Assembly Line · Documentation
How to mate parts
Mates are constraints between two faces on different parts. They position components relative to each other—like SolidWorks mates—and are saved with your assembly automatically.
Before you start
- Open Assembly Line and select a project.
- Have at least two parts in the assembly (from DXF/SVG import or the project parts library).
- Turn off Exploded View while mating—constraints are not applied in exploded mode.
Step-by-step: add a mate
-
1
Click Mate on the ribbon
The Mate tool is in the Components group (top toolbar). Mate mode turns on and the right panel shows Mate Setup. A status banner appears at the top of the 3D view.
-
2
Pick the first face
Click a flat face on Part 1 in the viewport. The banner updates to show which part you selected. Use orbit (left-drag) to see faces clearly.
-
3
Pick the second face on a different part
Click a face on Part 2. You cannot mate a part to itself—the app will warn you if you click the same component twice.
-
4
Choose a mate type
In the right panel, click one of the mate cards (Coincident, Concentric, Parallel, Perpendicular, or Distance). For Distance, enter the offset in millimeters.
-
5
Click Apply Mate
The second part moves to satisfy the constraint. The mate appears under the Mates folder in the left FeatureManager tree. Changes auto-save to the cloud.
Mate types
| Type | What it does | Typical use |
|---|---|---|
| Coincident | Aligns two faces so they touch; normals oppose (faces flush). | Panels edge-to-edge, lids on boxes. |
| Concentric | Aligns face normals and centers points on the same axis. | Shafts, holes, round features. |
| Parallel | Makes both face normals parallel (same direction). | Parallel plates, aligned sides. |
| Perpendicular | Makes faces 90° to each other. | Corners, brackets at right angles. |
| Distance | Like coincident but keeps a fixed gap (offset in mm). | Spacers, air gaps, standoffs. |
After the mate is applied
- Move / Rotate — Use the Move/Rotate tool on a mated part; constraints re-apply when you finish dragging (unless exploded view is on).
- View mates — Expand the green Mates section in the left tree. Each row shows the type and the two part names.
- Inspect a mate — Click a mate in the tree. The right panel shows type, parts, and offset (for distance mates).
- Delete a mate — Select it in the tree, then click Delete Mate in the properties panel, or right-click the mate in the tree and choose delete.
- Cancel while picking — Press Esc or click Cancel in the mate panel.
Tips & troubleshooting
- Face won’t select
- Zoom in and click directly on a flat extruded face—not empty space. Make sure Mate mode is active (you clicked the Mate ribbon button).
- Part jumps unexpectedly
- The solver moves Part 2 when you apply the mate. Position Part 1 roughly first, then mate Part 2 to it. Add mates one at a time for complex builds.
- Mates seem ignored
- Turn off Exploded View. Constraints are disabled while the assembly is exploded.
- Saving
- Mates are stored inside the assembly JSON and auto-save with the project. Reloading the browser reopens your last assembly with all mates intact.
- Part looks too big / wrong size
- The label (3 mm) in the tree is sheet thickness, not the overall width of the part. Select the part and check Footprint (W×D) in the PropertyManager. If the flat size is wrong, re-import the DXF with DXF units set to mm or inches, or lower XY scale (e.g. 0.1 if it looks 10× too large).
Ready to try it?
Open Assembly Line, add two parts from your project library or import DXF, then use the Mate tool.