Make a part lighter, using branches

"Make it lighter" sounds like one request, but there are many ways to do it: thinner walls, pockets, lightening holes, ribs, a different material, a smaller part. Each trades weight against strength, stiffness, print time, and looks. A good approach is to try several, compare honestly, and keep the winner.

That is exactly what branches are for.

1. Set a goal and protect what matters

Before changing anything, decide what must not change. Write it as design intent, so it holds across every experiment:

Always keep the 8 mm bore, the overall diameter of 60 mm, and the 4 mounting holes unchanged. Never let a wall be thinner than 1.6 mm.

Note the starting weight. Ask:

What does this weigh in PETG, and how long does it take to print?

2. One branch per idea

Create a branch for each approach. Name it after the idea.

Create a branch called lightening-holes from here. Add a circular pattern of lightening holes through the web of the gear. Keep at least 3 mm of material between holes and around the hub.

Then go back to main and try another:

Create a branch called thin-web from main. Reduce the web thickness from 8 mm to 4 mm, keeping the hub and the rim at full thickness. Add a 1.5 mm fillet where the web meets the hub.

And a third:

Create a branch called ribbed from main. Thin the web to 3 mm and add 6 radial ribs, 2 mm thick, for stiffness.

Each one is a safe experiment. Main stays untouched.

3. Compare with the visual diff

Open the diff between a branch and main:

• Red shows material you removed.
• Green shows material you added.
• The parameter changelog lists the numbers that changed, such as "Weight 142 g to 118 g".

Put the results in a small table:

(The numbers here are illustrative. Yours will come from your model.)

4. Check printability and function

For each promising branch, open Make and run the check. A lighter part that needs supports, or has thin features that will not print, is not really an improvement.

Function checks matter more than numbers. Ask:

Compare the thin-web and ribbed branches. Which is stiffer for a gear that sees 0.5 N-m of torque, and why? Be honest about uncertainty.

The agent can reason about it, but it is not a stress analysis. Quick simulation that returns a stress heatmap and a safety factor is coming later. For parts that matter, print the candidate and test it.

5. Merge the winner

When one branch earns its place:

• Merge the branch into main to bring everything across.
• Cherry-pick specific features if you like parts of different branches, such as the ribs from one and the holes from another.

Delete or keep the losing branches. They cost nothing, and they are a record of what you tried and why it lost.

6. Tag it

When the new version is final, add a release tag, such as "v1.1-lighter". It freezes the geometry together with its Make list, so you can always reproduce what you shipped.

Other ways to lighten a part

Try it

On the Spur gear template, with a plan that includes branches:

Make a branch called lighter. Add 6 lightening holes through the web, evenly spaced on a circular pattern, each 10 mm in diameter. Keep the bore and the teeth unchanged. Then show me the weight change against main.