---
title: Bisect
order: 4
---

Bisect cuts a shape with a plane and throws one side away. No cutter shape is needed, and the cut edge takes the same blend profiles the booleans use. A **Polyline** Bisect cuts with a fence of connected planes instead.

![a box cut by a tilted plane, with a blended edge](../assets/bisect.webp)

## Settings

The panel header says which kind a Bisect is: a single **Plane**, or a **Polyline** fence. Bisects added from the menus are planes; the Chisel tool's Polyline drawing makes fences.

### Plane

![a Bisect with a Custom plane in the panel](../assets/modifiersettings-bisect-plane.webp)

| Setting | Default | Range | What it does |
|---|---|---|---|
| **Plane Source** | **Object** (**Custom** when added to one shape) | Object / Custom | Where the plane comes from |
| **Plane Object** | | any object (*Object*) | Its origin is a point on the plane and its local **+Z** the normal; moving it moves the cut. Empty: the shape's own origin and Z, with no handles |
| **Location** | `0, 0, 0` | (*Custom*) | A point on the plane, in the shape's own space, so the plane travels with the shape |
| **Normal** | `0, 0, 1` | (*Custom*) | The plane's normal, in the shape's own space. The side it points to is cut away |
| **Flip** | off | | Keep the other side of the plane |
| **Blend** | off | | Round the cut edge with the settings below. A [Smooth](smooth.md) on the stack rounds the cut edge too |
| **Profile** | Round | Round / Sharp / Soft / Tight / Chamfer | The shape of the blend; see [Profiles](../rounding-and-blending/profiles.md). Chamfer adds a **Smooth** row (`0` and up, soft `0.5`) that rounds the chamfer's edges |
| **Outer** | `0` m | `0` and up (soft `2`) | The blend radius. `0` is a hard, exact cut |

### Polyline

A fence is a row of planes, one per drawn segment. The planes at the two ends carry on past the ends of the drawn line.

![a Polyline Bisect with two planes in the panel](../assets/modifiersettings-bisect.webp)

| Setting | Default | Range | What it does |
|---|---|---|---|
| **Plane 1** | | | The first plane. It starts the fence, so it has no fold or corner |
| **Location** | | | The plane's point (its segment's middle), in the shape's own space |
| **Normal** | | | The plane's normal; it points at the side that gets cut away |
| **Plane 2**, 3, … | | | Every later plane, in drawing order |
| **Fold** | from the drawn turn | Union / Intersect | **Union** cuts where this plane *or* the planes before it cut; **Intersect** only where both do |
| **Corner Blend** | `0` m | `0` and up (soft `2`) | Rounds the crease where this plane meets the one before it. `0` is a hard corner. A Smooth modifier leaves it alone |
| **Profile** | Round | five profiles | The corner's profile, shown while *Corner Blend* is above `0`. Chamfer adds a **Smooth** row |
| **Flip** | off | | Keep the other side of the whole fence |
| **Blend** | off | | Round the fence's cut edges, with *Profile* and *Outer* as on a plane |

## Add Bisect

With one shape selected, the Bisect gets a *Custom* plane at the shape's origin, along its local Z. With several, every shape except the active one is cut by a plane through the active shape's origin, facing along its local Z (an *Object* plane). **Each Its Own** in the redo panel (`F9`) gives every selected shape its own *Custom* plane at its own origin instead; the [Tape tree](../interface/tape-tree.md)'s **+ Mod** always adds a Bisect that way.

`Ctrl + D` on a cut shape copies its plane object only if the plane object is selected too, or parented to the shape. Otherwise the copy cuts against the same plane object.

## Bisect mode

With the Chisel tool in [Bisect mode](../interface/active-tool.md#bisect-mode), a left drag draws the cut across the selected shapes. Each gets its own Bisect through its own origin. The shaded side of the preview is cut away. By default the side holding most of the selected shapes is kept.

![Bisect mode, Line: drag across the shape, F to flip the side, release](../assets/bisect-line.webp)

**Polyline** in the tool header draws a fence: drag the first segment, click to add corners. Each segment becomes one plane.

![Bisect mode, Polyline: drag, click two corners, Backspace removes the last, Space accepts](../assets/bisect-polyline.webp)

| Key | Line | Polyline |
|---|---|---|
| **LMB-drag** | Draw the cutting line | Draw the first segment |
| **LMB-click** | | Add a corner |
| `Space` / `Enter` | Confirm | Accept the fence |
| `Backspace` | | Remove the last corner |
| `F` | Flip the kept side | Flip the kept side |
| `Ctrl` | Toggle angle snap | Toggle angle snap |
| `Shift` | Precision | Precision |
| `RMB` / `Esc` | Cancel | Cancel |

## Gizmo

Every Bisect on the active, selected shape draws its handles while the Chisel tool is active. Click a Bisect's row in the [Tape tree](../interface/tape-tree.md) to show only its handles.

![tilting a plane with its white ring, Ctrl to snap, then a click on the arrow flips the cut](../assets/bisect-gizmo.webp)

| Handle | Looks like | Drag or click | Keys while dragging |
|---|---|---|---|
| Arrow | Blue arrow on every plane, pointing at the side that gets cut away | Drag to slide the plane along its normal (an *Object* plane moves its object). **Click** to flip the kept side; on a fence the whole fence flips | |
| Blend dot | Small orange dot beside the plane, toward the right of the screen | Drag away from the plane to raise the cut-edge blend. Raising it from `0` ticks **Blend**; back to `0` leaves it ticked | `1`–`5` profile, `S` chamfer smooth (Chamfer only) |
| Tilt rings | Two white rings on a dashed square around a single plane | Drag one to tilt the plane about its anchor | `Ctrl` snap `15°` (`Ctrl + Shift`: `5°`), `Shift` precision |
| Fence points | Blue dot on every point of a fence | Drag to move the point; the planes on both sides follow. Hover and press `X` or `Delete` to remove it; a fence keeps at least two | `Ctrl` slide along a segment, `Shift` precision |
| Add dot | Green dot at a fence segment's middle, when you hover near it | Click to add a point there | |
| Corner dots | Small orange dot off every corner of a fence | Drag to set that corner's **Corner Blend** | `1`–`5` profile, `S` chamfer smooth |

![dragging the blend dot, then 5 for a Chamfer](../assets/bisect-blend-dot.webp)

![moving a fence point, then adding one](../assets/bisect-fence.webp)

The blend and tilt drags show their value beside the cursor. `Space`, `Enter` or releasing the mouse confirms; `RMB` or `Esc` cancels and restores everything, the plane object's position included.

In the Chisel tool's [Edit](../interface/edit-mode.md) state, fence points select like the points of a shape: click, `Shift`-click or drag a box, then drag one of them or press `G` to move them all, `X` to remove them.

Switch the handles in the tool header's [gizmo drop-down](../interface/gizmos.md#tool-bar-switches) or in *Render Properties ▸ Gizmos ▸ Modifiers ▸ Bisect*: **Bisect Gizmo** (all of it), **Blend Handles**, **Fence Points** and **Tilt Handles**.

## Pie menu

The pie's East wedge has a row per Bisect: the flip button, the five profile icons, the blend radius, the chamfer smooth and the plane's name.

## Limits and known issues

> [!warning]
> In 5.0.0 the arrow and fence point drags show no value beside the cursor, and the status bar of a blend drag always lists `[S]`, though `S` works only with the Chamfer profile.

## See also

- [Boolean](../joins/boolean.md): cut with a shape instead of a plane
- [Mirror](mirror.md): reflect across a plane instead of cutting