Fillet

The fillet command rounds the corner between two Line entities by inserting a tangent arc of a given radius and trimming each line back to the point where the arc begins. The result is a smooth, radiused corner connecting both lines.

Fillet works on Line entities only.

Using fillet

1. Type fillet in the terminal or click the Fillet toolbar button.
2. Type the fillet radius and press Enter.
3. Click the first line — the portion you click determines which side of any intersection is kept.
4. Hover over the second line — a dashed arc preview shows the resulting fillet. Move the cursor to the side you want to keep.
5. Click to apply. Both lines are trimmed and the arc is inserted.

  Before:                     After fillet (radius r):

  ──────────────              ──────────╮
                │                        ╰────
                │

Side selection for intersecting lines

When two lines cross each other, the fillet is applied on the corner defined by the click positions — the portion of each line on the same side as the cursor is kept.

• Click near one end of the first line to select that half.
• Move the cursor to the desired half of the second line — the dashed preview updates live.

What the command creates

• The first line's endpoint nearest to the intersection is moved to the tangent point T1.
• The second line's endpoint nearest to the intersection is moved to the tangent point T2.
• A new Arc entity is inserted from T1 to T2, tangent to both lines.

The inserted arc inherits the current lineweight, color, layer, and linetype settings.

Keyboard reference

Key	Action
0–9, .	Append digit to the radius value
Backspace	Delete last typed character
Enter	Confirm the typed radius and move to line selection
Escape	Cancel and reset

Supported entities

Entity	Supported
Line	Yes — as both first and second entity
Arc, Circle, Ellipse, Polyline	No
Text, Spline, Dimension, Leader	No

Fillet vs Chamfer

	Fillet	Chamfer
Corner type	Rounded arc	Straight cut
Input	One radius	Two distances (d1, d2)
Inserted entity	Arc	Line
Supported entities	Lines only	Lines and Polylines