Physical-link attachments

Definition#

A Physical-link attachment is a printable attachment instance hosted by one Physical link. Sleeves, clamps, sockets, end caps, tube-mounted brackets, and member-specific mounts belong in this category.

The attachment is not an imported static mesh. It combines:

• a reusable attachment type from the frame's Attachments catalogue;
• a parent Physical link and anchor node;
• authored dimensions, orientation, implementation parameters, and materials;
• implicit values resolved from the parent member.

The reusable type is authored in the separate Attachment Editor. This page describes how an instance behaves inside the Frame Editor.

Parent link and anchor node#

Every Physical-link attachment belongs to one Physical link and names one node on that link as its anchor. The anchor establishes the local start position; the attachment's offset then moves its centre along the member axis.

The complete placement relationship is:

``text parent Physical link + anchor node + direction + offset = attachment placement ``

The anchor may be a terminal node or another valid node on the link. Creation defaults enable end pinning only when the anchor is one of the Physical link's terminals. Moving an existing attachment retains its chosen pinning setting.

Direction, rotation, and offset#

The attachment has a direction along the parent axis and a normal that records its rotation around that axis.

• Flip direction reverses which way the attachment points along the link.
• Rotate attachment changes its roll around that direction when the rotation mode permits local edits. Non-circular stock requires aligned roll; rotate the Physical link instead.
• Offset moves its centre away from the anchor along the current direction.

The Flip direction icon is highlighted when the attachment faces opposite its parent link. Its tooltip reports the current direction.

These operations solve different problems. Flipping is not equivalent to rotating 180 degrees around the axis.

The creation default can orient a new attachment using the nearest terminal or preserve the parent link's direction. New instances request Independent roll. Follow parent preserves their relative angle while permitting edits; Locked to parent preserves it and prevents local edits. A non-circular host requires aligned roll and disables mode and angle changes, while retaining the requested policy.

Offset (°) edits roll about the parent's ordered axis. It is separate from the axial offset distance. Mode changes preserve pose, including a nonzero locked angle. See rotation modes and roll offset for signs, parent navigation, and required locking.

Absolute and relative dimensions#

Length, thickness, and offset can each be authored in one of two modes:

• Absolute: an expression resolved in millimetres.
• Relative: an expression multiplied by the parent profile's reference length: radius for circular stock, half the smaller side for rectangular stock, or half the smaller leg/web/flange thickness for open sections.

For example, a relative thickness of 0.2 on a 10 mm-radius tube resolves to 2 mm. Relative values are useful when one attachment type should scale with several member diameters; absolute values are useful when a manufacturing constraint must remain fixed in millimetres.

The attachment also receives available link length in both directions and the section inputs shared by every host in its supported set. Circular types can use radius; rectangular types can use width, height, and edge radius; open-section types can use their widths, heights, thicknesses, and radii. Wall thickness is available when every supported host is hollow. These inputs are read-only in the Frame Editor.

End pinning#

Pinned to end is a position guard for terminal attachments.

• With pinning off, the authored offset remains authoritative.
• With pinning on, the editor derives the offset that places the attachment flush with the nearest end of the Physical link.

The offset control is disabled while it is derived. Changing attachment length or parent-link length recomputes the pinned offset automatically. A Physical-link attachment longer than its parent member cannot be pinned to that member's end.

If the chosen anchor is not a terminal node, the editor leaves the attachment unpinned even when the default requests end pinning.

Implementation type and parameters#

The Type field chooses one compatible Physical attachment definition imported into the frame's Attachments catalogue. That definition owns the CSG recipe, parameter schema, body parts, connection ports, and clearances.

Compatibility includes profile family and solid/hollow construction. A circular-only sleeve does not fit rectangular stock automatically, and common field names do not make L/T/I/U families interchangeable. Author a compatible type in the Attachment Editor when the catalogue has none.

The selected instance stores explicit parameter values for that type. Changing a parameter regenerates the attachment with the same parent placement. Changing the type may change its available parameters, body parts, connection eligibility, and geometry.

Use the Attachment Editor when the required type does not exist. Frame Editor instances configure and place reusable types; they do not author primitives or boolean operations.

Body parts, materials, and clearances#

An attachment type may resolve to one or several named body parts. Body parts are the units used for material assignment, manufactured geometry, and printable-component grouping.

A simple attachment may expose one material for its whole body. Multi-part types can expose per-body-part material controls. Separate connection ports identify the selectable regions that may participate in Attachment Connections; each port names the body part that supplies its material and manufactured geometry.

For default-based placement, authored per-body material preferences take priority over the Frame fallback. Existing instances retain their concrete assignments when defaults change. See authored material preferences.

Clearances are subtractive geometry authored by the attachment type. The Frame Editor carries them into the connected printable component so neighboring bodies leave room for the tube, fastener, insert, or other required interface.

Propagation#

A Physical-link attachment follows changes to:

• its anchor node and parent member placement;
• compatible parent section dimensions and, for non-circular hosts, section roll;
• its own length, thickness, offset, orientation, type, and parameters;
• end pinning;
• connected body-part materials and Attachment Connections;
• Frame reactive properties referenced by its expressions.

The editor updates the attachment, affected connection geometry, shared clearances, and material continuity in the same reversible transaction.

Creating and editing Physical-link attachments#

Import the required Physical attachment type into the frame's Attachments catalogue. Open + Add, choose the type under Attachments, then select any highlighted compatible node in the 3D view. The editor evaluates every Physical link in the frame and assigns the attachment to the compatible parent member represented by the chosen node.

The link-local route remains available when the parent matters more than the type: select a Physical link, choose Add attachment, then select an eligible anchor node on that member. That route uses the frame's default Physical attachment type for the member's host profile.

The main editing actions are:

• rename the attachment;
• move it to another eligible host or anchor node;
• follow its node or parent-link references;
• edit length, thickness, and offset modes and expressions;
• toggle Pinned to end;
• change type and implementation parameters;
• choose whole-attachment or body-part materials;
• flip direction, or rotate independently around a circular member axis;
• start an Attachment Connection from a connection port;
• hide, show, or delete it.

Add missing attachments is a bulk convenience for filling eligible member locations from defaults. Use explicit placement when terminal choice, orientation, or teaching intent must remain visible.

Moving an existing attachment#

Select the attachment and choose Move. Green target rings mark eligible nodes on compatible Physical links. Hover a link near a ring to preview the configured attachment, then click to move it. The move finishes immediately and keeps the attachment selected. Cancel Move or Exit leaves it at its original location.

Moving keeps its definition, parameter expressions, sizing modes, end pinning, materials, visibility, and valid connections and mounted parts. Relative sizes resolve against the destination host; direction and roll transfer with its orientation. A non-circular Physical host keeps its existing roll lock. Destinations that are occupied or would invalidate the configured attachment or its retained relationships are omitted. Physical attachments remain Physical, and Virtual attachments remain Virtual.

Common mistakes#

• Anchoring from a nearby logical node that is not on the parent member. The anchor must belong to that Physical link's reference span.
• Assuming “relative” means a percentage of member length. Physical attachment length, thickness, and offset use the profile's reference length, which equals radius only for circular stock.
• Editing a disabled offset. Turn off Pinned to end when manual offset ownership is intended.
• Using rotation to reverse direction. Use Flip direction for the axial reversal, then rotate only for roll.
• Expecting a type change to preserve incompatible port connections. A new type must still expose compatible port keys for existing connections.
• Treating hidden geometry as deleted. Visibility changes only the scene presentation.

Related learning#

Read the concept series chapter for the illustrated explanation in context.

Watch the Triangle Frame narrated build add Tube Sleeves to reconciled member ends and carry them through a later geometry change.

Read Physical links for parent-member properties, Virtual-link attachments for the non-member alternative, or Attachment Connections for combining connection ports.