Groups and bodies

A document consists of an ordered list groups. Each group contains entities and constraints that result in a set of equations that gets solved. Groups are solved in the order they’re in the document. Once a group is solved, the position of its entities can’t be modified by subsequent groups.

Groups can optionally have an active workplane. It can be in the same or any previous group. Use the “Set workplane” and “Clear workplane” tools to change the active workplane. With an active workplane, it becomes possible to draw entities in 2D space in that workplane.

Groups can be reordered with the restriction that a group and its entities and constraints must only reference the group itself or previous groups.

Deleting a group will also delete all dependent groups and entities.

Bodies break up the solid model, in the way that the first group in a new body isn’t aware of the solid model of the preceding body. Bodies have no effect on entities and constraints and can be created and removed without adverse effects. That way, bodies are useful to create parts consisting of multiple sub-parts such a box with a lid. To add a body, select the checkbox next to “Body” in the Group tab.


A reference group is the first group in any document. It automatically contains three workplanes, one for each axis. Neither the group nor its workplanes can be deleted. Reference groups can’t be added explicitly.

It’s possible to add entities in the reference group, but not recommended.


A sketch group is meant for adding entities either in a set workplane or in 3D.


An extrusion group extrudes closed paths from the source group’s active workplane along the extrusion vector. When creating an extrusion group, the current group and its workplane become the source of the extrusion group. The workplane reference is stored in the extrusion group, so changing the active workplane of the source group has no effect. To create an extrusion group, the current group must have an active workplane.

If the “along normal” switch is on, the extrusion vector is along the source workplane’s normal and the group has one degree of freedom instead of three.

Setting the mode to offset adds one extra degree of freedom to change the start of the extrusion to an arbitrary point along the extrusion vector.

If there is no preceding solid model in the current body, the operation (union or difference) has no effect.

It’s possible and supported to create multiple disjoint solids in one extrusion group.


A lathe group rotates closed paths from the source group’s active workplane along a specified point and vector. To specify it, either a line or a workplane must be selected when creating the group. If a workplane is selected, lathe group is based on its normal vector.

A lathe group adds no degrees of freedom.

Operation has the the same semantics as in extrusion groups.

Linear array

A linear array group replicates entities from its source group as often as specified in “Count” along a vector. Its detailed operation depends on whether it has an active workplane or not.

If it has an active workplane, the vector is in that workplane so it adds two degrees of freedom. Entities from the source group in the same workplane will be copied, as well as entities in 3D space. Entities in other workplanes won’t be copied.

If it has no active workplane, the vector is in 3D space so it adds three degrees of freedom. Only entities in 3D space will be copied from the source group.

Setting the offset to “original” places the first copy at the same location as the entities from the source group.

Setting the offset to “first copy” places the first copy one vector away from the original.

Setting the offset to “arbitrary” places the first copy at an arbitrary point, adding two or three degrees of freedom.

If the source group has a solid model, its operation is repeated for each instance of the array.

Polar array

A polar array group replicates entities from its source group as often as specified in “Count” in circular fashion centered around a point. A polar array group always requires a workplane to specify the plane of rotation. To create a polar array group, select a workplane first.

By default, it adds three degrees of freedom: Two for the center point position, one for the angular increment.

The offset and handling of the solid model work just like in the linear array group.

Fillet / Chamfer

Unlike the other groups, these only operate on the body’s solid model and don’t create any entities. Use the “select edges” tool to select the edges the fillet/chamfer is applied to.

Unlike everywhere else, these edges are references to features in the solid model and thus are subject to the topological naming problem. Therefore, it’s recommended to apply these operations as the last step in the document’s modelling sequence.