Retraction Tower

Retraction Tower

1 Explanation

Bambu Lab includes its own calibration models, but many users are unaware of their location or usage. This provides a brief explanation. My machines utilize near-field extrusion; therefore, I lack experience with far-field extrusion, and this information is for reference only.

When testing with materials like PLA or ABS, which are less prone to stringing, you might find that any retraction length works effectively, with no stringing throughout the entire tower. If this occurs, set the retraction distance in your filament settings to any value between 0.2mm and 0.4mm. PETG, however, is significantly more prone to stringing; thus, this calibration is particularly beneficial for PETG users.

The retraction tower features varying heights corresponding to different retraction distances during printing. A small protrusion marks each increment. After printing, carefully examine the results to determine the optimal retraction distance. This is typically the layer exhibiting the least stringing. If multiple layers show equally minimal stringing, select the layer with the shortest retraction. The optimal retraction distance is calculated as: Starting value + Step size × Number of protrusions on the layer with the least stringing. The model I provide uses 0.1 × Number of protrusions on the layer with the least stringing. Then, input this value into Filament Settings—Parameter Override—Retraction Distance.

For customizing retraction length, see below:

2 Customizing Retraction Length

1. Click the settings icon (red area in the image below)
2. 

3. Select the printer shown (theoretically, any non-Bambu Lab printer should work), then click OK

   

4. A Test button will appear at the top of the interface; click it.
5. 
6. Click Calibration—Retraction Test—Adjust Parameters in the upper left corner.
7. 
8. Switch to your printer and click Use Modified Value.
9. Proceed with normal printing.

3 Other Tests

Recommended test order:

1. First Layer Test (if stationary, testing once suffices)First Layer Test from aurora - MakerWorld
2. Temperature Tower (generally tested upon filament arrival; recommended when changing filament brands; minimal impact otherwise)Temperature Tower from aurora - MakerWorld
3. Pressure Test/Dynamic Flow Calibration (unnecessary if Bambu Lab's dynamic flow calibration is used; recommended for Klipper users; generally minimal impact between filaments; I usually test once and disregard further tests)
4. Retraction Test (generally tested upon filament arrival; recommended when changing filament brands; minimal impact otherwise; negligible impact with PLA; recommended for PETG if significant stringing occurs and is not due to moisture absorption)Retraction Tower from aurora - MakerWorld
5. Hole Compensation Calibration & Filament Shrinkage Rate (different brands have varying shrinkage rates; recommended testing when changing filaments if time allows; Bambu Lab's hole dimensions tested well; primarily for DIY machine calibration. However, if required, strongly recommended)
6. Maximum Flow Rate Test (unnecessary without high-speed printing. Its purpose is to determine the maximum volumetric flow rate of the filament, but Bambu Lab's parameters are generally conservative, so using default parameters suffices)
7. Resonance Compensation Test (recommended for Klipper users who wish to avoid installing an accelerometer; significantly improves print quality; my Bambu Lab machine has built-in resonance compensation, so testing is unnecessary)

Models will be uploaded sequentially in the future