The ULTMATE Sunlu-to-Bambu Spool Adapter I've taken the best ideas from the available Sunlu-to-Bambu spool adapters out there and combined them into one highly functional model.

With this adapter you get the following:

• Optional, integrated, one piece AMS Lite adapter
  • Now the AMS Lite adapter can no longer pull away from the spool when removing it from the AMS Lite
• Correctly indexed and keyed adapter
  • The other adapters assumed the spindle latching tabs were the same size (they aren't) and were evenly spaced (they aren't). I started by modeling the Sunlu spool itself in CAD, printing test pieces to verify they work correctly with both spool halves, and then built the adapters off of that model.
• High visibility sight line that greatly assists in lining up the spool with the Bambu Lab refills
• The sight line is a single piece of filament that is pressed into place after the print is complete, and does not require multi-filament support
• Tapered adapter end to make insertion into the refill's cardboard cores much easier
• Internal registration tabs that ensure the adapter can only go on one way and can't spin once in place
• Tight tolerances to ensure the adapter can press on and stay in place with a friction fit without requiring glue
• Extraction tools to assist in separating your Sunlu-to-Bambu adapter from the Sunlu spool, should you choose to do so

Installing the sight line filament

Installing the sight line filament is straightforward and requires only a section of filament and a spoon:

• Cut a section of filament to use. The section should be longer than the adapter itself, and the filament color should contrast with the adapter color
• Square off one end of the filament with diagonal cutters
• Align the filament with the sight line channel in the adapter, with the squared end against the spool notch block
• Using a spoon, grasp the spoon such that your thumb is resting on the concave portion of the spoon
• Beginning at the end of the adapter opposite of the notch block, press the convex side of the spoon against the filament, pressing into the adapter, and rock the spoon forward toward its tip. This will press a small portion of the filament into the groove
• Lift the spoon, advance 5 to 10 millimeters, and repeat pressing down and rocking forward, working your way towards the notch block
• Once the filament has been fully pressed into the groove, use your diagonal cutters to remove the excess filament from the end of the adapter
• The filament should then stay wedged into the groove without any further intervention from you. However, due to variations in dimensional accuracy from printer to printer, you may find the filament does not fit snuggly into the groove. In such cases, apply a small amount of glue along the groove before pressing the filament into place, and allow the glue to fully set before using.

Sight Line Installation Demonstration Video

Extraction Tools The adapters can be a very tight fit on the spool spindles, and difficult to take off once on. Should you decide to remove yours, simply print out the tool that corresponds with your adapter type, and follow the below videos for instructions.

In both cases, the key is to apply slow, even, downward pressure until the vacuum seal breaks and the adapter releases from the spool spindle.

Spool adapters with integrated AMS Lite adapter Extraction of spool adapter without AMS Lite adapter

Spool adapters without integrated AMS Lite adapter

• The three tool tips should press against the three downward tabs connected to the spool adapter
• If the extraction tool isn't long enough to fully release the adapter, print out the other extraction tool to place under your tool, as shown below Extraction of spool adapter without AMS Lite adapter

Quick note on Sunlu refillable spools There is quite a bit of variation among the Sunlu refillable spools. Of the four I have to test with, no two are alike and require different amounts of pressure to press on/off the adapters. Likewise, one of the spool spindles is a full three millimeters longer than the others for some reason. For cases where the spool adapter is too short, it will leave a slight gap between the spool and adapter where the adapter can't seat itself fully against the spool. I don't anticipate this will cause any issues, but if you use the adapter and have a gap, and it does cause issues for you, please reach out.

Acknowledgements

The following people and makes have contributed ideas to this model:

• Functional Print Friday - Spool Buddy - Sight line, visibility dot, tapered end
• One Maker Show - “Sunbu” Spool Adapater - Original concept
• Yesiotr - Sunlu→Bambu Refill Adapter - Integrated AMS Lite adapter