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Practical guide

How to glue 3D printed parts: which glue to use for each filament

Sooner or later you'll need to glue something: a part that broke, a piece that snapped while removing supports, or a model too big for your bed that you had to cut into pieces. What works depends mostly on the material: the super glue that's perfect for PLA is useless on nylon, and the acetone that welds ABS can wreck other parts. Here's what to use with each filament, how to prep the surfaces and the mistakes that ruin a joint.

Quick answer: which glue for which material

PLA
First choice: Cyanoacrylate (super glue)
Alternatives: Epoxy for large or loose-fitting parts; plumber's cement; PLA-specific solvent adhesives
Avoid: Acetone baths (the part gets destroyed)
PETG
First choice: Cyanoacrylate
Alternatives: Epoxy; PET/PETG-specific solvent adhesives
Avoid: Plumber's cement (not compatible)
ABS / ASA
First choice: Acetone: dissolves the surface and "welds" the parts
Alternatives: Cyanoacrylate; plumber's cement (with ABS)
TPU and flexibles
First choice: An adhesive that stays flexible (check the label)
Avoid: Epoxy: it cures rigid and won't move with the material
Nylon
First choice: Screws, clips or snap fits
Avoid: Adhesives in general (poor bond)
Plastic to metal
First choice: Epoxy (ideally metal-filled)

The three kinds of glue you'll actually use

Cyanoacrylate (super glue)

According to Loctite, super glue is the best option for prints made of rigid plastics such as ABS, PLA and PETG. It bonds in seconds, barely leaves a seam and needs no mixing. Two formats are worth knowing: the brush-on liquid, for invisible seams, and slower-setting versions that let you reposition the part before it grabs. Gels are handy for small parts or ones you can't clamp, although Polymaker warns they don't work on nylon and can fail under sustained stress.

Two-part epoxy

Loctite sums it up: epoxy bonds almost anything and fills small gaps, but it creates rigid joints, so it's a poor choice for flexible materials. It's the option for large parts, loose-fitting joints and anything that will carry load; Polymaker mentions epoxies whose bond is stronger than the layer adhesion of many printed materials. The trade-off is time: mix, clamp and wait (minutes to 24 hours depending on the product). Check the label to make sure it bonds the plastic you're using, since many epoxies are formulated for specific jobs. For plastic-to-metal joints, Polymaker recommends a steel-reinforced epoxy.

Solvents: chemical "welding"

A solvent softens the surface of both parts and, as it evaporates, they fuse into one. It's the classic technique for ABS and ASA, which dissolve in acetone: the same principle as the acetone vapour smoothing Prusa explains. Polymaker sells adhesives of this kind formulated per material (PLA, ABS/ASA and PET), and notes the PET one works particularly well on PETG, which is traditionally hard to bond.

The catch with PLA: Prusa found its Prusament PLA glues well with acetone, "like a superglue", but PLA doesn't dissolve in it and a long bath ended up destroying the test parts. If you want to try it, test on a scrap of the same filament first. And don't consider solvents like dichloromethane or chloroform: Prusa points out they're dangerous and only sold with a special permit.

Prep the parts before gluing

Half the joints that fail do so because of prep, not the glue. The steps Loctite and Polymaker recommend:

  1. Dry-fit first. The surfaces need to seat well against each other. Remove any support remnants, strings or the usual first-layer lip beforehand.
  2. Clean grease and dirt off both faces: any residue or particles stop the glue from gripping properly.
  3. Match the texture to the glue. Some grip better on rough surfaces and others, like cements, need flat, smooth ones. The label tells you; Polymaker considers sanding and cleaning essential for every adhesive.
  4. Prepare the glue. Mix epoxy in the ratio the maker specifies, right before use.

Step by step

  1. Apply the amount the product specifies, on one or both faces as instructed. Respect the amount: excess squeezes out of the seam and has to be cleaned up.
  2. Join and hold by hand or with clamps until it sets. Super glue needs little time; with epoxy, keep the part clamped for the whole cure.
  3. Wipe off any squeeze-out before it hardens, using the solvent the maker recommends. Once cured, excess can usually be trimmed with a blade.
  4. Don't load it until the glue has reached full strength.

One warning from Loctite: polyurethane glue or a hot glue gun also work, but they leave 2-3 mm seams that show.

Gluing a split model: align first

When the model is bigger than your bed and you've split it, the problem is less about strength than alignment: the glue acts as a lubricant right when you press and the parts slide. The STL cutter adds matching alignment holes on each face of the cut: push short bits of filament in as dowels, bring the parts together and they stay locked in place while the adhesive sets. We cover it in detail in how to cut an STL that's too big for your printer.

Safety

Frequently asked questions

What's the best glue for PLA?
Cyanoacrylate (super glue) is the go-to for rigid plastics like PLA: it bonds in seconds and leaves a thin seam. For large parts, gaps or joints that need to carry load, a two-part epoxy gives more working time and fills irregularities.
Can you glue PETG with super glue?
Yes, Loctite recommends super glue for PETG too. Still, Polymaker describes it as a material that's traditionally difficult to bond, so prep the surfaces well (clean, good fit) and consider epoxy for load-bearing joints. Avoid plumber's cement: it isn't compatible with PETG.
Does acetone glue PLA?
With ABS and ASA, acetone is the classic route because it dissolves them. With PLA it depends on the brand: Prusa found its Prusament PLA glues well with acetone, but also that PLA doesn't dissolve in it and that a long bath destroyed the parts. Try it first on a scrap of the same filament.
How do I join nylon parts?
Polymaker advises against adhesives on nylon because they bond poorly, and recommends mechanical joints instead: screws, clips or snap fits. If you're designing the part, plan holes for fasteners.
How long does the glue take to set?
Cyanoacrylate grabs in seconds to under a minute depending on the format. Epoxies are slower: Devcon Plastic Welder, for example, needs about 10 minutes of initial hold and 24 hours for full strength. The safe bet is to keep the parts clamped until the maker says it has cured.

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