Unsupported Bridge Experiments – Ender 3 Pro Remix

Unsupported Bridge Experiments – Remix for Ender 3 Pro (Klipper, Direct Drive)

Remix of “Unsupported Bridge Experiments” by Make Wonderful Things.

About
The original model and its method worked perfectly on my Bambu Lab P2S. I wanted the same result on my modified Ender 3 Pro, so I determined the values for this printer step by step.

Setup

• Ender 3 Pro, BTT SKR Mini E3 V3, Klipper

• Creality Sprite direct drive with its stock part cooling fan, 0.4 mm nozzle

• OrcaSlicer 2.5.0-dev, 0.20 mm layer height

• Filament: rPLA by Recycling Fabrik, 220 °C

• Bridge fan 100 %, thick external bridges off, bridge density 100 %

Result for PLA on the Ender

• Bridge flow: 1.3

• External bridge speed: 10 mm/s

Process
Only one variable changed at a time, values engraved on each piece. Rounds 1–3 used the model scaled to 70 % (approx. 31 mm span), the full-size check and round 4 the original size (45 mm).

• Round 1 – Flow (speed 10): 1.0 / 1.4 / 1.8 / 2.0 → 1.4 best. Gaps between strands at 1.0, over-extrusion with ridges and blobs at the end of the bridge from 1.8.

• Round 2 – Speed (flow 1.4): 5 / 15 / 20 / 30 → 15 best. Strands tore at 30.

• Round 3 – Fine flow (speed 15): 1.3 / 1.4 / 1.5 / 1.6 → 1.3 and 1.4 best. The higher the flow, the more material piled up at the end of the bridge.

• Check – Full size (speed 15): 1.3 / 1.4 at 45 mm span → neither matched the quality of the scaled prints. 1.3 was acceptable, 1.4 showed clear gaps and sagging strands. This led to round 4.

• Round 4 – Full size fine tuning: 1.3/S10, 1.3/S15, 1.3/S15 + density 105 %, 1.3/S15 + thick bridges → 1.3/S10 clearly best. Density 105 % was worse, thick bridges failed completely.

Findings (subjective)

• Increase flow, reduce speed – the principle of the original also works on the Ender, just with slightly less flow.

• Longer bridges need more time to cool: at 31 mm, 15 mm/s was ideal; at 45 mm, 10 mm/s won.

• On my printer, thick bridges don’t work with this method.

Note
All bridge tests were done before calibrating the filament flow ratio (flow ratio at the time: 0.98). If your base flow differs, your ideal bridge flow may differ slightly too.

Transferability
The values apply to an Ender 3 Pro with direct drive. For other printers or a stock extruder, use them as a starting point and verify with your own test prints. The process above can be followed 1:1. 

This remix is also published on MakerWorld and Creality Cloud – feel free to leave a comment or make on whichever platform you use:
MakerWorld | Creality Cloud

Files

• STL of the test piece (scale it in the slicer as needed)

• OrcaSlicer 3MF with one plate per round, including the per-object settings and engraved labels

License: CC BY-NC-SA 4.0, same as the original.