SUNLU Filament Connector: Do you truly need something like this?

SUNLU’s new 3D printing accessory, the FC01 Filament Connector, can join various 3D materials (PLA, ABS, PETG, PCL, PA, and PC). But why do you need such a tool? Let’s find out from this review!

If you are into 3D printing, you probably know how hard it is to throw away a spool with a few meters of leftover filament. You think they will still be good at something, like testing a new 3D machine or printing small models. The SUNLU Filament Connector allows fusing together all these leftover filaments and using them to the last cm for zero waste.

The SUNLU FC01 filament jointer is also handy for making your unique multi-color filament. Using the slicer app, you can estimate the filament length for a color switch and print the model in two or three colors using your pre-join filament.

SUNLU FC01 3D Filament Jointer review

Disclosure: I received this filament joint machine as part of a product review collaboration with SUNLU. Product specs and quality may vary according to the manufacturer’s reliability, so I cannot guarantee that you will get products that perform the same as shown in my article.

In addition to various printing materials (filaments and resins), SUNLU offers a wide range of 3D printing accessories, including filament dryers, vacuum bags, and enclosures. The FC01 is the company’s and industry’s filament filament fuser tool.

The FC01 was sent out from SUNLU’s European warehouse, and I received it in less than a week. They also sent me two spools (Silver and Fuchsia) of their upgraded PLA+ 2.0 filaments. The filament connector comes in the box with a bag of PTFE splice sleeves (200 pcs of Teflon tubes) and a USB power cable. The filament fuser unit measures about 75x110x35mm and weighs 140 grams. It has a transparent “design” cover and a safety one that secures filaments during fusing. On the front panel is a 50x13mm monochrome touchscreen for easy operation.

Inside, in the unit’s center, there is a metal heating element that melts the two filament ends. On the back, a replaceable blade allows you to cut off the PTFE tube after you finish joining the two filaments.

A tiny switch detects when the filament flap is closed, and when the melting process is finished, a sound alarm warns you to remove the filaments. It has five pre-set temperature and melting time settings (PLA, PCL, ABS, PETG, and PA\PC).

Filament Connector FC01: Core features

• [Zero Waste] SUNLU Filament Connector FC01 fully utilizes leftover 3D printing filament, minimizing waste and saving costs. The fusion splicer reduces tail material waste and helps users save on new consumables. Achieve efficient printing projects with zero waste.
• [Creative DIY, Multi-Color Printing] Easily fuse filaments of the same material but different colors to create vibrant, personalized 3D prints, whether for multi-color models or gradient effects.
• [Quick and Accurate Fuse] The SUNLU FC01 rapidly heats up to 185°C in about 3 minutes, improving efficiency and saving time. Temperature accuracy within ±3°C ensures reliable and consistent operation for a stable and efficient experience.
• [Wide 3D Printing Material Compatibility] It allows up to 240°C fuse temperature and is compatible with most 3D printing materials, such as PLA, ABS, and PETG (1.75mm diameter).
• [Ultra-Safe Design] It adopts advanced temperature control and high-quality insulation materials to keep the external temperature between 50 °C and 100°C during fusion, ensuring safe and worry-free use.
• [Visual Operation] Built-in window and display screen for real-time monitoring of the fusion process. Provides real-time temperature information, ensuring users are informed of each step and the equipment’s status.

3D Filament Connector (Welder): How does it work, and how do you use it?

In summary, the filament connector’s working principle is similar to that of a fiber optic fusion splicer but without the need for ultra-high accuracy in aligning the two ends. The unit’s heart is a heating element with precise temperature control.

When you turn on the appliance, it starts to heat up to the default temperature setting -when this is reached, you will hear three beeps.

First, you must make a clean cut on the end of each of the two filaments you want to join. I recommend making angle cuts for an increased contact surface. Next, you need to insert the two ends into a Teflon tube —make sure they touch, and there is no space between them. After this, insert the tube into the SUNLU melting machine, ensuring the junction falls in the center of the heating element, and close the safety cover. It is essential to choose materials with the same melting temperature; otherwise, they will not fuse.

The fusion process starts automatically, and the FC01 will confirm when you can remove filaments. After the joint area has cooled and hardened, you can remove the tube with the built-in blade.

Lastly, perform a visual inspection for dimension imperfection or poor bonding —if something is wrong, repeat the process.

The week-long test period taught me that all the welds will be perfect no matter how many times you try. The procedure can be perfected by testing different temperature settings, but you can still be surprised that the weld will come apart during use or get stuck in the print head. Leveraging the PLA temperature from 185°C to 175°C improved the results. Also, pushing the two ends into each other when melted strengthens the bond.

I recommend printing and using this Pocket Razor Blade Tube Filament Cutter, which allows clean, precise, straight, angled cuts. Another project you should consider printing is this spool drill winder, which allows easy and fast re-spooling of your custom filament blend.

Most wet 3D filaments, including PLA, tend to break when handled, so I recommend dehydrating them before use. The FilaDryer S4 can dry four rolls simultaneously, making it a perfect option for custom-blend filaments.

Recommended temperature and time settings

The FC01 comes with presets for each time of commonly used filaments. If the joins are imperfect, you can try increasing/decreasing the temperature and adjusting the fusing time.

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Since 2014, FirstQuadcopter has reviewed, thoroughly tested, and rated hundreds of products, including drones, gimbals, power stations, action cameras, 3D printers,  and other high-tech gear to help you make better buying decisions.