Hear us out: PPS-CF holds its shape past 486.5 °F (252.5 °C HDT), doesn’t sustain a flame (UL94 V-0), and won’t scratch the polished stainless you just spent an hour on. We design the fixture so polymer never sits in the direct joint — it locates, cradles, and stops; your steel and your hands do the welding.
Every fabricator says the same thing, and it’s the right instinct — most plastic has no business near an arc. PPS-CF isn’t most plastic. It’s the polymer that lives in engine bays and chemical plants, carbon-fiber reinforced, printed on machines that run a 350 °C nozzle. The discipline isn’t pretending plastic is steel — it’s designing the tool so each material does what it’s actually good at.
PPS-CF holds rigidity at temperatures that destroy nylon tooling. Spatter proximity and near-weld heat are design inputs, not disqualifiers.
Flame-rated V-0 — it doesn’t sustain a flame. A stray arc strike chars a corner; it doesn’t start a fire on your table.
The fixture cradles, aligns, and stops the work — and keeps polymer out of the direct weld path by design. Where the torch goes is between your steel and you.
These are published cases from the industrial FDM literature — their numbers, not ours. We cite them because the application is proven; we build the same classes of tooling in the same classes of material, locally.
Custom welding fixture, published Markforged case study. Fixture build time 156 hours → 12. Roughly $800 in steel and labor → about $10 in printed material.
Siegmund — the German welding-table company fabricators actually buy — catalogs polyamide prisms and stops for exactly this use. The category isn't an experiment. What the catalog can't do is cut a V-block for your diameter, this week, that's never been stocked anywhere.
Part-specific locating and clamping geometry for repeat weldments. The setup that took your best fitter an afternoon, repeatable by anyone on the floor.
Round-stock cradles cut to your exact diameter, not the three sizes the catalog stocks. Non-marring on finished, polished, and stainless work.
Locating stops and fences for your table's grid, printed in batches for pocket change.
Hold the assembly at the right height and angle while you tack — without a second pair of hands.
Hole patterns and scribe templates to your spec, with press-fit steel bushings where the operation demands them.
Clamp faces and vise jaws that hold finished work without leaving a mark on it.
Near-arc work runs PPS-CF; PA12-CF and PA6-CF carry the general-fixturing load away from the heat; polycarbonate where impact and clarity matter. Anything bolted or clamped gets metal in the bolt path — heat-set inserts and compression limiters — so preload runs through steel, not creeping polymer.
And we’ll tell you no when polymer is the wrong answer: clamping squares that hold a reference under weld-shrinkage load, long cantilevers under sustained load, anything precision-ground where steel’s stiffness is the actual product. A fixture that fails on your table costs us more than the order.
Send a STEP file, a drawing, or a photo of the weldment and how you’re fixturing it today. We’ll come back with price and lead time — typically same day.