Remaking Spare Parts With FDM: From Broken Sample to Repeatable Part

Spare parts are the clearest case for printing. Quantities are tiny, tooling never existed or is long gone, and the cost of waiting is much higher than the cost of the part. A bracket worth 40 euros can hold up a machine that bills several thousand euros a day.

You do not need CAD data to start

Most spare part enquiries arrive as photos of something broken. That is usually enough. What we need are the functional dimensions: hole diameters, hole spacing, installed width, the depth of any recess and the fits at shafts or bearings. Cosmetic contours can be approximated, functional dimensions cannot. A caliper, a sheet of paper with numbers on it and photos from every side with a ruler in frame get most parts reconstructed.

Copy the function, not the original material

An injection moulded ABS cover does not have to be remade in ABS. What matters is the environment the part lives in. Under sunlight ASA outlasts ABS by a wide margin. Next to a heat source PC keeps its shape where PETG creeps. In a dry running gear PA12 or PA12-CF beats almost anything the original supplier used. Tell us the temperature, the load and what the part touches, and the material follows from that.

Fix the reason it broke

A part that failed once will fail again if it is copied exactly. Look at the fracture surface before reproducing anything. A clean break at a sharp internal corner means missing radius. A break at a screw boss means a missing insert or overtightening. A part that has gone brittle and yellow has taken UV. Each of these has an obvious fix that costs nothing in a printed part: add a radius, plan an insert, change the material.

• Add generous radii at internal corners, the single most common failure point on moulded originals
• Orient the part so the main load does not act across layer lines
• Replace printed threads with brass inserts at any point that gets serviced
• Increase wall thickness locally around the failure zone instead of everywhere
• Where a metal original failed by fatigue, check whether plastic is appropriate at all before quoting

A digital inventory beats a shelf

Once a part has been approved, the valuable output is not the part but the file plus the locked parameter set. We keep both on record, so the next order is a one line email instead of a new project. For maintenance teams this replaces shelf stock of slow moving parts with a two day lead time and no capital tied up.

Send photos of the broken part with a ruler in frame and the dimensions you can measure. We will tell you within a day whether it is reproducible and which material fits the application.