Parametric Cardboard Spool Arbor Adapter (OpenSCAD) — Fits Clough42 Bearing Shaft & More

Overview

A fully parametric OpenSCAD arbor adapter for cardboard filament spools. It widens the bearing contact and adds low-profile chevron nubs so cardboard cores sit square on shafts/rollers and don’t tip off bearings. Designed around the Clough42 PolyDryer bearing shaft, but adjustable for any cardboard spool.

Why This Exists

On PolyDryer setups, some cardboard spools can rotate sideways and fall off the bearings, causing jams. 
 

This adapter:

• Centers the spool on the shaft
• Widens the support so it stays square
• Uses gentle locking nubs to protect the cardboard while preventing slip
• Stays fast to print (flange-down, no supports)

Features

• Parametric OpenSCAD: set bore, wall, depth, flange, chamfer, tolerance
• Chevron nubs: mirrored triangular bumps on the outside for light snap-fit
• Universal: works across brands (just measure core I.D.)
• Print-friendly: no supports, short print time
• Tunable fit: fit_adjust compensates for printer/material

Parameters (mm)

• id — core inner diameter (nominal)
• wall — tube wall thickness (radial)
• depth — tube height inserted into core
• flange_thick — flange thickness
• flange_over — flange radial overhang
• chamfer — small top chamfer on flange
• fit_adjust — bore compensation (+ opens the hole slightly)
• nub_count — number of chevron nubs (4–8 typical)
• nub_depth — nub protrusion beyond wall (0.4–0.7 typical)
• nub_width — tangential footprint of nub (4–6 typical)
• nub_height — nub height (1.6–2.2 typical)
• nub_z_offset — start height of nubs above flange (6–8 typical)

Suggested Presets

SUNLU cardboard core (tested)
id=49, wall=2.2, depth=12, flange_thick=2.6, flange_over=4, fit_adjust=0.3, nub_count=6, nub_depth=0.6, nub_width=4.5, nub_height=2.0, nub_z_offset=7

• Tighter grip → increase nub_depth by +0.1 or add +2 nubs
• Gentler insert → reduce nub_height to ~1.6 or nub_depth to ~0.5

Tip: If your Sunlu batch varies, measure the core I.D. with calipers and tweak id ±0.5 mm, then reprint a quick single.

Print Settings

• Orientation: flange down
• Supports: none
• Walls: 3–5 perimeters
• Infill: 20–40%
• Material: PLA or PETG (PETG preferred for durability)
• Nozzle: 0.4 mm (0.6 mm also fine)

Tuning & Fit Tips

• Too tight? Raise fit_adjust by +0.1.
• Too loose? Increase nub_depth by +0.1 or increase nub_count.
• Hard to insert? Lower nub_height to ~1.6 or widen nub_width slightly.

Inspiration

Inspired by the general idea of cardboard spool arbor adapters, but implemented from scratch in OpenSCAD as a fully parametric design focused on Clough42 PolyDryer shaft compatibility and broader multi-brand use.