Snap fit
A lid that clicks onto its case without screws: springy arms with a hook at the tip, and the groove they click into in the other part.
- Snap fit AdvancedPart Studio toolbar
| SchoolCAD | Onshape | Fusion | SOLIDWORKS |
|---|---|---|---|
| Snap fit | – | Snap Fit | Snap Hook Snap Hook Groove |
A snap fit holds a lid on without screws. A springy arm stands up from one part with a hook at its tip. As the parts go together, the hook's slope pushes the arm aside; then the hook's flat side clicks in under the edge of a groove in the other part. It works like Snap Hook and Snap Hook Groove in SOLIDWORKS and Snap Fit in Fusion.
Snap fit is in the Advanced tool set. In Standard, find it with Search tools (` or Alt+C), or switch to Advanced at the end of the toolbar.
How to use it#
- Model the case as one closed box, Shell it (tick Hollow) and Split it into a base and a lid.
- Start a sketch on the plane where the two parts meet, and put a Point where each hook goes, just inside a wall: the arm's thickness and a little gap away from it.
- Click Snap fit (in the Boss ▾ menu on the toolbar, with the other fastening features). SchoolCAD grows each hook from the part on the other side of the sketch (the lid), and cuts the groove in the part they meet (the base).
- Each hook turns to face the nearest wall of the groove part for you. Check the sizes, and click ✓.
Options#
| Option | What it does |
|---|---|
| Sketch points | The sketch with the points. Each point gets a hook. |
| End type | Blind: the arm is as long as the Height, from the part's surface. Up to sketch plane: the arm reaches the sketch. ⇅ (Opposite direction) grows it the other way. |
| Rotation type | Aligned to the groove part: each hook faces the nearest wall of the groove part, so hooks on opposite walls all catch. Uniform: every hook faces the Rotation angle, in degrees from the sketch's across direction. |
| Height, Width, Thickness (Body data) | The arm's length, how wide it is, and how thick. A longer, thinner arm bends more easily. |
| Overhang, Lip height (Hook data) | How far the hook sticks out, and how tall it is. Its flat side catches; its slope leads it in. |
| Groove part | The part the groove is cut in, where the hooks reach it. No groove makes the hooks only (to catch on a ledge you model yourself). |
| Clearance | The extra room all round the hook in its groove. |
| Merge scope | The parts that get the hooks. With Merge with all, each hook joins the part under its point (never the groove part). |
Tips#
- For 3D printing, print the arm standing up (along the layers it would snap), about 1.5 to 2 mm thick, and keep the overhang about 1 mm. PLA is stiff: make the arm long. PETG and nylon bend more.
- Put hooks on opposite sides so the lid is held evenly; two or four is usual.
- Add a Lip/Groove so the lid lines up before the hooks click in.
If it does not work#
- A snap hook grows from a part. Put the point on the face it grows from, or on a plane with the part beyond it. Click ⇅ if it grows the wrong way.
- The hooks do not reach the groove part. Move the points closer to the wall (the arm's thickness and a little gap from it), or choose Aligned to the groove part.
- Make the snap hook taller than its lip. The arm must be longer than the hook.