How to Use Direct Modelling Operations in BricsCAD

Quick answer: Direct modelling in BricsCAD covers aligning the UCS to a solid face, selecting geometry precisely, moving faces to control dimensions, making holes, deleting features, cleaning up coplanar edges, copying features between solids, stretching with grips, and deforming faces for organic shapes.

Controlling the Coordinate System

Since entities are created in the XY-plane of the current UCS, you need to align the UCS with the solid face you’re working on. Two ways:

• The Align UCS tool launches UCS with the Face option already selected.
• Click the DUCS field in the Status Bar to toggle Dynamic UCS. When on, the UCS aligns automatically to the solid face under your cursor as you execute a command, with the icon updating to match. Press Tab to select an obscured face, and Shift to temporarily lock the UCS in place, letting you work outside the hovered entity or face; press Shift again to unlock it.

Selecting Geometry

Press Tab to select obscured geometry. SELECTIONMODES controls which subentities highlight (edges, faces, and/or closed boundaries); hold Ctrl to override it and select whatever’s directly under the cursor instead. For window selection of faces or edges, press Ctrl to cycle through the options, the icon beside your cursor shows what will be selected.

DMSELECT lets you select edges and faces based on their actual geometric and topological properties:

• Edges of a particular length.
• Edges forming a concave or convex network.
• Edge loops on the border of a set of connected faces.
• Faces of a particular area.
• Smoothly connected faces, either G1 (tangent) or G2 (curvature continuity).
• Fillets of a specific radius.
• Cylindrical protrusions of a specific radius.
• Protrusion or depression features: pockets, extrusions, or ribs.

You can pull the target length, area, or radius directly from an already-selected edge or face rather than typing it manually.

Moving Faces with DMPUSHPULL

Make sure the Quad and Dynamic Dimensions are both on.

1. Hover over the face you want to move; it highlights.
2. Choose Push/Pull in the Model tab of the Quad. The face moves with your cursor, and a dynamic dimension field with a ruler shows the relative distance. On the ruler, the face moves in fixed intervals (zoom in or out to change the interval); off the ruler, it moves freely.
3. Optionally press Tab repeatedly to measure the distance relative to a different internal or parallel reference face instead; hold Shift and press Tab to reverse the order references cycle in.
4. Either type a value into the dynamic dimension field and press Enter, or click on the ruler at the value you want.

Making Holes

Method 1, Boolean subtraction:

1. Create the subtractor solid.
2. Run SUBTRACT. Depending on DELETETOOL, the subtractor solid is either deleted or kept afterward.

Method 2, extruding an opening directly:

1. Create the outline of the opening on the solid’s face.
2. Hover over the outline and choose Solid Extrude (DMEXTRUDE, a command not listed among the core direct modelling commands but genuinely part of this workflow) in the Model tab of the Quad.
3. Move the cursor inside the solid to create the opening.
4. Either specify a point or type a value.

Making a hole in a surface specifically:

1. Create a 2D closed entity, an ellipse, for example.
2. Hover over it and choose Solid Extrude (DMEXTRUDE) in the Model tab of the Quad.
3. Extrude it in the surface’s direction; the default direction is perpendicular to the 2D entity’s own plane. The Hotkey Assistant appears at the bottom of the screen.
4. Press Ctrl twice to select DMEXTRUDE‘s Subtract option.
5. Click to create the opening.

Deleting Features

DMSELECT‘s Feature option makes it easy to select every face of a hole, depression, or protrusion at once. In the Mechanical workspace, dedicated Protrusion and Depression tools live in the Select panel of the Modeling ribbon tab and the Select tab of the Quad, though they’re part of the Sheet Metal toolbox, so check Available Tools in the Customize dialog if you don’t see them.

1. Click the Protrusion or Depression tool.
2. Select one or more faces of the feature; every adjacent face belonging to it gets detected automatically.
3. Click Erase.

Removing Edges Between Coplanar Faces

When faces become coplanar, after using DMPUSHPULL, for example, you may need DMSIMPLIFY to remove the now-unnecessary shared edges between them.

1. Launch DMSIMPLIFY. You’re prompted to select entities to simplify, or the entire model.
2. Select the solid and press Enter. The edges are removed.

Copying a Feature

DMCOPYFACES copies a depression (a hole, groove, or pocket) or protrusion (an extrusion or rib) to a new location, on the same solid or a different one. Make sure Dynamic UCS is enabled first.

1. Select every face belonging to the entire feature.
2. Click Copy Faces, available on the ribbon (Modeling > Edit > Copy Faces), the Direct Modeling toolbar, the menu bar (Model > Direct Modeling > Copy Faces), or the Model tab of the Quad.
3. Specify a base point. You’re prompted for an insertion point, or to choose Rotate or Multiple.
4. Optionally use Rotate to spin the copied faces around the UCS’s Z-axis, or Multiple to insert several copies at once.
5. Specify the insertion point. The feature copies across using dynamic UCS.

Stretching a Solid with Grips

Select an edge, face, or entire solid, and specific grips highlight: a square grip at the centre of a selected edge, a 3D grip at the centre of a selected planar face, and multiple 3D grips for cylindrical or spherical faces, letting you stretch quickly right in model space.

This option isn’t available in the BricsCAD Lite licence level.

Deformable Modeling

Tools on the Deform toolbar deform a set of adjacent faces on a solid or surface, useful for complex, organic shapes. Three things always hold true during a deformation:

• The external boundary (edges adjacent to only one of the selected faces) stays unchanged.
• The internal boundaries (edges adjacent to two of the selected faces) deform together with the faces.
• The initial continuity between the deformed faces, G1 (tangent) or G2 (curvature continuity), is preserved.

For a twist deformation specifically, you can also set the continuity between the deformed and fixed portions of the entity.

Four commands define a deformation: DMTWIST (twists the whole entity or a portion of it), DMDEFORMPOINT (moves a point on a face in any 3D direction), DMDEFORMMOVE (moves or rotates one or more edges), and DMDEFORMCURVE (replaces an edge with a curve you specify).

Frequently Asked Questions

Is grip-based solid stretching available in every BricsCAD edition? No, it’s not available in the BricsCAD Lite licence level.

What’s the difference between the two main methods for making a hole? Method 1 uses Boolean subtraction with a separate subtractor solid and SUBTRACT. Method 2 draws the opening’s outline directly on the face and extrudes it inward with DMEXTRUDE.

What stays fixed when I deform a set of faces? The external boundary, the edges adjacent to only one of the selected faces, always stays unchanged, even as the faces themselves deform.

How do I select every face of a hole or protrusion without clicking each one individually? Use the Feature option of DMSELECT, or the dedicated Protrusion/Depression tools in the Mechanical workspace, which detect every adjacent face of the feature automatically once you select one.