Improved filament feeding system using smaller spools

I used to keep almost empty 1 kg spools with original boxes. Unfortunately, they take too much storage space. When its time to use them, the usual feeding process is not as reliable for smaller prints. 

If you have tried to load remaining filament in smaller custom spool, you most likely have noticed the filament is behaving like a spring. The spool will unroll and there is very good chance your filament will tangle or unwind during printing. I don't like to waste filament especially when I am often making test and printing small parts.

I designed a complete reliable system that will solve this problem and improve filament feeding. The idea is to use two easy to build spring plungers. You can rotate plungers to adjust the side force. The ball spring plunger move between the spool circular grooves and prevent spool motion. Spool rotate only when motor extruder is active.

Features:

• Not too many parts to print.
• 110 mm Spool diameter.
• Spool capacity is approximately 100 gr of filament.
• No left and right hand for adapter housing and spool.
• Spring used for plungers are easy to find, 4,3 mm dia. x 20 mm long (standard pen)
• Quick mounting and removal by rotating Locking Pins 90 degrees.
• Can be use on M3KS with or without Enclosure Unit.
• Handy removable Spool Labels for easy material identification.

Print Settings

PLA filament for all parts. Infill 15%. Use raft only on Plunger Balls. 

Reduce printing speed for Labels and Plunger Balls.

Printing height to 0,15 mm (Quality) for Adapter Housing and Plunger Housing to improve thread details.

Bill Of Materials

 Quantity           Name                           Note

        2                Half Spool               110 mm Dia. 

        4                Locking Pin             To hold Spool Adapters together

        1                 Spool Label PLA     Filament identification

        1                 Spool Label PETG  Filament identification

        4                Spool Adapter        To hold Spool and Plungers                 

        2                Plunger Housing    M12 Diameter

        2                Plunger Cover         With groove for flat screwdriver

        2                Plunger Ball             6,4  mm Dia.

        2                Spring                      4,3 mm Dia. x 20 mm long ( from pen)

Spool Assembly

Align small tab with square recess and glue both halves together. (CA glue)

Press chosen Spool Label pegs into circular spool holes for filament identification.

When loading, end filament must be inserted in provided spool hole.

Assembling Spring Plungers

Assembling Spool Adapters

Clean threads with 12 Dia. mm tap.

Only one thread hole of Spring Plungers is used. This way, there is no need to have a left and right hand adapter. The flange and ball end plungers are on spool side.

You may have to file or sand a bit the two rectangular openings for final adjustment. It should be tight to make sure the Locking Pins heads stay on Spool Adapters.

Tips: Plunger Housing should easily screwed by hand half way.  If not, use plastics lubricant such PL-100 from PROLAB for easy assembling. You could also reduce Plunger Housing print scale by 1 or 2%. 

Warning: Do not overtight the Spring Plunger because you may damage your printer. You only need a gentle hold to prevent spool movement.  Start with a small clearance and rotate plunger ¼ turn increments.

Installing the Feeding System on PRUSA Enclosure.

As shown on Enclosure assembling instructions, the enclosure is using the existing PRUSA side arm.

The Improved filament feeding system can be installed on T spool holder or spool holder mounted inside the Enclosure ( left or right version). 

 Attached are two STEP files in case you want to  modify Spool Adapter to suit your own side arm or print your own Spool Labels.  :-)