A production fixture for medals, coins and buttons must control position, rotation, height and seating while protecting the finished surface and keeping the print path clear. The design is successful when different operators can repeatedly load approved parts, print within the agreed positional tolerance and trace a defect to a specific pocket or setup condition.

A round pocket is not automatically a complete solution. It may locate the center of a coin but cannot control orientation unless the artwork is rotationally symmetric. The fixture needs a repeatable rotational datum whenever text, a portrait, a loop, a pin or another feature defines “up.”

Measure the real part family before designing pockets

Collect representative parts from the intended production lot and measure the features that determine seating: outside diameter, thickness, rim, recess, dome, loop, clasp, pin and any coating buildup. Record the observed range rather than designing from one ideal drawing. Separate visibly similar parts when their back features make them sit differently.

Define the printable face and areas that must remain untouched. A decorative plated surface can be damaged by a tight pocket or abrasive loading edge. A button pin may prevent the face from sitting level. A medal loop can help control rotation, but only if its variation and strength make it a reliable datum.

Choose datums that make incorrect loading obvious

Use a stable primary datum to establish X–Y location, then add a secondary feature to control rotation. The outer circular edge can locate center; a flat, notch, loop, seam or keyed insert can establish orientation. The operator should not need to judge a small angle by eye.

Connect the physical datum to the artwork template. Give the fixture a defined origin, and keep pocket numbering identical in the fixture, print file and job traveler. If pocket 12 repeatedly shifts, that identity lets the team inspect its seating or geometry instead of changing a global artwork offset.

Control height, restraint and printhead clearance

Design for the tallest approved combination of part and fixture, including measured variation, debris risk and the safety margin required by the printer instructions. Every part should present a stable printable face without rocking. Do not use the printhead as a height probe, and do not assume vacuum alone will restrain small, uneven or perforated pieces.

Restraint must resist movement caused by carriage motion and loading without bending pins, marking plating or covering the print zone. Add lead-ins or finger access so operators can load and remove parts without scraping them. Keep open gaps and unnecessary head height under control; excessive distance can contribute to misting or overspray. Roland’s jig guidance likewise emphasizes holding objects flat and close to the print path while managing gaps and height.

Balance pocket count with repeatability and inspection

More pockets do not guarantee more accepted output. A densely packed fixture may become slow to load, hard to inspect or too flexible to hold its shape. Compare the value of extra positions with loading access, fixture stiffness, artwork complexity and the ability to isolate a failed pocket.

For mixed parts, do not place different thicknesses into one fixture unless the approved setup can maintain clearance and focus across the entire load. If the workflow requires frequent product changes, modular inserts may be easier to revise and store than a new full-bed plate for every variation. Each insert still needs an identity and approved part range.

Run a fixture acceptance test before batch release

1. Measure representative part variation and identify surface-protection risks.
2. Define the primary position datum and the rotational datum.
3. Build a labeled prototype with a controlled origin and numbered pockets.
4. Load every pocket repeatedly, preferably with more than one trained operator.
5. Print a registration target or alignment-sensitive artwork using the approved setup.
6. Measure or inspect placement against written tolerance; record results by pocket.
7. Check removal, surface marking, part stability and cleaning.
8. Repeat after changeover, then approve, revise or reject the fixture.

Diagnose the pattern before changing artwork

If every position shifts in the same direction, check fixture origin, bed position and file origin. If one pocket repeatedly fails, inspect that pocket’s datum, debris and wear. Random rotation suggests that the fixture locates center but does not control orientation. Focus or misting that changes with the part often points to height, seating or clearance rather than a universal file error.

Preserve the last accepted sample and map defects by pocket. Change one variable at a time. Compensating for a mechanical problem with individual artwork offsets may hide the immediate symptom while making the fixture harder to maintain and reproduce.

Release and maintain the fixture as production tooling

Assign a fixture ID and revision. Record the approved part numbers and dimensional range, datum logic, origin, artwork template, maximum wear or damage, cleaning method, storage location and revalidation triggers. Revalidate after repair, origin changes, new part lots, visible wear or repeated position-specific defects.

The best fixture is not the tightest one or the one with the most pockets. It is the tooling that lets the production team load safely, verify setup, identify failures and reproduce an approved result.

Frequently asked questions about UV printer jigs and fixtures

Can one UV printing jig handle different coin sizes?

It can use controlled interchangeable inserts, but each insert needs an approved part range, datum, height, origin and revision. Uncontrolled mixed heights can create clearance and quality risks.

Why can a round part rotate in a round pocket?

A circular edge locates the center but provides no unique angular reference. Directional artwork needs a second feature, such as a loop, flat, notch or keyed insert, to define orientation.

How many pockets should a fixture have?

There is no universal number. Balance capacity against stiffness, loading access, inspection, artwork control and accepted output rather than maximizing density alone.

When should a fixture be revalidated?

Revalidate after repair, origin changes, a new part lot, visible wear, repeated position-specific defects or any change to the approved part range or setup.

References

1. Roland DG, How to Make Jigs for UV Printing Direct to Objects — holding, flatness, gap and height considerations (accessed September 9, 2026).
2. artisJet, UV Printing Jigs — examples of object-specific jig applications (accessed September 9, 2026).