Bambu Lab’s Automatic Material System and the Importance of Humidity Control

The Bambu Lab Automatic Material System (AMS) revolutionizes 3D printing by streamlining filament management for multi-material and multi-color projects. Designed to work seamlessly with Bambu Lab’s advanced 3D printers, the AMS automates filament swapping and ensures precise material handling, eliminating manual intervention during complex prints. With its smart storage and compatibility with various filament types, it enhances productivity and reduces the risk of errors, making it an essential tool for professionals and hobbyists alike.

AMS Technical Specifications

The AMS unit measures 280mm × 224mm × 224mm and can hold up to four 1kg spools of filament simultaneously. It’s compatible with:

• Filament diameter: 1.75mm ± 0.05mm
• Spool dimensions: Up to 200mm diameter, 68mm width
• Operating temperature: 10-40°C
• Storage humidity: Target <20% RH
• Power consumption: 36W maximum
• Weight: 3.2kg (empty)

A key feature of the AMS is its focus on humidity control, a critical factor in maintaining filament quality. It does this by utilizing an air-tight seal and with the help of desiccant material, it absorbs moisture to keep the moisture away from filament.

A Humidity Sensor also detects the humidity inside the AMS and provides information to the user when the humidity is higher or the desiccant may need to be replaced. The system uses a three-level indicator:

• Level 1 (Green): <10% RH - Optimal
• Level 2 (Yellow): 10-20% RH - Acceptable
• Level 3 (Red): >20% RH - Action needed

Why Minimize Humidity?

Humidity can wreak havoc on filament properties. When filaments absorb moisture, several issues can arise during printing. Moisture-laden filaments can lead to poor adhesion between layers, causing warping or misshaping of the final print. Additionally, when moisture in the filament is heated during the printing process, it turns into steam, creating tiny bubbles or voids in the extruded material, which severely affects the strength and aesthetics of the print.

Humidity Thresholds by Filament Type

Different filaments have varying sensitivities to moisture:

The Science Behind Humidity Impact

At a microscopic level, moisture impacts the filament’s viscosity during the melting process. This alteration can lead to inconsistent extrusion rates, which are critical for precision in 3D printing. Filaments like PLA, PETG, and especially hygroscopic materials like Nylon or TPU can absorb moisture from the air, leading to compromised prints.

The Chemistry of Moisture Absorption

When thermoplastic filaments absorb moisture, water molecules integrate into the polymer chains through hydrogen bonding. During extrusion at high temperatures (180-250°C), this absorbed water rapidly converts to steam, causing:

1. Hydrolysis: Breaking of polymer chains, reducing material strength
2. Foaming: Steam bubbles creating voids in the extruded material
3. Surface defects: Rough, matte finish instead of smooth surfaces
4. Dimensional instability: Unpredictable expansion affecting tolerances

Understanding Desiccants: A Deep Dive

Not all desiccants are created equal. Understanding their properties helps in making informed decisions:

Desiccant Comparison Table

How Desiccants Work

Calcium Chloride (CaCl₂): Works through deliquescence - it absorbs so much moisture that it dissolves into a liquid brine. This process is irreversible, making it non-rechargeable. Chemical reaction:

CaCl₂(s) + 2H₂O(g) → CaCl₂·2H₂O(aq)

Silica Gel: Uses adsorption - water molecules stick to the surface of the silica particles. This process is reversible through heating, making it rechargeable. The indicating varieties contain cobalt chloride (blue) or methyl violet (orange) that changes color when saturated.

Improvements: The DryPod Solution

Although the AMS system performs well in maintaining a consistent and steady humidity level, there is still room for improvement to optimize its performance. While it effectively handles standard conditions, certain scenarios or environmental factors may expose limitations in its ability to maintain ideal humidity levels.

One of the most significant issues I’ve noticed is that the desiccant used (and sold by Bambu) isn’t rechargeable. To be frank, it’s not particularly effective either. Each AMS unit relies on two desiccant packs, which, in my experience, only last about a month—even in a relatively dry environment. And did I mention they’re not rechargeable? This is because the desiccant is made from calcium chloride (CaCl₂), which inherently lacks the ability to be regenerated for repeated use.

Calcium chloride is an inorganic compound – a salt with the chemical formula CaCl₂. It is white flakes or pellets at room temperature, and is highly soluble in water.

Enter AMS DryPods designed by mcmaven. With over 28k downloads it’s one of the best solutions out there.

Complete DryPod Installation Guide

What You’ll Need

Materials:

• DryPod STL files from MakerWorld
• 250-500g of silica gel beads (2-4mm size recommended)
• Optional: Hygrometer (see supported models below)
• Optional: Fine mesh or fabric for desiccant containment

Tools:

• 3D printer with minimum 200×200mm build plate
• Phillips screwdriver
• Small funnel or scoop

Printing the DryPods

Recommended Print Settings:

• Layer Height: 0.2mm
• Infill: 20-30% (Gyroid or Grid)
• Wall Loops: 3
• Support: None needed
• Filament: PETG or ABS (heat resistant)
• Print Time: ~8-12 hours total

Components to Print:

1. Wide DryPod containers (2-4 units)
2. Narrow DryPod containers (optional, 2-4 units)
3. Desiccant trays (4-8 units)
4. Hygrometer holders (if using)

Step-by-Step Installation

Hygrometer Options

These DryPods are 3d printable and contain printable desiccant trays as well as desiccant containers that slide between the first stage feeder motors. The containers come in several variations to include Wide DryPod options that can hold hygrometers:

• Bambu Round Hygrometer: 42mm diameter × 14mm deep body with 46mm diameter bezel. Available with vertical or 30-degree tabs, with full or shallow mounting holes.
• Bambu Rectangular Hygrometer: 45×26×15mm body with 48×29mm bezel. Good for tighter spaces.
• Xiaomi Bluetooth Thermometer: 43×43×12.5mm body. Offers wireless monitoring via smartphone app.
• Generic Mini Hygrometers: Various sizes available on Amazon/AliExpress, typically 35-45mm diameter.

Cost Analysis: Making the Switch

Initial Investment

• DryPod printing: ~$5-10 in filament
• Silica gel (500g): $15-25
• Hygrometer: $10-30
• Total setup cost: $30-65

Ongoing Costs Comparison

Bambu OEM Desiccant:

• Cost per pack: $8-12
• Replacement frequency: Monthly
• Annual cost: $96-144

DryPod with Silica Gel:

• Electricity for recharging: ~$2/year
• Silica gel replacement: Every 2-3 years ($20)
• Annual cost: ~$8-10

ROI Timeline: The DryPod system pays for itself in 3-6 months, depending on humidity levels and usage.

Performance Data and Testing

Real-World Testing Results

I conducted a 6-month test comparing different desiccant solutions:

Print Quality Impact

Testing with hygroscopic PETG filament showed dramatic differences:

• Without humidity control: Severe stringing, poor layer adhesion, matte finish
• With Bambu desiccant: Improved but inconsistent after 3 weeks
• With DryPods: Consistent high-quality prints throughout test period

Troubleshooting Guide

Common Issues and Solutions

Problem: Humidity not dropping below 20%

• Check desiccant saturation (color indicators)
• Verify AMS seal integrity
• Consider adding more DryPods
• Check ambient room humidity

Problem: Desiccant beads spilling

• Use mesh covers on trays
• Don’t overfill (80% maximum)
• Check for cracks in printed parts
• Consider larger bead size (3-4mm)

Problem: Hygrometer reading seems incorrect

• Calibrate using salt test method
• Ensure proper airflow around sensor
• Check battery level
• Compare with external hygrometer

Problem: Filament still showing moisture issues

• Pre-dry filament before storage
• Check specific material requirements
• Increase desiccant quantity
• Consider active drying solution

Signs Your Filament Has Moisture Damage

1. Visual indicators:
   • Bubbling or foaming during extrusion
   • Steam or vapor from nozzle
   • Rough, matte surface finish
   • Visible stringing between parts
2. Print defects:
   • Poor layer adhesion
   • Warping or curling
   • Dimensional inaccuracy
   • Brittle or weak parts
3. Sound indicators:
   • Popping or crackling during printing
   • Inconsistent extrusion sounds

Maintenance Schedule

Daily

• Check humidity indicator levels
• Visual inspection for any issues

Weekly

• Verify hygrometer readings
• Check for desiccant color changes

Monthly

• Inspect desiccant saturation level
• Clean any dust from containers
• Verify seal integrity

Quarterly

• Recharge silica gel if needed
• Deep clean AMS interior
• Replace worn seals
• Calibrate hygrometers

Annually

• Replace silica gel if effectiveness decreases
• Print replacement parts if showing wear
• Full system inspection

Recharging Silica Gel

Oven Method

1. Spread saturated silica gel on baking sheet
2. Set oven to 200°F (93°C)
3. Bake for 2-3 hours
4. Stir every 30 minutes
5. Cool before refilling containers

Microwave Method

1. Use microwave-safe container
2. Heat in 30-second intervals
3. Stir between intervals
4. Continue until color returns
5. Total time: 5-10 minutes

Food Dehydrator Method

1. Set to 135°F (57°C)
2. Run for 4-6 hours
3. Most gentle method
4. Good for indicator gel

Alternative Humidity Control Solutions

Commercial Options

Sunlu FilaDryer S2:

• Active heating and circulation
• Can dry while printing
• Price: $40-60
• Good for emergency drying

PolyBox Edition II:

• Complete storage solution
• Built-in humidity control
• Price: $150-200
• Professional grade

EIBOS Cyclopes:

• Inline filament dryer
• Works during printing
• Price: $80-100
• No storage capability

DIY Alternatives

Food Container Method:

• Airtight food containers
• EVA foam for spool holders
• Loose silica gel packets
• Cost: $20-30
• Basic but effective

Modified Pelican Case:

• Waterproof case
• Custom spool holders
• Built-in hygrometer
• Cost: $50-100
• Portable solution

Environmental Impact

Sustainability Comparison

Disposable (CaCl₂):

• Single-use only
• Becomes liquid waste
• Requires special disposal
• High carbon footprint
• 12-24 packets per year

Rechargeable (Silica Gel):

• 500+ recharge cycles
• Minimal waste
• Standard disposal after years
• Low carbon footprint
• One purchase lasts years

Proper Disposal

Calcium Chloride:

• Cannot go in regular trash when liquid
• Neutralize with baking soda first
• Check local hazardous waste rules
• Can damage plumbing if poured down drain

Silica Gel:

• Non-toxic when exhausted
• Can go in regular trash
• Consider garden use (soil amendment)
• Recycle plastic containers

Community Feedback and Case Studies

User Testimonials

John from Florida (95% humidity): “Living in Florida, humidity is our biggest enemy. The DryPods dropped my AMS humidity from 65% to 15% in just 4 hours. Print quality improvement was immediate and dramatic.”

Sarah from Seattle: “I was skeptical about 3D printing my own solution, but the cost savings are incredible. I’ve saved over $200 in the first year alone.”

Mike from Arizona: “Even in the desert, monsoon season wreaks havoc. DryPods keep my exotic filaments pristine year-round.”

Professional Use Cases

Engineering Firm: Implemented DryPods across 10 AMS units, reporting 75% reduction in failed prints due to moisture issues. Annual savings: $3,000+

School Makerspace: Students maintain the system as part of learning routine. Teaches both 3D printing and material science concepts.

Production Environment: Small batch manufacturer uses modified DryPods with data logging for quality control documentation.

Advanced Modifications

Smart Monitoring

ESP32 Integration:

• WiFi-enabled monitoring
• Push notifications for high humidity
• Data logging to spreadsheet
• Integration with OctoPrint
• Cost: ~$15 additional

Home Assistant Integration:

• Real-time dashboard
• Automated alerts
• Historical tracking
• Multi-printer monitoring

Extreme Environment Mods

High Humidity (>70% ambient):

• Double DryPod configuration
• Active air circulation fan
• Molecular sieve upgrade
• Sealed cable passages

Temperature Fluctuations:

• Insulation additions
• Thermal mass buffers
• Active heating element
• PID temperature control

Future Developments

The 3D printing community continues to innovate:

• Version 2 DryPods: Improved airflow design
• Universal Fit: Adapters for other printer brands
• Active Systems: Integrated heating/circulation
• IoT Features: Cloud monitoring and alerts

Stefan from CNC Kitchen has created an excellent and detailed video exploring the different types of desiccants, their pros and cons, and various methods for drying them. While he focuses heavily on filament bags, the drying techniques he explains are equally applicable to loose desiccant. It’s an insightful resource for anyone looking to optimize moisture control.

Conclusion

The integration of systems like the Bambu Lab AMS with advanced humidity controls such as DryPods using rechargeable desiccant highlights the growing sophistication of 3D printing technology. By tackling the critical issue of humidity’s impact on filaments, these solutions are setting a new standard for reliability and efficiency in 3D printing.

The financial benefits are clear: a one-time investment of $30-65 replaces an annual expense of $100-150, while delivering superior performance. The environmental impact is equally significant, reducing waste by over 90% compared to disposable solutions.

These innovations empower both enthusiasts and professionals to achieve higher-quality results with greater consistency. Whether you’re printing engineering prototypes in humid Florida or artistic pieces in dry Arizona, proper humidity control is no longer optional—it’s essential.

As the industry continues to evolve, systems like these are likely to become standard equipment in the world of additive manufacturing. The question isn’t whether you need humidity control, but rather how quickly you can implement it to start seeing the benefits in your own prints.

Stuff I use

• Hygrometer - Mini Digital
• Dry & Dry Premium Orange Indicating Silica Gel Beads
• Fine Mesh Bags for Desiccant
• Bluetooth Hygrometer with App

Additional Resources

• AMS DryPods on MakerWorld
• Bambu Lab AMS Documentation
• Filament Humidity Calculator
• CNC Kitchen Desiccant Guide

Have questions or suggestions? Feel free to reach out in the comments below or join the discussion on the Bambu Lab forums!