1/8" NPT Heat Set Insert for 3D Printing – Brass NPTF Pipe Thread Insert

Real pipe threads for your 3D prints.

Tapping NPT threads straight into plastic gives you weak, leak-prone threads that strip the second time you tighten a fitting. This brass heat set insert melts into your print and gives you a 1/8-27 NPTF thread that holds up to wrenching, reassembly, and real-world use.

Built for boost and vacuum ports, temperature and pressure sensor bungs, gauge lines, and air or fluid fittings in printed intakes, manifolds, enclosures, and fixtures.

Why this insert?

Anti-rotation double-D flange: flats on the flange resist spinning when you tighten a fitting into the insert.
Two helical knurl bands: resist both pull-out and torque-out.
Solid brass: won’t corrode or gall like steel threads in plastic.

Specifications

Thread 1/8-27 NPTF
Recommended hole 0.475" (12.07 mm) diameter, 0.55" minimum depth
Overall length 0.57"
Body length (below flange) 0.50"
Knurl OD 0.51"
Pilot OD 0.47"
Flange 0.55" diameter, 0.50" across flats, 0.07" thick
Material [Brass alloy]

Designing the hole

Model a straight 0.475" (12.07 mm) hole, at least 0.55" deep, so displaced plastic has room below the insert.
Keep at least [0.125"] of wall around the hole.
For a flush finish, add a 0.07"-deep counterbore matching the flange.

Installing

Heat the insert to roughly your filament’s printing temperature using a large flat soldering tip or a heat-set press.
Push it in straight until the flange is flush. Don’t twist.
Let it cool completely before threading in a fitting.

Sealing

Most fittings are standard NPT, not NPTF, so use PTFE tape or thread sealant on the fitting.

Tested in: [PETG, ABS, ASA, PA-CF]

FAQ

Q: Will a regular soldering iron tip work?
A: Not well. Standard tips are sized for M3 and M4 inserts. Use a large flat tip or a heat-set press

Q: Can I use it in PLA?
A: Yes, with care. PLA softens at relatively low temperatures, so avoid hot under-hood locations.

Q: Is the bore a through hole?
Yes. Your printed passage should line up with the insert’s bore.

Q: Does it work with BSPT fittings?
No. 1/8" BSPT has a different thread pitch (28 TPI) and angle. Use NPT fittings only.