Clickfinity: bins that snap into place

You design a Gridfinity bin, print it, and it drops into its baseplate with that soft, satisfying seat. Everything works — right up until you want to hang the organiser on the workshop wall or tilt it onto a trolley. That is when the physics holding the bin down disappears. Gridfinity trusts gravity, and gravity only pulls one way: down. Turn the panel ninety degrees and your bins hit the floor. Clickfinity exists to solve precisely this problem: instead of letting gravity do the work, it hooks the bin to the baseplate with an elastic click that also resists a vertical pull. That click, however, is not free for anyone printing in FDM, and it is worth understanding why before you decide you want it.

From dropping in to hooking on

The Gridfinity interface is deliberately passive. The foot of the bin carries a chamfered profile that self-centres as it lowers into the matching pocket in the baseplate; once seated, the only thing keeping it there is its own weight plus the friction of the chamfers. It is a gravity fit: elegant, forgiving of imprecision, with nothing to fatigue — but resting on one implicit condition: that the baseplate stays horizontal, or nearly so. Tilt it far enough and the chamfer, which only knows how to push the bin up and out, lets it escape.

Clickfinity keeps that locating foot but adds an element Gridfinity does not have: an elastic tab or relief that flexes as the bin lowers, jumps over a retaining lip on the baseplate, and springs back with a click. From that point on the bin no longer comes out by pulling up: you have to overcome the retention first. It is the difference between resting a lid on a box and buttoning it down — you have gone from a gravity fit to a positive catch, and that catch is what makes it viable to mount the system upright or tilted.

The dimensions: the grid stays, the click does not

What makes Clickfinity useful is that it does not reinvent Gridfinity's metrics, only its retention. The grid pitch is still 42 mm, the footprint of each unit sits slightly under that to leave the locating gap, and height grows in multiples of 7 mm. Keeping those figures is what lets a Clickfinity bin and a Gridfinity baseplate — or the other way round — share a grid. The geometry of the click is the only genuinely new part, and it is also the only one without an established canonical dimension.

The click is a cantilever snap-fit: orient it well

An elastic click is, mechanically, a cantilever arm that flexes to let the retaining barb pass and then springs back to shape. Its stiffness — how hard it is to open and how much it retains — depends on the arm thickness cubed: shave 20 % off it and it becomes almost half as stiff. But in FDM there is a second variable that matters as much as the geometry: layer orientation.

Flexing that arm puts one of its faces in tension. If you print the tab so that this tension falls perpendicular to the layer lines, you are asking the bond between beads to carry the load it is least able to bear: layer adhesion is the material's weak direction, and the arm will delaminate within a few click cycles — sometimes on the first. Orient the part so the arm flexes in the plane of the layers, with the fibres running along the cantilever, and the same arm survives hundreds of insertions. This is exactly the problem Print-friendly snap fits works through: in a printed snap-fit, layer orientation is not a finishing detail — it decides whether the part lives or breaks.

First-layer squish adds its own skew. If the barb or lip lands against the bed, those first layers come out widened by elephant's foot, and the click grabs harder than you drew; if they bridge an overhang, they lose definition and can sag. Often, too, the barb simply has to sit near the bed and no orientation avoids it — so plan for it: turn on the slicer's elephant's-foot compensation to trim that widening, or draw a small chamfer at the base of the barb to absorb the excess material of the first layers. And measure the click on the printed part, not just in CAD: elephant's foot shifts the fit dimension by a few tenths you never see on screen.

The three dimensions of the click: overlap, angles and slide

A well-designed click has not one dimension but three, and confusing them is the shortest path to a bin that will not hold or an arm snapped on the first assembly.

The first is the overlap (engagement): how far the barb sits over the retaining lip. It is the equivalent of the interference in a press fit — what actually holds — and in FDM it suffers the same skew Choosing the fit: clearance, transition, interference describes: female reliefs shrink and male features grow, so the real overlap comes out larger than nominal. Draw an overlap sized for metal and in plastic you get a barb that will not pass, or that bursts the arm as you force it. As a matter of geometry, an overlap of a few tenths of a millimetre — not microns — is what gives firm, repeatable retention; the exact figure is set by the variant, and it is worth validating with a coupon before you print a dozen bins.

The second is the two barb angles, and they are what split the effort between going in and coming out. The front face — the lead-in ramp — governs how hard it is to button up: the shallower it is, the more gently the click enters. The back face — the retention angle — governs how hard it is to release: a shallow back angle gives a click you release by hand, one near 90° gives an almost permanent catch you have to force open. Here is the most common mistake: when the click will not hold, people raise the overlap without touching the back angle. That loads the arm on every assembly without giving you more control; often, steepening the retention angle alone takes the same bin from dropping off on its own to sitting firm.

The third is the sliding clearance on the flanks: the side gap through which the bin lowers and rises guided by the foot, separate from the retention. Here you want the opposite of the overlap: a fit that slides without seizing. A clearance of 0.10–0.15 mm per side in PLA gives a seat that enters smoothly without rattling; leave it at zero and FDM's bias turns it into interference, and the bin goes in with a mallet.

Material and environment: what survives the cycles

All the geometry above counts for nothing if you pick the wrong material, because the click's arm is the first part to tire out. A cantilever you button and unbutton daily flexes on every cycle, and PLA is the worst of the common FDM plastics for that job: it is stiff but brittle; it deforms little before breaking — 2–6 % elongation at break — and delaminates within a few cycles. For a click that gets cycled, print in a tougher material: PETG, ABS/ASA, nylon (PA) or PP flex hundreds of times without snapping where PLA gives out on the first handful. Save PLA for the click you mount once and leave in place.

But "leaving it in place" does not make it last forever, and here Clickfinity has a trap peculiar to its use case. A barb holding a loaded bin against the wall is under constant tension, and PLA flows slowly under sustained load (creep): the retention overlap relaxes over weeks even if you never touch the bin again. Permanent mounting does not remove the click's ageing; it only swaps cyclic fatigue for creep under load. The same tougher materials also resist that creep better.

And the environment finishes what the material starts. Clickfinity lives exposed — wall panels, trolleys, systems that get carried around — and PLA softens early: its glass transition temperature sits around 55–60 °C. A sunlit wall, a hot workshop or garage, or the inside of a car in summer is enough to soften the arm, accelerate the creep, and eventually let the bin drop.

Clickfinity or Gridfinity: choosing between them

The positive catch is not free. A click demands more plastic — arms, lips, a more elaborate foot — and more print time. Above all, it introduces an element that ages: every insertion flexes the arm, and no printed cantilever survives infinite cycles; in upright mounting, the sustained load relaxes it even when you never touch it. A bin you button and unbutton daily will tire out by fatigue; one you mount and leave hanging, by creep. The click always pays a price; only the kind of price changes.

So the decision comes down to use. If your organiser is going to lie flat on a table or in a drawer, Gridfinity's gravity fit is more than enough: less plastic, nothing to fatigue, generous tolerance. Save Clickfinity for when gravity is not on your side — wall panels, tilted surfaces, systems that get carried or tipped over — accepting the heavier part and the wear of the click in return. If in doubt, start with Gridfinity and move to Clickfinity only when a bin falls on you; the problem itself will tell you when you need it, and everything you learn sizing that first click carries over to Gridfinity: the 42 mm grid built to fit, because the grid underneath is the same.