Top-hat bush & mould generator

import { LinkButton } from ‘@astrojs/starlight/components’;

A free tool for generating 3D-printable top-hat bush parts without touching CAD. Punch in the dimensions, hit download, slice and print.

Open the generator

What it does

Generates either:

• A dissolvable PVA mould — print in PVA, pour polyurethane in, dissolve in water, you’re left with a polyurethane bush. This is the workflow used on the Cheapest TVR Cerbera build for the rear-diff bushes.
• The bush itself — for printing directly in TPU or similar flexible filament if that suits your application.

Parameters

A “top-hat” bush has five core dimensions:

Parameter	What it is
Outer diameter (OD)	The main cylinder’s outer diameter
Inner diameter (ID)	The hole through the middle (for the metal crush tube)
Total length	Flange + crown, end to end
Flange OD	The “brim” diameter
Flange thickness	How thick the brim is

For the mould, two extra inputs control the mould geometry:

• Wall thickness — how thick the mould wall is around the cavity
• Bottom thickness — how thick the mould floor is under the cavity

Workflow (PVA mould)

1. Punch in the bush dimensions you need.
2. Download the mould STL.
3. Slice for PVA filament — single-perimeter walls are usually fine, the whole thing dissolves.
4. Print.
5. Block the bottom of the central pin recess if needed (some printers leave it open).
6. Mix and pour polyurethane.
7. Let it cure fully (24-48h depending on the PU you’re using).
8. Drop the whole thing in warm water. The PVA dissolves, leaving the polyurethane bush.

Limitations of v1

• Top-hat geometry only (no asymmetric flanges, no shaped crush-tube ends)
• No live 3D preview — STL opens in any slicer for visual check
• Single-piece dissolvable mould style only (no two-part reusable splits yet)

Found a problem? Have a request for v2? Comment on the related YouTube video.