Branching and Merging

Overview#

Software developers take branching and merging for granted. Mechanical CAD is harder, because a design is a binary file with a geometric kernel, not mergeable text. Fusion's design history is linear: a sequence of changes and versions with no fork inside a single file. Autodesk's Fusion documentation describes no branch or merge command for designs. Yet teams constantly need parallel work: an experimental redesign while production continues, two customer variants, a risky change that may be thrown away.

This page explains the techniques that provide branch-like behaviour in Fusion, and where each one is weak. The only place the documentation uses the word is a tip for Save As: with Include Drawings selected, drawings stay associative with the new design, "so you can branch and reuse designs while keeping drawings up to date". The only "merge" in the documentation is hub merge (consolidating two hubs, covered on the hubs page), which is not a design merge. Where Fusion has no native merge, we say so plainly and show how to merge by hand.

Where to find it#

• Save As: File > Save As saves the open design with a new name or location, optionally with Include Drawings, and lets you choose New Part Number or Shared Part Number. The original is unchanged.
• Copy: right-click a design or folder in Fusion Home or the web client and choose Copy (Viewer or higher at the source). Messages in the Notification Center report progress.
• Save As and Replace / Replace Component: right-click an external component in the Browser.
• History: Data Panel > expand the design details > History, or right-click a component in the Browser > History; entries open in a separate tab.
• Derive and Insert Derive: Design workspace, Solid tab: Create > Derive and Insert > Insert Derive.
• Configurations: the Configurations feature (Configuration Table, Configuration Mode); see the Configurations section of this guide.

Choosing a branching strategy#

Not every parallel need warrants a branch. Match the tool to the need.

Technique 1: milestone and roll back#

This is the lightest "branch". Before risky work:

1. Save and Create version with the description PRE-EXPERIMENT. (Education: save as a milestone.)
2. Continue editing and saving.
3. If you like the result, keep going. If not, open the PRE-EXPERIMENT entry from the History dialog (it opens with an Out-of-Date icon) and use File > Save As Latest. The failed experiment remains in history, but the latest state is again the good design.

Limits: the experiment and the mainline cannot both be latest at once. If a teammate needs the mainline while you experiment, this approach fails. Also note that Save As Latest resets bill-of-materials quantity overrides to design values, and the saved design does not include newer changes made by others in the meantime. If Design Reservation is enabled by your team administrator, the design is reserved to you while you hold savable changes; Read-Only For Me lets a teammate look without blocking you.

Technique 2: copy as a fork#

Create a separate file that starts as a clone.

1. Right-click the design in the Data Panel and use Copy, or open it and use File > Save As with a new name such as MXC-A-0001_Housing_VariantB.
2. Choose the destination folder, ideally a Variants or Branches folder.
3. If the design has external references, decide whether to copy them too. Save As creates a copy of the parent only: the copy still references the components found in the original, so edits to shared components affect both variants. Copy of a folder or several designs updates references between components that were copied together to point at the new copies; references to components that were not copied stay unchanged. Save As and Replace (or Replace Component) swaps selected external components in an assembly for copies of themselves.
4. Work on the copy. Copying a design to another hub resets its history; a copy in the same hub is a new design saved in the new location (the documentation does not say whether its history is reset).

Strengths: complete independence, clear ownership. Weaknesses: the documentation describes no automatic "branched from" link, so record the origin yourself in the version description: "Forked from MXC-A-0001, version 12". Parts that need to remain identical across both forks should stay as shared references, not copies.

Technique 3: derive and insert for linked variants#

Derive (Solid tab > Create > Derive, with destinations Create New Design or Add To Existing Design; or Insert > Insert Derive into the active design) links design features from one design into another. A Derive feature is added to the Timeline and derived parameters appear in the Parameters dialog. Use cases:

• A mold design derived from the part so it follows geometry changes.
• A variant that must always track the master body.

This is "inheritance" rather than a branch; the master stays authoritative and the variant adds features on top. Derive lets you select components, bodies, sketches and construction geometry, plus Favorites or From Components parameters. The documentation does not describe pushing changes back to the source. As general guidance, treat the link as one-way and expect edits to the master to be able to break downstream features.

Technique 4: configurations#

Configurations (a Configuration Table of variants within a single Configured Design) let one design produce several variants by reusing parametric logic: dimensions, materials and appearances, and swapped components via Configurable Assemblies. It is the correct answer for "same product, many sizes". It is not a branch for long-lived divergence, since all variants share one design. The Configurations overview does not state a plan restriction; check your subscription. A configured design cannot itself be versioned, but you can version one of its configurations.

Merging: what actually works#

There is no general automatic geometry merge in plain Fusion. The reliable options are manual:

Merge by copying features#

1. Open the branch design (the fork) and the mainline in separate tabs.
2. In the fork, select the features in the timeline that you want to keep.
3. Copy them (Ctrl+C) and paste into the mainline timeline with Ctrl+V.

Note: not confirmed in Autodesk's documentation: copying timeline features between designs. Test it on a scratch copy first; as general experience, sketch references to missing geometry fail.

4. Resolve failed features (red marks) by redirecting to the mainline's geometry.
5. Save with the description "Merged feature set X from fork B".

Merge by parameters#

When the difference between branches is only numbers, merging means aligning user parameters. Compare the Parameters dialog (the Change Parameters tool) in both designs, update the mainline and save. This is the easiest and safest merge, which is a strong argument for parametric modelling with named parameters (see section 04).

Merge by body import#

For geometry that was entirely redesigned in the fork, bring the fork's bodies into the mainline (for example with Insert Derive, which keeps a link, or by copying bodies), then use Combine to integrate. A combined body carries no history from the fork (general behaviour).

Merge by replacing the reference#

For assemblies, merging a component branch means pointing the assembly at the new file: right-click the external component in the Browser, choose Replace Component, pick the other external design, and optionally tick Replace All Instances. If the replacement is a direct copy of the original, Fusion reconnects joints and assembly contexts. Then archive the old file.

Handling conflicts#

A conflict in CAD means two changes touch the same geometry. Examples: both branches moved the same hole, or one deleted a face that the other references. There is no three-way merge tool. Prevent conflicts instead:

• Split work by component so each file has one owner.
• Reserve the master assembly for integration.
• Use timeline groups and named features to see intent quickly.
• If your team administrator has turned on Design Reservation, use it: it reserves a design while someone has savable changes, so two people do not save conflicting edits.
• Review both versions together on a call, then choose which change wins, then recreate the winning change in the master by hand.

Step by step: run a customer variant#

1. In the master assembly, Create version with the description BASE-RevB.
2. Create a Variants folder.
3. Copy the assembly, rename ..._CustB, save in Variants.
4. Copy only those components that must change (Save As and Replace does exactly this from the assembly); keep the rest as shared references. Use Replace Component to swap in other variant parts.
5. Document in the variant's description: "Fork of BASE-RevB; changes: bore 12 mm, logo plate".
6. Work on the variant. When the master moves to Rev C, review the changes and port them by hand to the variant, or decide to retire the fork.
7. When the project is done, archive the variant folder.

Branching and Fusion Manage#

Heavy-duty PDM and PLM systems model branching explicitly: a revision tree, work-in-progress copies, and controlled merges via change orders. Fusion Manage manages items and change orders (the formal release layer): items move through the lifecycle states Unreleased, Pre-Production, Production and Obsolete as change orders progress, and releasing a new revision supersedes the previous one rather than branching it. CAD files in Fusion are branched by copying, as above. See the PDM concepts page.

Options reference#

Tips and pitfalls#

Tip: Prefer parametric variants (configurations or parameters) to forks. Each fork doubles the maintenance work.

Tip: Put the branch origin in the file description and in the project README so the lineage is recoverable.

Warning: When using Save As on an assembly, check the Uses tab. Components still pointing to the originals mean edits will cross-contaminate branches.

Warning: Merge by timeline paste is fragile with long timelines. Do it in a scratch copy, test, then save.

Warning: Branch-and-merge terminology varies across Autodesk products. The Fusion documentation describes no design branch command, so do not assume one exists in your client.

Practice exercise#

Take a simple bracket with a named parameter thickness. Create a version. Make a fork called Bracket_Heavy and change thickness to 6 mm and add a rib. In the original, add a chamfer. Then merge: copy the rib from the fork into the original, and reconcile thickness by deciding which value wins. Expected result: the original contains the chamfer and the rib, both documented in the version description, with no failed features in the timeline.

Related#

• Versions, Milestones and Lifecycle States (this section)
• Fusion Manage and PDM Concepts (this section)
• Hubs, Projects and Folder Architecture (this section)
• Getting started: Versioning and Milestones