Assembly Joints
Updated v2.3.8At a glance
- Eight joint types: Fixed, Revolute, Slider, Cylindrical, Ball, Planar, Pin-Slot, Distance
- Pick a reference on each part — the assembly snaps together in a live preview
- Drag any jointed part and it moves only the way its joints allow
- Linked duplicates mirror a source part and follow its edits; Break Link anytime
- Interference check lists every overlapping pair with its true clash volume
- DOF badges show what can still move; redundant and conflicting joints are flagged
Joints turn placed components into a working assembly. Pick a joint type from the Joints toolbar group, click a reference on each of two parts — a face, an edge, a hole rim, a point — and the parts snap together with exactly the motion that joint allows. The whole assembly solves as one system, so mechanisms that loop back on themselves land where the math says they should.
The eight joints
| Joint | Motion it allows |
|---|---|
| Fixed | none — welds two parts together (with an optional offset) |
| Revolute | hinge: one rotation about the shared axis |
| Slider | one straight travel along the axis |
| Cylindrical | rotate and slide on the same axis — a pin in a bore |
| Ball | free pivot about a shared point — a rod end |
| Planar | slide and spin on a shared plane — a part on a table |
| Pin-Slot | spin plus travel along a slot |
| Distance | hold a set distance between two references |
Revolute and cylindrical joints take angle limits, sliders and cylindricals take travel limits, and axis-based joints have a Flip toggle for references that face the wrong way.
Creating a joint
Choose the type first, then the tool walks you through Reference 1 and Reference 2. As soon as both are picked the parts snap together in a live preview — adjust the offset, limits, or Flip and watch the assembly follow. If the new joint would fight the joints you already have, the dialog tells you inline and the assembly stays put; nothing commits until you press OK.
References stick to the geometry they were picked on: rebuild a part — resize the hole, move the boss — and its joints re-derive from the same faces and re-solve.
Knowing what can move
Every component in an assembly carries a badge in the browser: a green check when it's fully constrained, a dof N count while it can still move, and a pin when it's grounded (an assembly always keeps at least one grounded anchor — the first part is pinned automatically). Joints get badges too: redundant (amber) when a joint repeats constraints others already impose — tolerated, not fatal — and conflict (red) when joints genuinely disagree, in which case the parts stay where they are until you fix or delete one.
Driving a mechanism
Right-click a revolute, cylindrical, or slider joint → Drive and type an angle or a travel. The assembly re-solves to that position, clamped by the joint's limits — the quickest way to check a mechanism at both ends of its swing. Joints are always editable from the tree: double-click to reopen the dialog, or suppress one to try the assembly without it.
You can also just grab a jointed part and drag it — it moves only the way its joints allow. A hinged door swings on its hinge, a slider runs on its rail, and the part never comes off its constraints no matter where you pull. Limits hold mid-drag, and each drag is one undo step.
Linked duplicates
Pasting a copied component offers Deep Clone (an independent copy) or Linked Duplicate —
a mirror that follows the original. Edit the source and every linked copy updates instantly;
each copy keeps its own position, grounding, and joints, and shows a linked badge in the
browser. Break Link makes a copy independent whenever you're ready to diverge, and deleting
a source with live copies warns first. Four identical brackets on a frame = model one, link
three.
Interference check
The Interference tool (Inspect group) examines every pair of parts in your assemblies and lists exactly which ones overlap — with the true overlap volume of each clash in your preferred units. Click a result row to light up both offending parts. A fast bounding pass keeps it quick even on busy assemblies.
Measurements keep up with all of it: Quick Measure and 3D dimensions between any two parts stay exact wherever the parts sit — moved, rotated, or jointed.