Can I draw an arc by specifying its start center and end in BricsCAD?

ByCADbrief Staff

Short Answer

Yes — in BricsCAD, you can draw an arc by specifying its start, center, and end points using the ARC command and choosing the Start, Center, End option. This is the most common professional method for precise arc geometry. One limitation: the end point must be geometrically valid for the chosen center.

What You Need to Know Before

Warning: If Object Snap is off or snaps are set incorrectly, the center or end point can be picked inaccurately and the arc will be created with the wrong radius or direction. This is especially common when selecting crowded geometry or working in rotated UCS views.

How to Draw an Arc by Start, Center, and End in BricsCAD

  • Command: ARC

  • Shortcut: A

  • Quick Steps:

    1. On the Ribbon, go to Home > Draw > Arc, or type A and press Enter.
    2. At the command line, choose the Center option after specifying the start point, or use the Start, Center, End input sequence when prompted.
    3. Pick the start point, then the center point, then the end point using Object Snap such as Endpoint or Center for accuracy.

Variables & Settings

  • Key Setting: Object Snap (OSNAP)

  • Expert Setting: Turn on precise snap modes such as Endpoint, Center, and Quadrant before starting the arc. This greatly reduces bad point picks and prevents small geometric errors that can break tangent or joined profiles later.

Why it Fails

  • Cause 1 (Geometry): The selected end point does not produce the intended arc from the chosen start point and center, often because the radius implied by the pick is wrong visually or direction is misunderstood.

  • Cause 2 (layers/Locks): The current layer is locked, so the arc cannot be created even though point selection appears to work.

  • Cause 3 (Command/Logic): The wrong ARC option is used, such as Start-End-Radius instead of Start-Center-End, which creates a different result than expected.

Quick Fix & Best Practice

  • Quick Fix: Turn on OSNAP, start ARC, and carefully pick Start, Center, and End from real snapped geometry instead of freehand clicking.
  • Manager’s Verdict: Use Start-Center-End when the center is known from design intent or existing geometry. Avoid it when the center is unknown; in those cases, a tangent-based or 3-point arc workflow is usually faster.

FAQ

Can I enter coordinates instead of clicking points?
Yes, you can type exact coordinates for the start, center, and end points during the ARC command.

Can I draw this arc from the command line only?
Yes, the ARC command fully supports command-line point entry and options.

Why is my arc going the wrong way?
The selected end point or point order changes the resulting sweep direction around the chosen center.

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