Yes, you can join two rolls of filament, but the joint needs to be strong enough to feed through your printer without breaking

The most reliable way to connect two rolls is the splice-and-tape method: you cut both filament ends at a sharp angle, overlap them slightly, and wrap the joint tightly with a high-temperature tape like Kapton or PTFE (plumber's) tape. This creates a tapered transition that can pass through your printer's extruder without jamming. The joint will be slightly thicker than the filament itself, but that thickness tapers gradually enough that most printers handle it without complaint.

The alternative is a mechanical connector — a small tube or coupling designed to grip both filament ends. These work, but they create a hard step in diameter that can catch in the extruder or cause extrusion problems. Most people find tape more forgiving.

Neither method is perfect. The joint is a weak point, and if your printer's extruder is worn or your tension is too high, the filament can snap at the splice. You will also see a slight quality change in your print where the joint passes through the nozzle — usually a thin line or slight color shift if you are joining different colors. Plan your print so the joint happens in a less visible area, or use the joined filament for test prints and supports rather than final parts.

Key Takeaways

  • The splice-and-tape method — cutting both ends at an angle, overlapping them, and wrapping with high-temperature tape — is the most common way to join filament.
  • The joint creates a weak point that can break under high extruder tension, so monitor your first print after joining.
  • Your print will show a visible line or color shift where the joint passes through the nozzle, so position the joint in a hidden area.
  • Mechanical connectors exist but often cause jamming because they create a hard step in diameter instead of a gradual taper.

The Splice-and-Tape Method Step by Step

Start by cutting both filament ends at a 45-degree angle using a sharp utility knife or filament cutter. A clean, angled cut is critical — a rough or perpendicular cut will not overlap smoothly and the joint will be weak. Hold the filament steady and make one smooth stroke rather than sawing back and forth.

Overlap the two angled ends so they form a cone shape, with the thinner parts of the cuts pointing outward. The overlap should be about half an inch. You want the filament to taper gradually from the original diameter down to the joint and back out again, not jump abruptly from thin to thick.

Wrap the overlapped section tightly with Kapton tape or PTFE plumber's tape, starting at one end and spiraling around the filament. Make at least three full wraps, pulling the tape snug as you go. The tape holds the two pieces together and creates a smooth surface for the extruder to grip. Kapton tape handles heat better than regular masking tape, so it is worth using if you have it — regular tape can leave residue inside your extruder.

Let the joint sit for a few minutes before loading it into your printer. The tape needs time to set and grip the filament firmly.

What Happens When the Joint Reaches Your Extruder

As the filament feeds through your printer, the tapered joint will compress slightly as it enters the extruder's grip. If your tape is tight and your overlap is smooth, the joint will feed through without stopping. The extruder will push the filament forward just as it does with any other section.

The moment the joint enters the hot end, you may see a brief pause or slight extrusion change as the slightly thicker section passes through the nozzle. This usually shows up as a thin line in your print or a momentary color shift if you joined two different colors. This is normal and not a sign of failure.

The real risk is if your extruder tension is too tight or the filament is old and brittle. The joint is weaker than the rest of the filament, so high pressure can snap it. If your printer has adjustable extruder tension, back it off slightly before loading a joined filament. If the filament breaks at the joint, you will need to open the extruder, remove the broken piece, and reload.

Using Mechanical Connectors Instead

Some people use small metal or plastic tubes that grip both filament ends — essentially a coupling that holds them together. These are faster than taping and create a very solid joint mechanically.

The problem is that a connector creates a hard step in diameter. Your filament goes from normal thickness to the thickness of the connector, then back to normal. This step can catch on the extruder's teeth or jam in the hot end, especially if your printer has a Bowden tube (a tube that guides filament from the extruder to the nozzle). The tapered joint from taping is more forgiving because there is no sudden change in size.

If you do use a connector, test it on a short print first and watch the printer carefully as the joint approaches the extruder. If you hear grinding or see the filament stop feeding, stop the print immediately and remove the connector.

Planning Your Print Around the Joint

Before you load your joined filament, think about where the joint will be in your print. A typical roll of filament is 1 kilogram, which translates to roughly 300 to 400 meters of filament depending on the material and diameter. A small print might use 10 to 50 grams, so the joint could appear anywhere in your print depending on where you are in the roll.

If you are printing something where appearance matters, you have a few options. You can print a test object or a support structure first to use up filament and push the joint further into the roll. You can print the object in a color or orientation where the thin line from the joint is less visible. Or you can simply accept that this print will have a visible line and use it for a functional part or a test print.

If you are joining two different colors intentionally, position the joint so the color change happens in a less visible area — the back of an object, the bottom, or an internal support structure.

When Joining Filament Is Not Worth It

Joining filament makes sense when you have a small amount left on one roll and a large print that needs more than that amount. It saves you from buying a new roll for the last 50 grams of material.

It does not make sense if you are only a few grams short. The joint is a weak point and a potential failure, so it is worth avoiding if you can. If your print needs 100 grams and you have 95 grams left, the risk of the joint breaking mid-print is higher than the cost of a small amount of wasted filament.

It also does not make sense if you are printing something critical or high-precision. A joint in a structural part or a part that needs to be perfect is a liability. Save joined filament for test prints, supports, and functional parts where a thin line or slight quality change does not matter.

Frequently Asked Questions

Will the joint clog my nozzle?

Usually not, as long as your overlap is smooth and your tape is tight. The joint is slightly thicker, but the taper allows it to pass through without jamming. If your nozzle is already partially clogged or your extruder tension is very high, the joint could trigger a clog, but this is rare.

Can I join filament while a print is running?

No. You must stop the printer, open the extruder, remove the old filament, and load the new one. Trying to push a joint through the extruder while the printer is printing will cause the filament to snap or jam. Some printers have a filament-change feature that pauses the print and retracts the filament automatically, which makes the process easier.

Does the joint work with all filament types?

The method works with PLA, PETG, ABS, and most common materials. The tape needs to handle the temperature of your hot end, so Kapton tape is safer than regular tape for high-temperature materials like ABS. Flexible filaments like TPU are harder to tape because they compress under pressure, so the joint may not hold as well.

What if the joint breaks inside my extruder?

You will need to open the extruder, remove the broken filament piece, and reload. Some printers make this easier than others — check your printer's manual for the extruder access procedure. If filament breaks frequently at the joint, your extruder tension is too high or your filament is old and brittle.

Can I use super glue or epoxy instead of tape?

Adhesives do not work well because they harden the filament and create a brittle joint that snaps easily. Tape is flexible enough to move with the filament as it feeds through the extruder, which is why it is more reliable.