want, which draws its own power and controls the lights from a single 6-pin connector.

Regarding spelling of nominal lumber dimensions

I'm trying to follow a convention I picked up, I think from the gridbeam guys, of referring to nominal lumber sizes by spelling out "two-by-two" or "two-by-four", wheras actual [approximate] sizes are referred to with digits, e.g. "A 13½″ cube may be constructed out of two-by-twos".


Before I discovered gridbeam, I had wanted a way to build modular electronic thingamabobs, and so I invented a couple of personal standards for small (3½″) wooden panels on a rack:

While TOGRack works well for its purpose (it's basically a smaller, rounder-numbers version of Eurorack), the utility of macro-TOGRack (which provides a 'widely spaced regular grid of attachment points') is a little less clear. The 16″ grid was chosen because that's the normal distance between studs and floor joists, but since a panel takes up one attachment point, you can only have panels spanning every other space. This works fine if you are just using the mounting holes to attach unistrut, or build panels that are just under 16″ wide and put bolts at the edges or corners (maybe using some big old square washers to hold the panel down), but most panels don't work like that. They have mounting holes inset from the corners that they expect you to put screws through. 19″ racks provide a standard for this kind of thing, but the dimensions are a little bit weird and overly-specialized (for some reason the side-to-side dimensions are specified in millimeters while the vertical dimensions are specified in inches, and the hole spacing is pretty wacky). What I really want is a unifying scheme for everything I build.

Frames and Blocks

This got me theorizing about the difference between what I call 'frame-based' and 'block-based' building systems. In frame-based systems you have a dichotomy between the framing and the stuff between the frames, whereas in a block-based system, everything's a block, and blocks stack. Some examples of frame-based systems:

A characteristic of these systems being that the primary building blocks of these system don't fill a whole 'unit' of space, since there needs to be room for the frame at the edges. Or thought of another way, the connectors between pieces add their own thickness. This causes some trouble when you want to have content that spans multiple cells, because its can't just be a multiple of the single content width. It has to also include the width of the frame parts that its skipping over. If I put two of my 2-wide Minecraft hallways together, the resulting hallway is 5 blocks wide, not 4.

My solar panel / air conditioner shade assembly. The panels are held onto the frame by square nuts tightened down with bolts between the panels. Given the different roles of the panels, the bolts, and the beams, and the fact that it doesn't tesselate at all, I consider this a pretty 'framelike' construction, even though the panels and the unistrut are, by themselves, box-shaped and therefore stackable.

The trouble I have with frame-based systems is that they make it difficult to mix components at different scales. Say you want to create a 4×4-unit panel. The width and height are going to be 4 times the width of a 1-unit panel, plus 3 times the width of the framing. Which is a little bit yucky in itself, but the real problem is structural: this panel is probably going to be somewhat massive, so that the framing intended for 1-unit panels might be insufficient. So now you need to come up with yet another class of part that's neither frame nor panel to support these larger things.

In contrast, in a block-based building system, the content itself is the structure. Lego bricks are a pretty good example (they can even be combined at different scales to some extent), as are the blocks in Minecraft (which I sometimes wish I could subdivide further).

Most structures in real life aren't strictly one or the other. In a brick wall the bricks themselves are carrying the load of everything above them, so in that sense are block-like, but have to be sized taking into account the mortar between the bricks, and are in that way frame-like. You might call this structurally blocklike but dimensionally framelike.

Brickwork. Note the length of the header being less than half the length of the stretcher to make room for the mortar.

Walls in Satisfactory might deserve a mention, if only because I've been playing Satisfactory lately and they're on my mind. In Satisfactory you can place big blocks called "foundations", which are standard dimensions (the large ones are 8×4×4 meters). Building with those is similar to building with blocks in Minecraft. But Satisfactory also gives you walls, which snap to the edges of foundations. I'd be tempted to say that this makes Satisfactory structures framelike, except that as far as foundations and other walls go, walls do not take up their thickness, making Satisfactory's foundation+wall system truly blocklike, but with optional zero-width borders between cells.

From this perspective, both TOGRack and macro-TOGRack both appear to be framelike systems, since their primary use is to attach panels to rails, or to attach rails to walls. There's no obvious single fundamental building block in either system. And maybe framing things that way helps explain why I found those standards less useful than I hoped they would be.


I came across gridbeam while wasting time on Hacker News one day. It seemed like these guys were trying to solve the same problem I was, so I watched some videos, bought the book, and decided to buy into this sytem.

Unlike my panel standards, gridbeam is intended to be used in 3 dimensions. To some extent this helped me resolve the conflict between frame-based and block-based building systems in my mind, as the frames (structures made by bolting together two-by-twos) have dimensions that are a multiple of the unit block size (1.5″). They'll tell you that this is very important because it's what makes tri-joints work. I don't even use tri-joints that much (I'll often construct things using gridbeam-compatible panels instead of actual grid beams); I'm just happy that I don't need to think about 'framelike building systems' anymore (they are still useful, but being themselves based on gridbeam seems to make the remaining variables not matter as much).

My gridbeam is not this nice. I make mine out of two-by-twos from Home Depot, which are relatively crappy pieces of wood and aren't even a full 1½″ thick. They still get the job done, though.


'Gridblock' is what I call blocks thicker than a single two-by-two that are designed to compose (by stacking and/or bolting together) with gridbeam stuff.

The way that panels are conventionally attached to gridbeam structures is that you have a gridbeam structure, and then you attach panels to the sides. That's fine, but it didn't sit quite right with me that after adding a panel, the overall structure is no longer a nice, symmetrical, even-sized block! And gridbeam is not really suitable for smaller boxes anyway, as the two-by-two framing is totally overkill and wastes a lot of space.

My solution is to build what I call 'gridblock boxes'. Their external dimensions are nice gridbeam-compatible sizes (4½″, 6″, 12″, 18″, and so on) and bolt holes are placed following the gridbeam convention so that they can be bolted to each other or to grid beams. Each box is a single, atomic piece, usually held together with wood screws or glue.


These constraints got me thinking: if I want to only drill some of the holes, which ones should get priority? Since edges are often off-limits, it should be at least the first hole in from the edge. For a 12″ box, this would mean holes 2¼″ from the sides in each corner. Two of these boxes could then be connected by matching up the faces and bolting them together.

When you put two same-sized blocks right next to each other, the holes line up and you can attach them, woohoo!

Unfortunately, perfectly matching up the faces is the only way that two 12″ gridblock boxes can be connected. Otherwise you need to drill more holes. This is also a problem when trying to connect boxes of different sizes.

There's no good way to make a subset of the holes in our 12″ boxes line up for offset or scaled cases.

I wanted to be able to scale up gridbeam to make blocks that are larger-than-but-still-compatible-with gridbeam without necessarily exploding the number of bolt holes that would have to be drilled. The trouble is that while each gridbeam unit block has a single bolt hole through the center, when scaled up by an even factor (4 or 8 in the case of 6″ or 12″ blocks), the center of the scaled-up blocks aren't valid bolt hole locations, which means that instead of a single, centered bolt hole, you have to (assuming you're going for symmetry) make 4 bolt holes.

I don't want to have to drill that many holes! It was a pain to even write the SVG to represent them! Not even to mention how many we'd have to drill for 24″ boxes!
And the hole pattern for 6″ boxes is just dumb. All the downsides of being clustered in the center without the benefit of a single central hole.

But if you scale up by an odd factor, like 3, the resulting blocks still have a single canonical center bolt hole. Scaling up the gridbeam unit by 3 gives us the somewhat odd dimension of 4½″, but that divides well enough into 9 and 18, and also happens to be the thickness you end up with if you attach ½″ boards to the edges of a two-by-four (which are 3½″ wide).

Following the blocks-are-multiples-of-3-of-the-base-unit rule, which gives us 4½-inch 'gridblocks', we can go up to an 18″×18″ box and only have to drill 16 holes to be able to accommodate attaching 4½″ or 9″ boxes in the middle or in any corner.

You could take this further and say that the next size up after 4½″ should be 13½″, not 9″ or 18″. The reason I don't build 13½″ boxes is that 13½ is close enough to 12 to make combining with 12″ things (which I expect to be common) awkward. But I also don't expect to be trying to hold such large blocks together with a single ¼″ bolt (for attaching boxes to walls I use a system of 3⁄8″ bolts on a 8″×6″ grid, which is sort of a gridbeam/macro-TOGRack compromise; see the shelf with KV rails for example).

An 18″ box and a couple of 9″ boxes. Keeping holes centered as the box scale is increased means that the holes can remain regularly spaced, leading to more flexibility in attachment positions. The larger, blinking circles show the positions where you might put those macro-TOGRack/gridbeam compromise holes, for mounting to a wall.


So back to the rack situation. Speaking of framelike systems built out of blocklike ones...

I'd been wanting to mount my solar charge controller and related stuff on a rack on the wall in my basement. Originally the plan was to make a 19″ rack and mount them all on that, but in addition to the already-mentioned things that make 19″ panels annoying, the space between the studs where I wanted to put it is only 15″ wide, and it was important to me that I make use of that space rather than have yet another thing sticking out from the wall.

I'd already made a few 12″ gridbeam-mountable square panels for holding power tools (a sander and a router), so it wasn't much of a stretch to declare "12-inch gridrack panels it is". So I made a rack using a pair of what I call "gridrail", which is gridbeam but made of one-by-twos, because it doesn't need the holes in the side-to-side direction. The rack fits between the studs. This convention is easily adjustable to any other multiple of gridbeam widths. For example 9″ could be useful in tighter spaces, and a 'double-width' 24″ rack could hold extra wide stuff (including adapters for 19″ equipment).

12″ gridrack with some different-sized panels attached

So far I've built 3 gridracks (the 12″ one for my solar charge controller and related equipment, and a couple of 9″ ones), not counting the implicit gridracks that pop into existence any time two pieces of gridbeam run parallel to each other. I expect to build more as attach-stuff-to-other-stuff situations continue to arise.

To summarize

Making stuff based on gridbeam is great because: