Tutorial 4: Print-in-Place Hinge

Goal#

Design a hinge that comes off the printer already assembled and working. Two leaves, each 28 mm wide (measured from the axis) and 30.8 mm long along the axis, share a 5 mm pin axis. Three knuckles (two on leaf A, one on leaf B) interleave along the axis. The pin is fused to the two end knuckles of leaf A, so leaf B is held between them, and every moving surface has a 0.3 mm gap so that layers do not fuse. The hinge swings through 180 degrees.

Print-in-place designs are an exercise in disciplined tolerance. The geometry itself is simple; the skill lies in choosing clearances, avoiding overhangs that need supports, and verifying the gap before you print. You will build the hinge fully parametric so that you can retune the clearance after a test print.

What you'll learn#

• Splitting a design into two components that move relative to each other while staying one printed object.
• Parameterizing clearance and pin size.
• Revolve to make the pin.
• Cutting clearance gaps with offset start planes and Cut extrudes.
• Making a Revolute joint with limits and using Contact Sets to test collision.
• Running Interference and Section Analysis to confirm gaps.

Prerequisites#

• Tutorials 1 to 3, especially components and joints.
• Printer capable of 0.2 mm layers with good bridging. Calibrate before using clearances this tight.

Parameters#

Create these in Modify > Change Parameters.

The total length along the axis is three knuckles plus two axial gaps: 3 x 10 + 2 x 0.4 = 30.8 mm. This is why leaf_l is defined as 3*kn_len + 2*ax_gap.

Layout#

The hinge axis runs along X. Knuckle 1 (leaf A) occupies X from 0 to 10, gap, knuckle 2 (leaf B) from 10.4 to 20.4, gap, knuckle 3 (leaf A) from 20.8 to 30.8. Leaf A attaches to knuckles 1 and 3, leaf B to knuckle 2. The pin joins leaf A in one of the end knuckles, as a fixed part, and runs through leaf B's knuckle with clearance.

Because the pin is part of leaf A, only one pair of surfaces rotates against each other: leaf B's bore around leaf A's pin. That makes the clearance the single critical dimension.

Steps#

Part A: Leaf A#

1. New design, save as Hinge. Add the parameters. Set units to mm.
2. Component. Right-click the root > New Component > name Leaf A.
3. Knuckle profile. Create a sketch on the YZ plane. Draw a circle at the origin with diameter kn_od. This is the end view of the knuckles.
4. Leaf profile. On the same sketch, draw a rectangle: from the circle's tangent, extending in the +Y direction by leaf_w, thickness leaf_t, with its top edge aligned with the circle's top tangent so the leaf's surface is flush with the knuckle top (so the hinge lies flat when open at 180 degrees). Use Constrain > Tangent for the line to the circle, or add a horizontal line from the circle top.
5. Trim. Trim the circle portion inside the rectangle so that you have one closed profile with a rounded end. Use Trim (T).
6. Extrude knuckle 1. Press E, select the profile, set Direction to One Side, distance kn_len (10 mm) along +X, Operation New Body. Rename it A_knuckle1_leaf.
7. Extrude knuckle 3 plus leaf. Start another Extrude, same profile, with Start set to Offset of kn_len + ax_gap + kn_len + ax_gap = 20.8 mm, distance 10 mm. Operation Join to the same body would not connect (they are far apart), so make this New Body, then bridge them later with the leaf.
8. Leaf link. The leaf portion of the profile in knuckles 1 and 3 is a stub; join them with the leaf plate: sketch on the leaf top face a rectangle that spans X from 0 to 30.8 mm and the same width. Extrude it leaf_t downward and Join it. This forms leaf A as a single body with knuckles at the ends.
9. Gap in leaf A for knuckle 2. The plate must not run through the middle of leaf B's knuckle area. Cut a notch: in the middle region (X from 10 to 20.8, the knuckle 2 span plus the two axial gaps) cut the leaf plate back from the axis to kn_od/2 + 1.5 mm (7.5 mm). Use a rectangle cut with a Y range from the axis to 7.5 mm. Leaf A must clear leaf B when closed at 0 degrees and open at 180 degrees (see Part E).
10. Pin. Create a sketch on the XY plane (the axis lies in it at Z = 0). Draw the revolve profile of the pin above the X axis: a rectangle from X = 0 to X = 30.8 with radius pin_d/2 (2.5 mm), one edge on the X axis. No retaining heads are needed: both ends of the pin are buried in the end knuckles of leaf A, and the 0.4 mm axial gaps keep leaf B between them.
11. Revolve. Choose Create > Revolve (it has no default shortcut in Autodesk's list; R is the 2-Point Rectangle), select the profile, axis = the X axis line, Operation Join into leaf A. The pin fuses with the end knuckles of leaf A.

Part B: Bore clearances#

12. No bore in the end knuckles. The pin is part of leaf A, so the end knuckles are one solid with the pin and need no bore. The bore belongs to the middle knuckle in leaf B, covered in Part C.
13. Check leaf A. Leaf A should now be one body: two end knuckles joined by the plate, with the pin through the middle.

Part C: Leaf B#

14. New component Leaf B. Activate it.
15. Knuckle 2 profile. Sketch on the YZ plane: circle diameter kn_od at the origin, plus leaf plate going in the -Y direction (opposite leaf A) with the same thickness and flush tops/bottoms as appropriate. A flat 180 degree hinge needs the leaves to lie in one plane when open; place leaf B's plate flush with the same surface as leaf A's.
16. Extrude. Start at X = 10.4 mm (kn_len + ax_gap), distance kn_len, New Body. Leaf B is only as long as its knuckle (10 mm), shorter than leaf A.
17. Bore. Create a sketch on the end face of leaf B's knuckle: circle diameter hole_d (5.6 mm) at the axis. Extrude Cut through the knuckle (distance kn_len). The bore leaves a 0.3 mm radial gap around the 5 mm pin.

Part D: Clearances between the end faces#

18. Axial gap. Because you positioned knuckle 2 with Start offsets that include ax_gap, the end faces are 0.4 mm apart. Verify with Inspect > Measure between the two faces (0.4 mm).
19. Check that no body overlaps. Use Inspect > Interference with Leaf A and Leaf B selected. It must report no interference.
20. Cone pads. To improve printing, replace flat gaps by 45 degree chamfers on the facing knuckle edges: apply Chamfer (Modify > Chamfer) 0.8 mm to the outer edges of the facing faces. These avoid elephant-foot fusing where the first layer squishes out.

Part E: Opening angle#

21. Why 180 degrees works. As modeled, both plates are flush with the knuckle tops, so the leaves lie in one plane (flat). Closing the hinge swings Leaf B 180 degrees about the axis. Check by rotating Leaf B about the axis by 180 degrees in a temporary Move (M, Rotate), then run Interference. The notch from step 9 is what avoids a collision with Leaf A's plate in between. If a collision appears, enlarge the notch or taper the leaf edge with a 30 degree chamfer.
22. Undo the test move (Ctrl+Z) or drag the timeline marker back.

Part F: Joint and limits#

23. Revolute joint. Press J. Component 1: select the pin axis on Leaf A (snap to the circular edge at the pin end). Component 2: the circular bore edge on Leaf B. If the joint origins end up on opposite sides, use Offset X to align along the axis. In the Motion tab choose Revolute with the Rotation Axis along X.
24. Limits. In the joint dialog, open Joint Motion Limits for the Revolute motion, check Minimum and Maximum and set 0 deg and 180 deg (the joint's zero is the flat pose in which it was created; if Leaf B swings the wrong way, use the Flip option). Use Preview Motion to test it. Click OK.
25. Ground Leaf A. Right-click > Ground. Drag Leaf B to confirm it swings, stops at both ends.
26. Contact Set. Use Assemble > Enable Contact Sets and New Contact Set with the two leaves to see them stop if they would collide.

Part G: Print preparation#

27. Orient. Lay the hinge flat with both leaves on the bed (the open, 180 degree position). The pin axis is then horizontal, parallel to the bed, so the round pin and bore are printed as stacked layers with some stair-stepping; the 0.8 mm chamfers on the facing knuckle edges (step 20) reduce the elephant-foot fusing of the first layer.
28. Slicer settings. Layer height 0.15 mm, no supports, no brim touching the knuckles, 3 walls.
29. Test print. Print a scaled test with only knuckles (20 mm length) first to tune gap.

Checkpoints#

• Radial gap between pin and bore: (5.6 - 5.0) / 2 = 0.3 mm.
• Axial gap: 0.4 mm on each side of the middle knuckle.
• Hinge turns from 0 to 180 degrees without interference.
• The timeline lists, for Leaf A, sketch, three extrudes (two knuckle extrudes and the plate), the notch cut and the revolve; for Leaf B, sketch, extrude and the bore cut; then the chamfers and the Revolute joint.

Gap guidance by printer#

Variations#

1. Living hinge alternative. Replace the pin with a 0.5 mm thick strip in PP or TPU.
2. Five-knuckle hinge for wider doors.
3. Detent. Add a 0.3 mm bump on a knuckle face to click at 90 degrees.
4. Counter-sunk screw holes in the leaves if you later glue a lid.
5. Spring. Use a printed torsion spring from TPU (verify materials).

Troubleshooting#

Related#

• Joints and Joint Limits pages cover every dialog option in Part F.
• Design for Manufacture in the sheet metal and plastic section.
• Tutorial 12 extends tolerance planning to a multi-part assembly.