A row of holes can have the expected overall span while one hole sits in the wrong place. If our report reduces the row to an average pitch, that local error may disappear from the summary. With an automatic video measuring machine, we can build a more useful record by keeping each hole identity and each required interval visible. The report should answer the drawing requirement before it compresses the measurements into a convenient headline.

Equipment demonstration: the video shows our vertical and horizontal integrated measurement system. It illustrates a dimensional inspection workflow, rather than a controlled experiment on the numerical hole pattern described below.

A simple example shows the cancellation

Consider four ideal hole centres on a straight X-directed row at 0, 10, 20 and 30 mm. There are three adjacent intervals. Now imagine that only the second centre moves to 10.2 mm, with the other centres unchanged. The signed X intervals become 10.2, 9.8 and 10.0 mm. Their average remains 10.0 mm, and the first-to-last X separation remains 30.0 mm. These are illustrative coordinates, not measured product data or an acceptance specification.

The average has not failed arithmetically. It has answered a different question. Positive and negative interval deviations cancel. The local displacement is visible when we retain the intervals, but it is hidden when we inspect only their mean. Whether that displaced hole is acceptable depends on the actual drawing and tolerance; an attractive average cannot supply a missing acceptance rule.

State which distance the programme calculates

On a vision measuring machine, a centre-to-centre distance can mean a signed X component, a Y component or a two-dimensional straight-line distance. Our cancellation example uses X components on a straight row. We should not transfer its algebra without qualification to a curved pattern or to the sum of arbitrary Euclidean distances. The selected coordinate system, direction and distance construction belong in the programme review.

Cumulative distance from a named starting hole is another useful output, but it is not identical to adjacent pitch. It can reveal accumulated displacement along a row, while a single end-to-end measurement can still overlook an intermediate error. We select the needed outputs from the dimension scheme: chained spacing, baseline dimensions and geometrical location requirements are not interchangeable just because they involve the same centres.

Give every hole a stable identity

Batch inspection with a desktop instant vision measuring machine can produce many results quickly. Before summarising them, we assign a repeatable order such as H1 through H4 and record the orientation that determines it. We check that the programme has not skipped a hole, counted one twice or restarted the numbering from the opposite end. A complete table with unstable identities is difficult to compare across parts.

For parts inspected using a Vertical and Horizontal Integrated Instant Vision Measuring Machine, we also state which view supplies each feature. A side opening and a top-view hole may belong to different constructions. We do not let a convenient view silently change the feature being measured. Where the required centre cannot be established reliably from the available image, we review the measurement approach before accepting the derived pitch.

Preserve the individual values before adding a summary

Our report starts with the drawing characteristic identifier and the measured value needed to judge it. Where adjacent spacing is specified, each required pair gets its own row. Where location relative to a datum system is specified, we retain the necessary location results. The mean, range or overall span can be additional process information. These summaries should remain recognisable as summaries, with their own labels and units.

A useful review asks whether the summary can stay unchanged when a relevant individual feature moves. If the answer is yes, we know that the summary alone is insufficient for that decision. We can demonstrate this using a deliberately altered set of coordinates during report design, without claiming that a real production part has been tested. The purpose is to test the logic of the output, rather than to invent evidence of machine performance.

Check the measurement and the decision together

An Optical Measuring System still needs an appropriate edge strategy, a justified centre construction and a suitable setup for the part. If repeated measurements fluctuate, we investigate those conditions before interpreting small interval differences as process changes. Conversely, a stable result does not make the wrong report characteristic suitable. Repeatability and relevance both matter, and neither is established by the average pitch alone.

At HANDING OPTICS, we can review the proposed inspection table alongside the drawing when discussing a Vision Measuring System. Send the hole pattern, required dimensions and a representative sample description to handing3d@163.com. We will help define a workflow that retains the individual information needed for the decision, while using summaries to support process understanding.