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Work in progress.

This is just the living specification documentation for my openGrid bins concept. I attached my first test file of 2x4 h50 bin as STL, since Maker World seem to require at least one 3D model file. When I get to modeling other sizes of boxes, I'll likely upload them separately. Please contact me if you can create some kind of generator / website for creating these, I really would not like to manually model all different sizes.

OpenGrid Bins

The idea for openGrid bins comes from blatantly ripping of Gridfinity (by Zack Freedman at Voidstar labs) and instead utilizing the grid system of openGrid (by David D at 2D3D). I personally like openGrid a bit more, since it gives positive locking into the base grid. I feel like there's a possibility for system which could utilize full-depth openGrid system for walls and undermount, and openGrid lite system for overmount. For this overmount use-case generic bin system would be useful, for the same reasons that made gridfinity so popular.

Original source for openGrid is here: [https://makerworld.com/en/models/1179191-opengrid-wall-desk-mounting-framework-ecosystem](https://makerworld.com/en/models/1179191-opengrid-wall-desk-mounting-framework-ecosystem)

Grid and spacing

OpenGrid uses 28mm grid system. This is the basis for these Bins as well. The lite version of openGrid grid should be used, but nothing here strictly requires that in the mechanical sense. Smallest possible bin would be 1x1, being just under 28mm wide and long. Height is left unspecified, but I'd suggest steps of 10mm.

Separate bins and feet

My aim is to design an system where the bins and their feet are printed separately. First iterations are going to use cross for aligment and superglue for attachment, but I'm totally open for snapping / locking printable options as well. Let me know.

There are couple reasons for this:

• Printing the feet as integral part of the bin makes the bin quite bit higher and thus slower to print.
• The feet have intricate details, making the first layer much more likely to fail.
• If we'd like to skip some feet, either support material or long bridging would be needed.
• And we'd like to skip some feet due the snapping action. 5x5 box with every grid square populated with snapping feet is going to be pain to remove.

Which means that printing feet separately from the bins we gain:

• Easier printing of bins: much simpler first layer.
• Faster printing of bins.
• Selectable gripping power: are all feet locations populated? do all feet locations have feet with snaps?

Bins with width of 1 should likely have 2 feet, bins with wider form should likely have 4 feet.

This of course means that there needs to be some standard for the feet-bin interface. Ideas welcome.

About naming

In the name for these bins, both on websites and in the file name, atleast the bin size should be mentioned.

Width and length should be mentioned by {A}x{B} notation. Where A = width = left/right, and B = length = towards/away.

Height should be mentioned by h{mm} as millimeters. General bin heights are likely something like 30mm or 50mm.

Example from the attached 3D model: ogbin_2x4_h50.stl.

Dimensions

Attached are couple drawings with dimensions. These try to list only the dimensions “relevant to the spec”, since box internals and height especially are going to be dependant on the use-case of that specific bin.

bins-external-dimensions.png

This image shows how bins relate to the underlying openGrid grid. Outside dimensions are nominal 28mm per unit size, with 0.25mm gap left on each side. This means that real external dimensions for 1x1 bin would be 27.5mm x 27.5mm. For 3x4 bin it would be 83.5mm x 111.5mm.

In each outside corner 3mm chamfer is used. This is mostly aesthetic choice, to fit in to the openGrid system.

bins-cross-section.png

This image shows the cross section of unspecified bin with feet, where the feet is expected to be glued without any locating features. In real uses cases there is need for some kind of locating / snapping / locking feature between the feet and the bins. The feet shown is standard openGrid snap.

As shown, the bins sit on top of the standard feet (snap). This makes the bins closely rest on top of the grid as well, which means that the bins are supported even when some feet are missing.

The height of bin is the external height of the bin without the feet. H50 bin would exactly span 50 millimeters upwards on top of the grid.

From the top of the bin and 4 millimeters down is reserved area. This space is to be occupied by relieved walls (as shown in the picture) or by shape which allows snapping feet to grab. The relieved walls are 0.75mm thick to give enough space for the standard snaps to move freely. This is likely nice behaviour when some kind of easily removable lids, which still can be snapped in place to some table-top grid for example.

That reserved area is to allow stacking of bins and lids on top of bins. Lids do not need this reserved area, since they're likely anyway going to have high objects on top.

Corner detail

Corners of the bins are the main locating and supporting features for lids or bins stacked on top. Basic openGrid snaps are only supported by the corners. The bin/lid itself will stand on the walls of bins below but the walls are likely going to be somewhat narrow.

This section is work in progress.