Print-in-place hinge, customizable: screw holes and a stop at each end

A hinge you print in one piece and screw on: two 40 mm leaves, five interleaved knuckles on a 10 mm barrel and two countersunk holes per leaf for M3 or M4 screws. It swings 180 degrees and stops at both ends: the leaves meet face to face when folded, and a tongue under one leaf keeps it from bending back past flat. Set the length (30 to 80 mm), the leaf width, the knuckle diameter and the clearance.

Customize Change it with AIFree STL, 3MF and STEP, no accountMeasured on the model

Parameters

Countersunk screw size

Hinge lengthmm

Leaf width (from hinge axis)mm

Knuckle diametermm

Clearance (moving gaps)mm

Sliders and downloads are free. Changes by the AI designer use credits like any design; new accounts start with free ones.

It prints flat with the leaves on the bed and needs no supports. The knuckles have 0.4 mm of clearance at the default, and the tongue at the flat stop has 0.3 mm, the tightest gap in the part. Both are measured on the model below, but how much gap a hinge needs depends on your printer, so print one first and raise the clearance if it fuses. Strength was not tested.

Parameters

Every slider in the viewer above, with the range the model accepts. The model rebuilds valid at both ends of each range.

Parameter	Range	Default	What it changes
Hinge length	30 to 80 mm	40 mm	Length of the hinge along its axis. There are always 5 knuckles, so a longer hinge gets longer knuckles.
Leaf width (from hinge axis)	24 to 50 mm	25 mm	Width of each leaf from the hinge axis to its edge (the open hinge is twice this). Wider leaves move the screw holes outward.
Knuckle diameter	8 to 12 mm	10 mm	Diameter of the barrel. The leaves are just under half this thick, so a bigger barrel also gives thicker leaves.
Clearance (moving gaps)	0.25 to 0.6 mm	0.4 mm	Gap around the moving knuckles. Raise it if the hinge fuses on your printer, lower it if it wobbles. The gap at the flat stop follows it (0.6 x clearance, never under 0.3 mm).
Countersunk screw size	M3, M4	M3	Countersunk screw size: M3 (3.4 mm hole, 6.4 mm head) or M4 (4.5 mm hole, 8.4 mm head).

Proof: measured on the model

What the design must satisfy and what our CAD engine measured on the model at the default values. Only measured values are shown here; nothing on this page has been printed by us yet.

Requirement	Wanted	Measured
Hinge length	40 mm	40 mm
Width across both leaves, open flat	50 mm (2 x 25 mm)	50 mm
Gap around the knuckles	0.4 mm (the clearance slider)	0.4 mm
Smallest gap between the leaves: the flat-stop tongue in its slot	0.3 mm	0.3 mm
Countersunk screw holes, 3.4 mm for M3	4 holes (2 per leaf)	4
Countersink diameter at the leaf face	6.4 mm (M3 head)	6.38 mm

base: valid solid, one body, 40 x 35 x 10 mm, fits a 256 x 256 x 256 mm printer; overhangs: 1.0% of surface would need support.
lid: valid solid, one body, 40 x 30 x 10 mm, fits a 256 x 256 x 256 mm printer; overhangs: 2.9% of surface would need support.
Motion: 1 moving joint swept through its range with every pose checked for collisions, no problem reported at the defaults. See the Joints tab in the viewer.

Print notes

Orientation: Flat in one piece with the leaves down on the bed, as modelled: the knuckles print in place around each other.
Supports: None
Material: PLA or PETG
Layer height: 0.16 mm
Hardware: 4 x M3 countersunk screws (or M4 with the M4 setting)
Time and filament: About 25 min and 9 g at the default size: a rough estimate from the model's volume and surface (PLA, 15% infill, about 1 mm of walls, 0.2 mm layers), not a slicer.

Print one hinge at the default 0.4 mm clearance first. If the knuckles fuse, raise Clearance to 0.5 or 0.6 mm; the stops were checked at both ends of the slider.
The roof of the slot over the flat-stop tongue prints only 0.3 mm above it. Use a clean first layer, and flex the hinge gently through its full swing after printing to free it.
The countersinks are on the faces that meet when the hinge folds, so the screw heads sit flush between the leaves.

How it was designed

Designed with buildcad's AI agent, checked by the buildcad team. This is the request it started from and an edited account of what it did (more on how text to CAD works).

The request
A print-in-place hinge, two leaves 40 mm long with countersunk screw holes, that prints flat in one piece and swings 180 degrees from flat to folded, with a physical stop at each end. Clearance adjustable.

1
It wrote the checks first
The agent listed a 40 mm length, a 0.4 mm gap between the leaves, no overlap and two 3.4 mm countersunk M3 holes per leaf. For the stops it relied on the motion check, which swings the hinge from 0 to 180 degrees and reports what stops it at each end.
2
First build: the tongue hit the knuckles
After a quick fix to how the folded pose was named, the hinge built, but the new flat-stop tongue on the middle knuckle overlapped the other leaf's knuckles by 8.4 mm3. The leaves collided in all 73 poses of the swing.
3
It sized the tongue to the gap
The agent printed where each knuckle starts and ends (the other leaf's knuckles begin 4.24 mm either side of the centre) and made the tongue narrower than that gap, with clearance on both sides. The swing then came out clean, and the leaves met within 3 degrees of flat and of folded: a physical stop at each end.
4
One slider end lost the flat stop
The slider sweep found that at 0.6 mm clearance nothing touched at the flat end any more. The agent set the gap above the tongue to 0.6 x the clearance, never under 0.3 mm, and all 8 slider extremes then kept both stops with no collisions.
5
What it left to the maker
Its reply says the hinge was not printed: clearance is the setting most likely to need a change on your printer, and the slot roof over the tongue needs a clean first layer and a fine layer height.

One run of the agent: 5 min 5 s, about $0.64 of model time at list price (claude-sonnet-5-5). The model code behind this page is the code it wrote, unchanged.

Change it with AI

Set the sliders, then press Change it with AI: a copy goes to your designs at those sizes and the designer opens with a suggested change you can edit. Its changes use credits like any design; new accounts start with free ones.

Change it with AI Describe your own part Use it from your own AI (MCP)