Parametric TPU Bumpstop w 3 Zone Settings (kg/mm)

Press the Customize button to customize!

This OpenSCAD script generates a highly versatile bumpstop with a powerful feature: Stiffness-Based Progressive Rate. Instead of using internal infill patterns, this model controls stiffness by precisely varying the thickness of the inner and outer walls.

Features

• Stiffness-Driven Design: Set your target compression rate in kg/mm (e.g., 20kg to compress 1mm). The script uses physics-based formulas calibrated for TPU 95A to calculate the required wall thickness for both the exterior skin and the interior column.
• Smooth-Taper Wall Design: Instead of sharp steps between zones, the script generates a single, continuous internal cavity with smooth transitions. This ensures more uniform stress distribution and a professional aesthetic.
• Stress-Relief Fillets: Includes internal fillets at the top junctions where walls meet the solid cap to prevent tearing under heavy load.
• No-Infill Design: By relying on varying wall thickness instead of sparse infill, the part has much more predictable mechanical properties and is faster to print with higher structural integrity.
• Internal Air Gap: The script automatically limits wall thickness to ensure a central air cavity remains. This allows the part to vent air during compression and prevents it from blowing out the side.
• Base Support Spokes: Added radial spokes at the very bottom of the part to connect the inner column and outer wall, providing structural stability without affecting the overall compression rate.
• Fully Parametric: Adjust base diameter, top diameter, height, and top rounding.
• Rotatable Cross-Section: Toggle a 50% cutaway view with adjustable rotation to inspect the varying wall thicknesses and internal fillets before you export.
• Selectable Mounting:
  • Shaft: A simple through-hole for a central rod or shaft.
  • Bolt: A through-hole with a recessed counterbore from the top.

How To Use

• Press the customize button
• Change the parameters to your specifications
• Download as STL
• Download the sample print profile which has been highly optimized for TPU
• Delete the samples off the plate
• Import your STL to the print profile

Customization Guide

Wall Design (The Physics Bit)

• stiffness_top/middle/bottom_kg_mm: The target force (in kg) required to compress that section by 1mm.
• material_modulus_mpa: Calibrated to 30 for TPU 95A. Adjust if using softer/harder materials.
• nozzle_diameter: Used to ensure printable walls.
• min_wall_thickness: Ensures the part is never too thin to print (default 1.2mm).

Main Dimensions

• base_diameter, top_diameter, total_height: Core geometry.
• top_rounding: Radius for the smooth top edge.

Safety Disclaimer

WARNING: This part is intended for off-road or experimental use only. Bumpstops are critical safety components. A failed bumpstop can lead to mechanical damage. Use 3D-printed parts in high-load applications at your own risk.