In Fusion, there's a tool that allows you to split a design without having to create a sketch or have a plane in the correct location. This automatically creates a parting line, which is great for mold design, CAM, and simulation.

⏱️ 0:26 – Where to find Silhouette Split

Go to Modify and find Silhouette Split. It’s similar to Split Body and Split Face — an automated tool for splitting geometry.

How It Works

When you click this tool and go to View Direction, you’ll select a face, plane, or axis — anything that provides direction.

If I select a face and a target body, then click OK, Fusion creates a parting line and splits the body (if selected).

⏱️ 1:03 – Understanding what Fusion calculates

To understand what it’s doing, use a Section Analysis. You'll see the silhouette curves generated at the widest points of your geometry.

Tapered Shape Example

If the face tapers, Fusion calculates the widest areas — typically near the base — and places the split accordingly. If it can't find two wide points, the tool won’t solve.

⏱️ 2:24 – Example: View direction from the bottom face

Using the bottom face as a view direction, Fusion finds the widest location and creates a split plane right in the middle.

Free Resource Mention

⏱️ 2:43 – Mention of the Fusion shortcut library

I’ve created a free Fusion 360 library with cheat sheets — including shortcut desks. Check the link in the description.

When Silhouette Split Fails

If there’s only one wide side (like a tapered model), Fusion can’t place the split — there’s no midpoint to calculate. Try Split Face instead.

Custom Splits

⏱️ 3:53 – Using sketches for custom splits

You can sketch anything — like a spline — and use Split Body to make a custom cut. Or use surfaces to control the split. Silhouette Split is faster, but more limited.

Tool Options Overview

⏱️ 4:15 – Options inside the tool

• View Direction: Use planes, axes, or faces.
• Target Body: Simpler geometry works best.

Split Face Flexibility

⏱️ 5:01 – When to use Split Face

Split Face is less strict than Silhouette Split. It allows you to split surface regions without cutting the body into two. It’s useful for aesthetics, selections, or prep for additional features.

Final Thoughts

Silhouette Split works well for automatically generating parting lines — especially on co-planar faces.

• Use Split Body for full control.
• Use Split Face when you need selectable zones.
• Use Silhouette Split to save time on simple parts.