FittingsFab — 3D printable NPT pipe coupling designer
Coupling Designer · fittingsfab.com
FittingsFab
Can't find the fitting you need? Pick the thread size for each end — any NPT from 1/8" to 2" — and the drawing and dimensions update as you go. Download a print-ready STL with real tapered threads and a full water passage: test-fit it in PLA, then make the final part in nylon, bronze or stainless steel.
Design the coupling.
Every coupling is three sections: the left end, a hex body, and the right end. Water flows straight through. Pick a thread spec and length for each. The drawing updates live.
recessed socket — accepts a stud
US pipe thread · tapered, seals on the threads
barrel between the two ends
Max ⌀22.4 mm keeps safe wall thickness.
recessed socket — accepts a stud
US pipe thread · tapered, seals on the threads
Inspect the 3D model.
Real helical thread geometry, not a decorative texture. Drag to orbit, scroll to zoom.
Download 3D model and print.
Order the final version.
A burst fitting does far more damage than the part costs. Even a garden hose that bursts can mean hundreds of dollars in repairs and a big water bill; indoors, a leak while you're away can cost hundreds of thousands to repair. Unless the fitting is outdoors, low pressure, and a leak wouldn't cost you anything, order the final part from a professional print service instead of printing it at home.
- Print at 0.12–0.16 mm layers on your own printer.
- Screw it onto the real pipe by hand — no tape.
- Check it seats without wobble and the hole lines up.
Tip: test fit a PLA copy first — it costs cents, a metal part does not.
A burst fitting can do far more damage than the part costs: outdoors, a burst hose can flood a yard and run up a large water bill, and indoors a leak while you're away can cost hundreds of thousands to repair. Order the final part from a professional print service — nylon for outdoor cold water, stainless 316L or bronze for anything indoors, hot, or hidden in a wall.
Material: Nylon PA12 (SLS / MJF), finish: vapor smoothing, qty 1. Threaded part: 3/4" FNPT x 1" FNPT. Do not reduce wall thickness or modify threads.