If you’ve worked in manufacturing for any length of time, you’ve probably had the experience of staring at a Feature Control Frame and wondering what, exactly, it’s trying to tell you.
You’re not alone. GD&T has a reputation for being cryptic. The symbols look like something between Egyptian hieroglyphics and a circuit diagram. And the ASME Y14.5 standard itself is about as readable as a legal document—which, in a way, it is.
But here’s the thing: GD&T exists for a reason. It’s the language that connects design intent to manufacturing reality. When a designer puts ⌖ ⌀0.25 Ⓜ | A | B | C Ⓜ on a drawing, they’re communicating something specific about how that feature needs to function in the real world. The alternative—plus/minus tolerancing—just doesn’t cut it for anything remotely complex.
So we’re stuck with GD&T. And if we’re stuck with it, we might as well make it easier to work with.
The problem isn’t the standard
We’ve trained a lot of engineers on GD&T over the years. The pattern is almost always the same: people understand the concepts, but they struggle with the application.
They can tell you what position tolerance means. They understand MMC and bonus tolerance in principle. But when they sit down to write an FCF for an actual part, doubt creeps in. Did I get the datum order right? Is this modifier allowed here? Should I be using profile instead of position?
The standard has answers to all these questions. But the standard is 450 pages long, and nobody has time to cross-reference it for every callout.
What people need isn’t more GD&T training. They need a tool that tells them when they’re about to make a mistake.
What we built
DatumPilot started as an internal tool at Ingenivue Engineering Services Inc. We were doing a lot of design work for clients in automotive and aerospace, and we kept running into the same problem: validating our own GD&T.
We’d build an FCF, think it looked right, then second-guess ourselves. Is this actually ASME-compliant, or does it just look like it is? We’d pull out the standard, flip to the relevant sections, and spend twenty minutes confirming what we already suspected.
So we built a thing. A web app where you construct an FCF visually, and it tells you—in real time—whether it’s valid. Not “probably valid.” Not “this looks about right.” The app checks against 30+ rules derived from Y14.5-2018 and tells you exactly what’s wrong and where.
Then we added tolerance calculators. Position at MMC, bonus tolerance, virtual condition—all the math that used to live in spreadsheets. Input your numbers, get your answer, move on.
Then we added AI explanations. Not AI that makes up GD&T rules (that would be a disaster), but AI that takes a valid FCF and translates it into plain English. So when your purchasing team asks what a callout means, you can send them a paragraph instead of making them decode symbols.
Why “accessible” matters
Here’s the part that might sound like marketing, but bear with us: we think making GD&T more accessible is genuinely useful for manufacturing.
Not because GD&T is too hard. It’s not. It’s a logical system, and anyone can learn it. But the barriers to entry are higher than they need to be. The tools are clunky. The feedback loop is slow. The cost of getting it wrong—scrapped parts, failed inspections, supplier disputes—is real.
When GD&T is easier to work with, more people use it correctly. Drawings are cleaner. Inspectors spend less time interpreting ambiguous callouts. Suppliers don’t have to call and ask what you meant.
We’re not claiming DatumPilot will solve all your manufacturing problems. But if it means one fewer rejected part, one fewer back-and-forth email with a supplier, one fewer hour spent hunting through the ASME standard—that’s a win.
Try it yourself
DatumPilot has a free tier. Not a trial, an actual free version with limits. You can build FCFs, run validations, see how the explanations work.
If it’s useful, great. If you outgrow the free tier, there’s a paid version with more headroom. If it’s not for you, no hard feelings.
We built this because we needed it. Turns out other people need it too.