A trial print is a decision point. Before testing, connect each critical dimension, fit, movement and visible face to a method and acceptance limit. Then choose acceptance, a targeted revision or another trial from the observations.
A measurement is an observation; approval needs an agreed limit and intended function. The tolerance guide explains why the mating part matters too. Once a trial passes, preserve its model revision and execution before requesting a small batch.
Download the English project worksheet. Open it as UTF-8 CSV, replace the guide context with your project inputs and record observations separately from acceptance decisions. Blank cells do not indicate a passed check.
Identify exactly what you are testing
Record file revision, print ID, date, supplied material and purpose. Do not mix findings from two versions. Define what the trial cannot prove, such as lifetime, production consistency or safety suitability.
Use an orientation sketch when build direction is a test variable. Flexible parts also need a defined movement and recovery requirement; outside dimensions alone cannot assess it.
Set criteria before observing results
For each feature, record desired result, limit, instrument or action, and consequence of rejection. Define visual inspection distance, lighting and reference image. A functional test needs a starting state, action and expected end state. Stop if it could cause damage or needs expertise that is not available.
Read a completed acceptance example
The fictional knob enclosure below demonstrates a decision record. No physical part was tested.
| ID | Feature | Expected | Synthetic observation | Decision |
|---|---|---|---|---|
| M1 | Outside diameter | 30.0 ± 0.2 mm | 30.3 mm | Reject |
| F1 | Snap action | Closes once, stays closed, opens by hand | Stays closed but cannot open by hand | Reject |
| V1 | Front face | No visible damage at 400 mm | Small burr on rear face | Accept within this criterion |
The diameter range is 29.8–30.2 mm, so 30.3 mm is 0.1 mm above the upper limit. These numbers teach the method; they are not measurements of a delivered product.
Link the deviation to its consequence
M1 could obstruct fit; F1 prevents disassembly. Record these observations without presenting a guessed cause or design fix as fact. Request assessment of diameter and release function. A cosmetic deviation is minor only if it lies outside the designated visible area and meets the previously chosen criterion.
Choose revision and retest when a criterion fails
All blocking criteria must pass. In the example, two of three fail, so the decision is revision and another trial, not partial approval. Keep passed observations as context, but retest changed and dependent functions. Changes to geometry, material or orientation can invalidate earlier findings.
Keep a reproducible handover
Record version, function, critical dimension, fit action, visual criterion, deviation-photo ID, consequence and final decision. Retain raw measurements; mark pass only after comparison. Include the decision-maker and date. Without the instrument, action or photo reference, the result remains incomplete.
Let the trial result determine the next order
If criteria are not yet defined, request a prototype around one clear question. If a first version fails, send the recorded revision, measurements and photographs and ask for cause assessment and the next change, rather than another identical copy.
If every agreed check passes, take the approved revision, material execution and variants to small-batch 3D printing. Agree what stays fixed and what is checked per item. One accepted prototype is the reference for that agreement, not proof that every future print is already approved.