Metrology & Inspection

"In spec" is a measurement, not an opinion. CAD Custom verifies critical dimensions on-site with calibrated metrology tooling — Sylvac and Fowler digital height validation on the granite plate, and Starrett HE350 optical profile comparison for the features a contact instrument cannot see.

Because the inspection bench sits steps from the machine, parts are checked as they come off — not shipped across town to a third party while your schedule waits. Problems surface while there is still time and material to fix them, which is precisely when finding them is cheap.

What leaves the shop is a part and its numbers: dimensions you can hand to your own customer, not just a promise. For assemblies and repeat work, that record becomes the baseline every later batch is measured against.

Why 'in spec' has to be a measurement

Every shop will tell you their parts are in spec. The useful question is: according to what? An eyeball and a calibrated instrument produce the same sentence — "looks good" — with wildly different meanings. Machined parts fail quietly: a bore half a thousandth small still accepts the shaft, but presses instead of slides; a mounting face out of flat still bolts down, but preloads the assembly with stress that shows up later as the mystery failure nobody can reproduce.

Metrology exists to replace those quiet failures with loud, early, cheap ones. At CAD Custom, inspection is not a claim; it is an activity performed on calibrated instruments with results written down. Critical dimensions are verified — not sampled by vibe — against the print's callouts before parts ship. When a number is out, it is out in Banks, Oregon, where the machine, the program and the material are all within reach, instead of out on your assembly floor where it costs ten times as much to matter.

This page describes the bench where that happens, what the instruments actually do, and what the discipline is worth to you as a buyer of parts that must fit things.

The bench: granite, height gauges and optical comparison

Good measurement starts with a reference you can trust. The heart of the inspection area is a black granite surface plate — granite because it is dimensionally stable, wear-resistant and machined flat to a degree no steel table maintains. Every height measurement in the shop ultimately stands on that flatness.

On the plate, Sylvac and Fowler digital height gauges do the linear work: heights, depths, steps and locations, read out electronically to eliminate the interpretation errors of vernier scales. Digital instruments also make repeatability visible — measure the same feature five times and the spread tells you the truth about both part and process. Alongside them, dial indicators sweep surfaces for flatness and runout, and micrometers and calipers handle the everyday dimensions.

The instruments are calibrated and maintained on-site, which matters more than the badge on any single tool: an uncalibrated micrometer is a random-number generator with a comforting feel. And the bench sits inside a working machine shop's quality loop — the American and Swiss tooling on it was chosen for accuracy and honesty, not for the brochure. When a customer's print calls a dimension critical, this is where that dimension stops being a drawing note and becomes a verified number.

What optical profile comparison catches

Some geometry defeats contact measurement. A thread's flank angle, a small radius blending two surfaces, the profile of a narrow groove, a delicate feature a probe tip would deflect or simply cannot enter — pressing an instrument against these either fails to reach them or changes what it touches. This is optical territory.

The Starrett HE350 optical comparator works by silhouette: the part is placed in a light path and its magnified shadow is projected onto a screen, where the actual profile can be compared directly against the intended geometry. Nothing touches the feature, so nothing deflects it — the part testifies in its own shape. Radii, angles, thread forms and fine contours that would be arguments with a caliper become plainly visible facts at magnification.

For customers, the comparator closes the honesty gap on exactly the features most shops quietly skip. Small, precise geometry is often the functional heart of a part — the seal groove, the thread that must not gall, the radius that kills a stress concentration — and 'we couldn't really measure that' is not an acceptable note to find attached to it. At CAD Custom the optical check is part of the standard repertoire: if the print draws it, the bench can see it, and what the bench sees gets recorded with the rest of the part's numbers.

Inspection where it belongs: next to the machine

Where inspection happens shapes what inspection can do. Send parts across town to a lab and measurement becomes a verdict — delivered after the run is finished, when every part in the batch already carries whatever error the first one had, and your schedule waits on the courier both directions.

Keep the bench a few steps from the spindle and measurement becomes a control. First articles are verified before a batch commits; in-process checks catch tool wear and drift mid-run, while the fix is an offset instead of a scrap bin; a suspicious feature can go straight from vise to granite plate and back inside ten minutes. The machinist and the measurement talk to each other all day, and the parts get better because of the conversation.

There is a schedule benefit hiding in this too. Because verification is internal and immediate, finished parts do not idle in an inspection queue — the last part off the machine can be measured, documented and boxed the same day. And because problems are caught at correction size rather than catastrophe size, the dates quoted stay the dates delivered. Quality systems are often described as bureaucracy; arranged this way, quality is simply how the shop steers.

The paper trail your parts deserve

A part without its numbers is a rumor. A part with its numbers is a component you can build on — literally and organizationally. Every job at CAD Custom ships with its measurements: the critical dimensions from the print, as-measured values from the calibrated bench, recorded against the first article and the checks made across the run.

That record works for you in several directions at once. Downstream, it is evidence you can hand your own customer or quality system without re-inspecting what you bought. Upstream, it is the baseline for every repeat order — 'match the last batch' becomes a measurable requirement, because the last batch is documented. Sideways, it is diagnosis: when an assembly misbehaves, documented parts can be ruled in or out as the cause in minutes, which is precisely when you least want to be guessing.

For work in demanding industries — aerospace hardware, marine and clean-energy components, fixtures for tech and AI production lines — this paper trail is not a nicety; it is the difference between a vendor and a liability. It costs discipline to produce, which is exactly why it is rare, and exactly why it is standard here. If your current parts arrive as rumors, the form below is where that changes.

What buyers ask about inspection

Is every part measured, or just samples? First articles are measured completely against the print's critical callouts, and runs carry in-process checks at intervals sized to the job's risk — tight-tolerance features get watched closely, forgiving ones sensibly. The plan is stated up front, so 'inspected' is never a vague word on your quote.

Can you report in the format my quality system needs? Measurement results are recorded against your drawing's callouts, and reporting is arranged to fit the customer — from a simple as-measured sheet beside each dimension to structured first-article-style documentation for regulated industries. Tell the shop what your QA process consumes and the paperwork is shaped to feed it.

My print has GD&T on it — is that a problem? No; geometric callouts are read as intended, and each is verified with the appropriate method on the bench — height gauge and indicator work from datum surfaces on the granite plate, optical comparison for profiles and form. Where a callout is ambiguous or seems to fight the part's function, you get a question before machining, which is when questions are cheap.

Do you inspect parts you didn't machine? The bench exists first for the shop's own work, but measurement conversations — a reverse-engineering project, a dispute about a vendor's part, a worn component that needs its true dimensions recovered — are welcome. Describe the need in the form below and the shop will tell you honestly whether it is the right tool for the job.