How to Draw Helixes in BricsCAD

Quick answer: A helix turns about an axis on the surface of a cylinder or cone while rising at a constant angle from its base. A spiral is a flat, planar curve winding around a fixed centre point at an increasing distance. Both are created with the same HELIX command, the difference comes down to the height value you enter at the final step: zero produces a spiral, anything else produces a helix.

Finding the Helix Tool

The Draw menu, the Polylines toolbar (not the general Draw toolbar), or the Draw ribbon panel.

Drawing a Spiral: General Procedure

1. Launch HELIX (defaults to 3 turns, counterclockwise twist). You’re prompted for the centre point of the base.
2. Specify a point. You’re prompted for a base radius, or to switch to diameter.
3. Either specify a point or type a value and press Enter. You’re prompted for a top radius.
4. Either specify a point or type a value and press Enter. You’re prompted for the helix height, or to choose Axis endpoint, Turns, turn Height, or tWist.
5. Type 0 and press Enter. A height of zero is what makes this a spiral rather than a helix.

Drawing a Helix: General Procedure

1. Launch HELIX (defaults to 3 turns, counterclockwise twist). You’re prompted for the centre point of the base.
2. Specify a point. You’re prompted for a base radius.
3. Either specify a point or type a value and press Enter.
4. Either press Enter to set the top radius equal to the base radius (producing a cylindrical helix), or specify a different point or value (producing a conical helix instead). You’re prompted for the helix height.
5. Specify a point or type a non-zero value and press Enter. The helix is created.

Editing a Helix

Select it, and its properties appear in the Geometry category of the Properties panel:

• Constrain: locks either the overall height, turn height, or number of turns; the other, unconstrained properties adjust automatically. Height equals turn height multiplied by turns.
• Height: the overall height.
• Turns: the number of turns.
• Turn height: the height of a single turn.
• Base radius and Top radius: the start and end radii.
• Twist: clockwise or counterclockwise.

Setting Top radius equal to Base radius keeps it cylindrical; setting Height or Turn height to zero turns it into a spiral.

Converting a Helix

Run EXPLODE on a helix to turn it into a spline.

Frequently Asked Questions

What’s the actual difference between a helix and a spiral in BricsCAD? Both come from the same HELIX command. A height of zero produces a flat spiral; any other height produces a proper 3D helix.

How do I create a conical helix instead of a cylindrical one? Give it a different top radius than base radius when prompted, rather than pressing Enter to keep them equal.

Can I change a helix’s number of turns after creating it? Yes, edit it in the Properties panel’s Geometry category. Use Constrain to decide whether height, turn height, or turns stays fixed while you adjust the others.

How do I turn a helix into an editable curve like a spline? Run EXPLODE on it.