Choose a material for jigs and fixtures

Printed jigs, fixtures, gauges and end-of-arm tools are one of the best returns on a 3D printer. They are made in small numbers, change often and save hours on the line. But they have to stay accurate under clamping, repeated use and the occasional knock.

What fails

• Flex. A fixture that bends under clamping holds the part in the wrong place. This is the most common failure, and it is about stiffness, not strength.
• Creep. Locating features slowly move under constant load, especially in warm workshops.
• Wear. Locating pins, slots and contact faces wear down with every cycle.
• Chemical attack. Cutting fluids, solvents and cleaners can swell or crack some plastics.
• Warping. Large flat bases that warp during printing are never accurate.

Which properties matter

Stiffness comes first. Look at flexural modulus and Young’s modulus. A higher value means less bending under the same load.

Next, check heat deflection temperature if the fixture sits near welding, curing ovens or hot parts. Impact strength matters if fixtures get dropped. For gauges, low warping and good dimensional stability matter more than any single datasheet value.

Our engineering filaments show a flexural modulus of 856–51,000 MPa (median 2,550 MPa, 99 materials).

1. ABS 17856–5,260
2. PETG 141,068–5,740
3. PC 122,050–6,540
4. PA6 92,050–7,038
5. PA12 61,260–11,100
6. PEEK 102,400–11,200

Bar = lowest to highest, dot = median. 68 materials, live from our database.

Material families that usually work

• Carbon-fibre nylon and PETG are the go-to choices. Chopped fibre adds stiffness and reduces warping.
• Continuous fibre reinforcement, available on some systems, gives metal-like stiffness along chosen paths.
• PETG and ABS are fine for light-duty fixtures and quick iterations.
• PC and glass-filled grades suit fixtures that see heat or impact.
• Rigid and tough resins give the precision needed for small gauges and assembly nests.
• PA12 powder gives tough, isotropic fixtures with good chemical resistance.

Process considerations

FFF is the most common choice: cheap, fast and able to print large fixtures. Fibre-filled filaments are abrasive, so use a hardened nozzle. Resin gives fine detail and tight tolerances for small parts, but brittle grades can chip. Powder parts are strong in every direction and need no supports, which suits complex nests.

Design and post-processing tips

• Design for stiffness. Ribs, deeper sections and closed box shapes add far more stiffness than a stronger material.
• Use more walls, not just more infill. Stiffness lives in the outer skin.
• Keep bases flat and stable. Use a brim or enclosure for large footprints, and split very long fixtures into bolted sections so warping cannot spoil the whole part.
• Check chemical compatibility with your cutting fluids and cleaners. Nylon and PP generally cope well; ABS and many resins can be attacked by solvents.
• Add metal where it wears. Press in dowel pins, bushings and threaded inserts for locating and clamping points.
• Orient for load. Keep clamping loads along the layers, not across them. See print orientation.
• Anneal carefully if you need more heat resistance, and check dimensions afterwards.
• Label the fixture with part number and revision. You will print more versions than you expect.

A shortlist from our data

The stiffest carbon-fibre filaments in our catalog by flexural modulus:

Common mistakes

• Choosing by tensile strength when the fixture fails by bending.
• Using a brass nozzle with carbon-filled filament.
• Relying on printed plastic for high-wear locating features.
• Forgetting that fixtures warm up in hot workshops and drift.

Find stiff carbon-fibre materials