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Respooling filament, refill spools and joining filament

Filaments8 min readUpdated: 10/2026

are explained briefly when you hover over or tap them.

When respooling, you wind filament from one spool onto another, for example from a cardboard spool onto a plastic spool that fits your multicolour system. The most important rule: never let go of the loose end. Tangles almost always happen because the end springs back and slips under another winding. Refills without a spool, on the other hand, go onto a reusable spool from the manufacturer, and you only cut the retaining straps once the spool is firmly closed. Filament offcuts can be joined with heat, but the joint must then be back at the normal diameter.

When respooling makes sense

  • Spool does not fit: Multicolour systems and dryers accept only certain spool dimensions (table below).
  • Cardboard spool: Some systems are not approved for cardboard spools. QIDI, for example, writes that the QIDI Box is not compatible with cardboard spools and recommends an adapter ring. Snapmaker lists more friction, cardboard dust and a greater tendency to absorb moisture as drawbacks of cardboard spools.
  • Damaged spool: A broken spool flange can make the filament unwind unevenly.
  • Filament bought without a spool: Bulk packs or refills have to go onto a spool.

Spool dimensions of some multicolour systems

SystemDiameterWidthNote
Bambu Lab AMS liteinner diameter 53 to 58 mm40 to 68 mmno further manufacturer information
Creality CFS197 to 202 mm42 to 68 mmno further manufacturer information
Creality CFS lite195 to 202 mm42 to 68 mmCreality cardboard spools compatible according to the manufacturer
Anycubic ACE 2 Pro195 to 200 mm60 to 68 mmstandard 1 kg spools
QIDI Box195 to 202 mm50 to 72 mmno cardboard spools without an adapter ring

As of: manufacturer information in October 2026. For other devices and newer models, the manufacturer’s instructions apply. Which filaments a system can process in general is covered in Multicolour printing.

Respooling by hand

You need the full spool, an empty spool, a rod on which both can turn freely (a broomstick between two chairs will do in a pinch), and a filament clip or tape. Snapmaker describes the procedure like this:

  1. Mount both spools so that both turn easily. The filament should come off the full spool in the same direction in which it goes onto the empty spool, for example both from the top.
  2. Transfer the end: Release the end from the full spool without letting go of it, and thread it through one of the holes in the core of the empty spool.
  3. Winding: Turn the empty spool. With your other hand, hold the filament lightly and evenly taut.
  4. Guiding: Guide the filament back and forth across the width of the spool as you go, so that even layers form.
  5. Securing the end: At the end, hold on to the end and immediately clamp it in the flange of the new spool.

A neatly wound spool unwinds more evenly. According to Snapmaker, slightly untidy layers are not a problem as long as nothing is tangled. A smooth winding is less likely to snag, though.

Respooling with a spool winder

Rewinding a whole 1 kg spool by hand takes a while. It is quicker with some help:

  • Cordless drill: The empty spool sits on an axle that is clamped into the drill.
  • Printed spool winder: There are many models on MakerWorld, Printables and other platforms, often with ball bearings and a guide for the filament.

Here too: turn slowly and evenly, guide the filament lightly taut and never let go of the end. Snapmaker explicitly warns against winding too fast.

Is the spool already tangled?

You cannot get a real knot out by winding on. Snapmaker recommends unwinding a few dozen metres by hand and letting it fall loosely on the floor until you can see the spot where one winding lies under another. Free that spot, wind the loose filament carefully onto the new spool and then carry on as normal.

Refills: using filament without a spool

Refills are rolls of filament without their own spool. They are placed on a reusable spool. Important: a refill belongs on a spool that the manufacturer approves for it. The cores differ from brand to brand.

Bambu Lab Reusable Spool

According to the Bambu Lab Wiki, there are two versions of the reusable spool:

VersionMaterialTemperature limitApproved filaments
Low TempABSup to 70 °CPLA, PETG
High TempABS+PCup to 90 °CPLA, PETG, ABS, ASA, PA6-GF, ABS-GF, PAHT-CF, PET-CF, PA6-CF, PC, TPU

The temperature limit matters if you dry the filament on the spool.

This is how you fit a refill:

  1. Remove the packaging. The transparent retaining strap stays on. With 250 g refills, the cardboard core stays in as well.
  2. Unscrew the spool anticlockwise. The wide half is on the left, the narrow one on the right.
  3. Align the notch in the refill’s cardboard core with the clip on the wide half, press the refill on firmly, fit the narrow half and turn it clockwise until it clicks quietly.
  4. Only now open the retaining strap at the filament end, push the end into the round hole of the spool and then remove the rest of the strap.
  5. If the filament sticks out to the side, press the windings against the spool by hand. This stops windings from coming loose and tangling.
  6. Stick the label of the new filament onto the spool.

SUNLU offers refills that, according to the manufacturer, fit only its own third-generation reusable spool and the Bambu Lab spool.

Prusament Refill

In its knowledge base, Prusa describes two variants. With the older 1 kg refills, the black side parts of an empty Prusament spool are pulled off the cardboard core and pressed onto the refill. If the parts are hard to remove, Prusa recommends soaking the spool, after which the cardboard core gives way immediately. You only cut the orange strap once the spool is firmly assembled, preferably with scissors rather than a knife. Grey Prusament spools for engineering materials are glued and cannot be taken apart this way. For the newer 900 g refills without a cardboard core, Prusa has its own guide.

The most common mistakes with refills

  • Retaining straps cut too early: The windings then spring open and the roll tangles. Bambu Lab and Prusa both say explicitly: cut the strap only once the spool is closed.
  • Spool not properly latched: A half-closed spool can rub in the multicolour system.
  • Wrong spool: Refills from different manufacturers have different cores. Check beforehand whether the manufacturer approves the combination.

Joining filament

Offcuts from different spools can be fused into one longer strand. This saves offcuts or allows simple colour gradients without a multicolour system.

The methods

MethodHow it worksThings to note
PTFE tube and heatCut both ends straight, push them into a short piece of PTFE tube from both sides, heat the middle with hot air or a lighter and press the ends togetherThe tube holds the diameter. A printed holder with a spring makes this easier.
Aluminium foil and soldering ironCut the ends straight, wrap them tightly in aluminium foil, heat with the soldering iron, let cool in the foilAccording to Tom’s Hardware, it can easily smear
Filament welderThe device heats to an adjustable temperature, and the ends are fused in itExample SUNLU FC01: heats to 185 °C in about 3 minutes, maximum 240 °C, for PLA, ABS and PETG at 1.75 mm

How to recognise a good joint

Mosaic, maker of the Palette system, which welds filament together automatically, names three checks:

  1. The joint holds when being pulled into the extruder.
  2. It can be bent and breaks only after being bent back and forth several times.
  3. The diameter is about 1.75 mm, plus or minus 0.10 mm. It is best to measure with callipers at several points.

If the spot is thicker, carefully sand or cut off the bead until it fits through the tube again.

Limits

  • Same material: SUNLU explicitly advertises its device for filaments of the same material in different colours. Different materials such as PLA and PETG can also be joined by Mosaic’s Palette system, but it needs its own settings for this, sometimes even depending on the direction of the joint.
  • Dry filament: SUNLU recommends drying filament before joining it so that the joint holds.
  • Practice: The first attempts rarely succeed. Test the joint before you send it into a long print.
  • Brittle ends: If the filament already breaks when bent, even a good joint does not help much. More on this in Filament breaks or becomes brittle.

Next: Drying and storing filament and Multicolour printing.

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