How to Use Sketch Based Features in BricsCAD

Quick answer: A sketch based feature lets you edit the original 2D entity behind a 3D solid, and the solid updates automatically to match. EXTRUDE, LOFT, SWEEP, and REVOLVE (along with their Subtract and Unite options) create these when CREATESKETCHFEATURE is on, and the resulting features show up in the Mechanical Browser panel.

The Cross-Program Compatibility Warning

Worth knowing before you rely on this feature: sketch features created with CREATESKETCHFEATURE on aren’t compatible with other CAD programs. Saving such a drawing manually triggers a warning both in the Command line and as a balloon at the bottom right: “This drawing contains sketch features that are not compatible with other CAD programs. These features might break if you open the drawing using another CAD program!”

Converting Old Sketch Features

Opening a drawing containing older sketch features triggers an automatic conversion algorithm. If something goes wrong, you’ll be asked whether to continue:

• Yes: the algorithm does its best to convert the features, guessing the geometry of arbitrary ones. Converted Boolean features (Unite or Subtract) won’t be properly renamed, even though they’re treated as Booleans.
• No: the old sketch features are dissolved, keeping only the resulting 3D features, without the sketch-editing capability.

Creating a 3D Solid with Sketch Features

1. Turn on CREATESKETCHFEATURE.
2. Draw a 2D entity, a closed polyline, for example.
3. Optionally add parametrics to the sketch entity.
4. Launch EXTRUDE, LOFT, SWEEP, or REVOLVE to create the 3D solid feature, visible afterward in the Mechanical Browser panel.

Copying Sketch Features

SKETCHFEATURECOPYMODE decides how copies behave: on, a copy becomes fully independent of its source, with new blocks created for its sketches, paths, and guide curves; off, a copy shares those same sketches, paths, and guide curves with the original.

Editing the 3D Solid via Its Sketch

Each sketch feature exists as a block, moved onto a dedicated layer, BC_SKETCHES, which is off by default. Every sketch feature shows up in the Mechanical Browser panel.

Method 1: right-click the entity in the Mechanical Browser and choose Edit geometry. After saving your changes (BCLOSE), the 3D solid updates automatically.

Method 2: run BEDIT to open the Create or Edit Block Definition dialog, select the sketch feature, and it opens in the Block Editor.

Modifying a Sketch Based Feature’s Parameters

Method 1: click the solid in the Mechanical Browser and adjust its properties at the bottom of the panel.

Method 2: run UPDATESKETCH and specify the feature name, the parameter name, and its new value at the Command line.

Removing vs Deleting Sketch Features

To remove just the sketch features while keeping the 3D solid untouched, run REMOVESKETCHFEATURE or DISSOLVESKETCHFEATURE (the former does an additional purge afterward); both leave the drawing’s actual content unchanged. You can also choose Dissolve from a solid’s context menu in the Mechanical Browser.

To delete both the sketch features and their corresponding 3D solid entirely, run DELETESKETCHFEATURE, or choose Delete from the solid’s context menu in the Mechanical Browser.

Frequently Asked Questions

Can I open a drawing with sketch features in another CAD program safely? Not reliably. Sketch features created with CREATESKETCHFEATURE on aren’t compatible with other CAD programs and might break if opened elsewhere.

What’s the difference between REMOVESKETCHFEATURE and DISSOLVESKETCHFEATURE? REMOVESKETCHFEATURE does everything DISSOLVESKETCHFEATURE does, plus an additional purge step afterward. Both keep the resulting 3D solid intact.

If I copy a sketch feature to another drawing, does editing the copy affect the original? Only if SKETCHFEATURECOPYMODE is off, in which case the copy shares its sketches, paths, and guide curves with the source. Set it on, and the copy becomes fully independent instead.

How do I change a sketch feature’s dimension without opening the Block Editor? Run UPDATESKETCH and specify the feature name, parameter name, and new value directly at the Command line, or click the solid in the Mechanical Browser and adjust its properties there.