Architectural Flashing Supply
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Dimensional inspection and tolerances · Lesson 1 of 4

Dimensional inspection and tolerances: principles and terminology

What a formed piece is checked against, the words inspection uses, the tool for each check, and why zero, calibration and traceability are different things.

You will be able to: Define nominal, tolerance, mold line and Blank Width, name the tool for each check and what zeroing and calibration mean, and state the safety boundaries of measuring at the folder.

11 min · 11 slides · 10 questions

All lessons in this module
Slide 1 of 11

What inspection checks

Dimensional inspection compares a formed piece with its order before it leaves the shop: material, thickness, finish and painted side, each leg, each bend angle and its direction, the hems, Blank Width, length, piece count and flatness.

Inspection checks the piece against its order, never against memory.

Sources

Videos for this lesson

What this video shows: Mitutoyo's product demonstration of dial caliper use: the instrument maker's own guidance, for reference.

Video: How to Read a Caliper (Dial Caliper Use - Mitutoyo) by Mitutoyo America Corporation, on YouTube. Chosen from the video's published description.

Glossary

Nominal
The named size of a dimension or thickness, such as 24 ga galvanized at 0.0276 in.
Tolerance
The permitted band around a nominal value, set by the order, the project specification or the product standard.
Mold line
The theoretical sharp corner where two flat faces of a bend would meet; AFS dimensions every leg to it, on the face outside the first bend, never to the centre of the sheet.
Blank Width
FlashDraft's sum of the mold-line legs plus hem allowances: a quoting figure, not a developed blank.
Zero check
Confirming a tool reads zero with nothing between its faces before measuring.
Calibration
Comparing a tool's readings with a known traceable standard. Not the same as adjustment (re-zeroing). In the bend allowance module, 'calibrating K' means working K out from test pieces, a different use of the word.
Metrological traceability
A result related to a reference through a documented unbroken chain of calibrations.