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Custom transformer and solenoid coil bobbins (resin, mm-accurate)

A precision micro-component project: coil bobbins with core openings and wire-guide features, designed in CAD and produced in resin for consistent detail.

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A set of small resin-printed coil bobbins with core openings.

Project snapshot

Item Details
Process Resin (MSLA) after FDM prototyping trials
Material Photopolymer resin (white / grey / clear, per request)
Size Typically ~15–25 mm
Quantity ~40–50 parts total
Turnaround ~1–2 days (design + print, depending on complexity)
Pricing Typically £5–£8 per part (depends on design + batch size)

The brief

Produce small coil bobbins (transformer/solenoid-style winding formers) with a central opening for a core and features that make winding easier: channels, slots, and clean edges.

The client sometimes provided rough sketches (including hand-drawn 2D drawings) and sometimes requirements were clarified in conversation. Dimensions were provided in millimetres.

Why resin (after FDM tests)

We initially tested FDM — even with a 0.2 mm nozzle — but the combination of detail, surface quality and strength wasn’t good enough for this part size and geometry.

A small FDM-printed coil bobbin prototype showing why the FDM approach was not suitable for the required detail.
Early FDM trials helped confirm the limits at this scale — resin was the better tool for the job.

Switching to photopolymer resin provided crisp small features and more consistent results across a batch.

CAD design (built from scratch)

Each bobbin was modelled from scratch in CAD based on the client’s dimensions.

Common design features included:

  • Core openings (square/rectangular/round)
  • Wire channels and guide slots
  • Small reliefs to prevent snagging during winding
  • Variants in round and rectangular formats
Rectangular resin-printed coil bobbins shown in hand for scale.
These are genuinely small parts — resin printing keeps edges and openings clean at mm-scale.

Production and variants

Over roughly ten orders, multiple variants were produced and refined. Resin colour was chosen per request (white, grey, clear).

Round resin bobbins printed on supports before cleaning.
Supports are removed during post-processing; resin enables consistent small features across the run.
A coil bobbin printed in clear photopolymer resin.
Clear resin is useful when visual inspection matters or when a client prefers that look.

Result

A set of mm-accurate coil bobbins produced in resin with clean detail and predictable fit — a good example of choosing the right manufacturing method for precision micro-components.

Related: Resin 3D Printing, Resin, 3D Design & File Support, Get a Quote.

Related

Resin 3D Printing

See resin capabilities, typical layer heights and turnaround.

Resin (MSLA)

Material notes, finish expectations and practical trade-offs.

Projects & examples

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