Gridfinity bin

A storage bin for the open Gridfinity system by Zack Freedman, printed standing on its feet without supports. Choose its size in grid units and height units, how many compartments and rows it holds, label tabs, scoops, and what goes in the base. Switch its fit gauges on and it proves that it seats in a baseplate and stacks on the next bin.

What it shows

• One compartment, patterned. A single rounded pocket is built once (feature.extrude, feature.fillet on its floor with chain, a scoop and a label tab cut from it with feature.boolean), then copied with feature.pattern in two directions. Every compartment gets rounded corners and a rounded floor from those few steps, whatever the count.
• A profile swept round the bin. The stacking lip is one feature.sweep of its section along the bin's closed outline, with the rounded tip in the section as a sketch.path arc, so its faces are exact planes, cylinders, cones and tori.
• Choices that change what is built. table.set with choicesFrom holds the hole styles; when conditions switch the magnet, screw and bridge-layer cuts, the tab, the scoop, and the lip or plain rim; the corners-only style changes a pattern's step and count by formula (feature.pattern).
• Ranges that follow each other. How many compartments fit depends on the bin's width and wall; the tab needs a height of 3 units; the wall's limit depends on the lip; and the rows follow the compartments side by side, so a bin holds at most 48 (variable.publish with formula min and max). A bad combination is refused with the reason.
• Checks against a real fit. One option, Show fit gauges, adds a baseplate socket and the foot of a stacked bin at the bin's two far corners (feature.when), and the assertions that measure against them (assert.add with when) switch on with it: overlap, distance to each 45 degree face, and clearance on the lip. With it off, the file holds just the bin.

A static model of a bin is one bin; this one is every size from 1 x 1 x 2 to 6 x 6 x 15, with up to 48 compartments.

The real thing

The system. Gridfinity is Zack Freedman's open modular storage system (Voidstar Lab, 2022, MIT licence). Every number below that decides whether a bin fits comes from these sources, read as numbers; no code was taken:

• gridfinity-unofficial/specification, its block and baseplate profile drawings: 42 x 42 x 7 mm grid, 41.5 mm bin (0.5 mm clearance), 4.75 mm foot, 5 mm baseplate, 6 x 2 mm magnets, M3 screws. The drawings label the corners "3.75Ø" and "8.0Ø"; the plate's 4 mm radius less the 0.25 mm gap on each side gives 3.75 mm, so 3.75 is a radius, as kennetek's BASE_TOP_RADIUS = 7.5 / 2 also says.
• kennetek/gridfinity-rebuilt-openscad (MIT), src/core/standard.scad and gridfinity-baseplate.scad: the foot profile (0.8 mm chamfer, 1.8 mm straight, 2.15 mm chamfer), the lip (0.7 mm chamfer, 1.8 mm straight, 1.9 mm slope, a 1.2 mm support and a 0.6 mm tip radius), 6.5 x 2.4 mm magnet holes and 3 mm screw holes 8 mm in from the unit's sides, 7 mm base height, 1.2 mm dividers.

Where this Jig decides for itself, and why:

• The wall is at least 1.2 mm (three 0.4 mm lines), not the reference's 0.95 mm, for FDM strength.
• The label tab's support is at 45 degrees, not the reference's 36, so it prints without supports. The tab is sized by what it carries: a flat area 12 mm front to back, room for 12 mm label tape. That holds in the back row too, where the lip overhangs the tab by 1.4 mm at the default wall, so the tab is 14.4 mm deep there and everywhere (the reference's is 15.85). Where the row or the height is short the flat is smaller, and the output Flat label area says how much.
• The screw holes are 5.8 mm deep, not the reference's 7 mm, leaving 1.2 mm of floor above them.
• With both magnets and screws, each hole's ceiling has two thin steps (a slot, then a square, one 0.2 mm layer each), the standard way to bridge a ring without supports.
• The top of the dividers and tabs is 0.6 mm under the wall's top, 0.25 mm below the feet of a bin stacked on this one.

A note on the published geometry. A published plate's ridges between sockets come to a knife edge 5 mm above the socket floor, while the bin's underside between its feet starts at 4.75 mm. Both are published numbers, so on paper a multi-unit bin overlaps the very top 0.25 mm of each ridge, where the ridge is narrower than one printed line and does not print to its tip. The bin rests on the two 45 degree faces of the socket. The gauge here is therefore cut to stand clear of everything else, 0.2 mm above the socket floor and 0.05 mm under the foot's top, so it can only touch on those two faces, and each is proven on its own. This Jig's companion gridfinity-baseplate stops its sockets flat at 4.75 mm, so a bin in that plate has no ridge above its underside at all.

Printing. Standing on its feet, as modelled: the 3MF is in print orientation. PETG (or PLA), 0.4 mm nozzle, 0.2 mm layers, three perimeters. The foot's 0.8 mm bottom chamfer is the first-layer chamfer, and every hole has a 0.4 mm chamfer at the bed. No supports: no sloped face leans further over than 45 degrees. Flat downward faces remain in three places, and they are short bridges: the ceiling of each magnet hole (6.5 mm across), the ceiling of each screw hole (3 mm), and the strip between neighbouring feet (0.5 mm wide, wider only in the small star where four feet meet). The tops of the 1.2 mm dividers stay square: three lines of plastic leave no room for a chamfer. Press or glue in 6 x 2 mm magnets. A 6-unit bin is 251.5 mm long, so check it against your print bed.

The mass and filament length shown are for the model printed solid. PETG density 1.27 g/cm³ is from the Prusament PETG data sheet (ISO 1183); a slicer's infill in the feet and floor will use less.

Parameters

Outputs: outside width and depth, height with the lip, inside depth, each compartment's clear width and depth, the label tab's width and its flat label area in the back row, the magnets needed, and the mass, volume and filament length if printed solid. At the defaults (2 x 3 x 6, six compartments, full-width tabs, scoops, magnets in every unit) the bin is 83.5 x 125.5 mm and 45.55 mm tall, each compartment 39.95 x 40.23 mm clear, 24 magnets, 12 mm of flat label area, and 174 g or 56.8 m of filament as a solid print.

Checks

The assertions, in words: the width and depth are units x 42 mm less 0.5 mm; the bin stands on z = 0 and its top is at units x 7 mm plus the lip's height. The bottom of the first unit's foot has the closed-form area of the published profile less its holes, there is one bottom face per unit, and the feet's side area equals the closed form of the 0.8, 1.8 and 2.15 mm profile in every unit. A section 0.5 mm under the floor is the whole outline, so nothing breaks through it. The straight band of the lip stands the published 1.9 mm in from the outside.

With Show fit gauges on, at the bin's two far corners: the bin does not enter the baseplate socket, the foot's lower and upper 45 degree faces each touch the socket's (each measured on its own: a socket 0.1 mm looser or tighter, or looser on one of the two faces only, fails the assertion for that face), the foot of a stacked bin enters no compartment or tab and rests on the lip.

For printing: facing compartment walls are at least 1.2 mm apart both ways (in a low bin the tab's sloping underside takes the place of the back wall and is measured instead), the side and front walls measure the wall thickness, no flat face leans further than 45 degrees from the bed, the conical corners of the feet and lip are no steeper than 45 degrees, and the only flat downward faces above the bed are the hole ceilings and the web between the feet, at their own heights. The counts: one floor per compartment, one scoop and one tab front per compartment when they are on, and as many magnet and screw holes as the style asks. The label tab's flat area reaches the lip or rim above it, measured on the back row, where it is shortest.

To keep them light on a large bin, the lip band, the first foot, the wall and the divider distances are measured on the first unit, row or column; the others are pattern copies.

tools/jigs.py check runs check-range: 103 points (the defaults, 64 corners of the box of the ranges, every choice and 32 random points from seed 1), all passing, none unproven; the slowest regeneration takes 0.74 s (meta.json). Most corners are not in that sample, so the combinations that should break the Jig were tried by hand with param.set. A label tab on a 2-unit bin, the lip with a 2.4 mm wall, and more than 48 compartments are refused, with the range that applies. These pass with the gauges on: the largest bins the form allows (6 x 6 x 15 with 12 x 4 and 8 x 6 compartments, magnets and screws), 1 x 1 x 2, a 2 x 2 (whose diagonal gauges come closest to each other) and 2 x 1 x 3 with a 2.4 mm wall and no lip. Those largest bins take about 8 s to open, regenerate and finish all 27 assertions on the same machine; the assertions run off the form's thread.

The cone-corner draft is measured on sampled faces of the first unit's foot and its corner of the lip (the others are copies of them), so it is a strong check rather than a proof (F-067 in 3DCraft Examples' feedback list). Wall thickness uses plane-to-plane distances, because measure.thickness finds the wall but cannot prove it on this body (F-020 in the same list).

Not checked: the actual print, the strength of a filled bin, how a magnet holds, or a ridge in a real baseplate.

Export

Choose File > Export..., format 3MF (or STL or STEP). With Show fit gauges off, as it is by default, the file holds just the bin, in print orientation: send it to the slicer and print it on its feet, without supports. Switch the gauges off before exporting if you turned them on: they are bodies of the model, and an export writes them too (see Platform notes).

The README in the model's repository has the rest (Files, Rebuild, Difficulty, Platform notes, Licence): the whole README on GitHub.