Geometric Dimensioning & Tolerancing (GD&T) – Control Summary

 📐 Geometric Dimensioning & Tolerancing (GD&T) – Control Summary 🧭

GD&T provides a precise language to define allowable variation in form, orientation, location, and runout—ensuring functional fit and interchangeability.

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🔹 FORM CONTROLS

(Control the shape of a feature — no datum reference allowed)

🔲 Flatness

Controls the flatness of a surface.

📏 Straightness

Controls straightness of a surface element or an axis.

⭕ Circularity (Roundness)

Controls roundness of a circular feature.

🛢️ Cylindricity

Controls the overall form of a cylindrical surface.

➡️ Combines circularity + straightness.

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🔹 ORIENTATION CONTROLS

(Control the tilt or orientation relative to a datum)

⟂ Perpendicularity

Controls 90° orientation of surfaces, axes, or median planes.

∥ Parallelism

Controls parallel orientation between features.

📐 Angularity

Controls orientation at a specified angle (other than 90°).

📌 Datum reference is required.

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🔹 LOCATION CONTROLS

(Locate features relative to datums)

🎯 Position

Locates center points, axes, or median planes of size features.

➡️ Also controls orientation.

🔵 Concentricity

Locates the derived median points of a feature relative to a datum axis.

⚠️ Rarely recommended—consider Position, Runout, or Profile instead.

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🔹 PROFILE CONTROLS

🌊 Profile of a Surface

Controls the shape and location of a surface.

➡️ Can control form, orientation, location, and size.

〰️ Profile of a Line

Controls the shape of individual cross-sections.

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🔹 RUNOUT CONTROLS

🔄 Circular Runout

Controls circular variation during rotation.

🌀 Total Runout

Controls overall surface variation, including:

✔️ Form

✔️ Coaxiality

✔️ Orientation

🎯 Key Insight

Selecting the right GD&T control simplifies inspection, improves manufacturability, and ensures functional performance—without over-constraining the design.

source : Six Sigma Manufacturing

Slow steps are still steps

Everyone wants overnight success.

No one wants a 10-year plan.

Too often, we compare someone’s Chapter 15 to our Chapter 1.

We see the wins. The success. The followers.

And we forget that what looks like an “overnight success” probably took 10+ years.

If you're just getting started, it’s easy to feel behind.

But slow steps are still steps. And progress doesn’t need to be flashy to be powerful.

Let go of the pressure to “arrive”.

Stop:

1/ Comparing your timeline to others

2/ Measuring yourself by external milestones

3/ Believing speed equals success

4/ Trying to skip foundational work

5/ Doubting your own pace

Instead:

1/ Celebrate small wins

2/ Focus on one step at a time

3/ Keep a progress journal

4/ Prioritise consistency over intensity

5/ Track how far you’ve come - not how far is left

Success isn’t a staircase you leap up.

It’s a ramp you build - one small, solid step at a time.

⤵️ What’s one thing you’re proud you stuck with - no matter how long it took?

♻️ Repost this to remind someone you know not to rush their growth.

source : Jen Blandos

Image credit: Bookthoughs

The environment changes the perceived value

 Your value changes with the environment.

So does your price.

Think about a bottle of water:

Same product.

Same liquid inside.

But the environment changes the perceived value.

That’s because people don’t just pay for what you sell - they pay for where they find you.

If you’re not happy with what you’re making,

stop blaming the market.

Start looking at:

↳ Where you’re playing.

↳ Who you’re selling to.

↳ How you’re positioning yourself.

I learnt this the hard way.

When I launched my communications and PR training company in the UK, I underpriced myself thinking I’d be booked solid.

Instead, I was ignored by the very corporates and government clients I wanted to work with.

When I raised my rates to match the market’s top tier, I was booked months in advance.

Same service.

Same expertise.

Different perceived value.

Here’s the takeaway:

1/ Everyone has an audience.

2/ Make sure you’re in the right environment - and priced for it.

3/ Cheap can cost you far more than you think.

⤵️ Ever left one room and instantly been worth more in another?

♻️ Repost this to challenge the “charge less, win more” myth.

source : Jen Blandos