The short answer
On turned-shaft RFQs, **concentricity** and **runout** are not interchangeable GD&T notes. Concentricity controls median-point alignment of features to a datum axis and is expensive to inspect. Runout (circular or total) controls surface variation relative to a datum axis in a single setup and maps more directly to lathe process capability. Silence on **which control** and **which datum** is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate bands—not the blank diameter alone.
This guide is for buyers packaging steel shaft RFQs where drawings mix “concentric to A” language with journal/runout intent. Illustrations use an **Example part** only—not a customer robot shaft. Related notes live in [keyway callouts on CNC turned shafts](https://3dwk.com/resources/keyway-callouts-on-cnc-turned-shafts), [GD&T callouts that raise CNC quote bands](https://3dwk.com/resources/gdandt-callouts-that-raise-cnc-quote-bands), and [datum schemes for multi-setup CNC parts](https://3dwk.com/resources/datum-schemes-for-multi-setup-cnc-parts); here we focus on **concentricity vs runout labeling** so estimators do not guess.
What each control means for quoting
**Circular runout** limits how much a surface wobbles when the part rotates about a datum axis—typical for bearing journals and seal diameters. **Total runout** extends that along the full length of a cylinder or face. **Concentricity** (ASME) asks for median-point cloud alignment and often forces CMM strategies that do not match a simple dial-indicator shop check. Process pages for robotics steel ([CNC turning Steel 1018 robotics](https://3dwk.com/en/cnc-turning/steel-1018/robotics.html), [CNC 3-axis Steel 1018 robotics](https://3dwk.com/en/cnc-3axis/steel-1018/robotics.html), [CNC turning Steel 1018](https://3dwk.com/en/cnc-turning/steel-1018.html)) assume clear journal/datum notes when lots mix soft-turn and grind stock.
Do not bury “concentric OK” inside a notes cloud. Put **CIRCULAR RUNOUT 0.05 TO DATUM A ON Ø20 JOURNAL** or **TOTAL RUNOUT 0.08 TO A ON Ø28 SEAL LAND** on the PDF and mirror it in RFQ text. Background: [DFM checklist before an online CNC quote](https://3dwk.com/resources/dfm-checklist-before-online-cnc-quote), [what files to send for a CNC quote](https://3dwk.com/resources/what-files-to-send-for-cnc-quote).
Datum axis, setups and stock
Runout only means something when the datum axis is machinable and inspectable in the same family of setups. Soft jaws or collets that redefine “A” between ops widen bands—see [soft jaws vs vise CNC production lots](https://3dwk.com/resources/soft-jaws-vs-vise-cnc-production-lots) and [how workholding changes CNC quote](https://3dwk.com/resources/how-workholding-changes-cnc-quote). Leaving grind stock on journals without naming runout stage (as-turned vs after grind) also forces **needs_manual**.
Bar $/kg planning bands (estimates only): Steel 1018 ~1–2 range under **rates.v1.1** material tables; material cost is rarely the concentricity story—inspection method and datum clarity are.
When concentricity actually belongs
Use concentricity when a standard or customer print family truly requires median-point control and you accept CMM-heavy verification. For most shaft buyers controlling bearing fit and seal wobble, **runout to a named datum** is the clearer RFQ language. If a legacy drawing says concentricity but the acceptance plan is dial-indicator runout, say so explicitly so the quote path matches the shop check.
Tolerance and inspection traps
Calling “concentric within 0.02” without a datum, or mixing concentricity on one diameter with runout on another without a shared A, leaves CMM and shop criteria ambiguous. Default non-critical envelope to ISO 2768-m and put functional runout only on journals and seal lands. Related: [CMM sampling plans for CNC lots](https://3dwk.com/resources/cmm-sampling-plans-for-cnc-lots), [surface roughness Ra callouts that raise quotes](https://3dwk.com/resources/surface-roughness-ra-callouts-that-raise-quotes).
Illustration 1 shows an **Example part** shaft with labeled circular runout on a journal versus a vague concentricity cloud on the same envelope.
Example part walkthrough
**Example part:** Steel 1018 turned shaft ~Ø28×180 mm, Ø20 bearing journal, Ø28 seal land, keyway mid-span, ISO 2768-m general. With STEP + **CIRCULAR RUNOUT 0.05 TO DATUM A (CENTERING DIAMETERS) ON Ø20; SEAL LAND TOTAL RUNOUT 0.08 TO A**, expect a usable automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with silent CAD and “all diameters concentric 0.02” often lands DFM notes or **needs_manual**—without inventing any customer PO.
Illustration 2 contrasts a vague RFQ (“concentric OK / runout as needed”) versus a labeled runout/datum pack and the clearer estimate path.
What widens bands fastest
Unlabeled mix of concentricity and runout, datum A that only exists after a later grind, 100% CMM of every diameter called concentric, and keyway timing notes that conflict with the datum scheme. Quantity breaks help unit minutes but do not erase inspection risk—see [how quantity breaks change CNC unit cost](https://3dwk.com/resources/how-quantity-breaks-change-cnc-unit-cost) and [what needs_manual means](https://3dwk.com/resources/what-needs-manual-means-preliminary-quote).
What to do next
Mark **RUNOUT** (circular or total) with size and datum, reserve **CONCENTRICITY** only when the acceptance plan truly needs it, then upload on [quote-new.php](https://3dwk.com/quote-new.php). Service pages: [CNC machining](https://3dwk.com/cnc-machining-service.php), [materials](https://3dwk.com/materials.php). Treat **rates.v1.1** min/mid/max as estimates, not invoices. If the UI shows **needs_manual**, answer the datum/runout questions rather than forcing a fake firm price.
Common questions
Is runout always cheaper to quote than concentricity?
Often yes under **rates.v1.1** estimates, because shop verification maps to dial or roundness checks more cleanly. Concentricity can still be correct—just expect heavier inspection packaging.
Can I write “concentric or runout OK”?
Avoid it. Estimators cannot pick an inspection family from that note. Pick one control per feature family.
How do grind ops change the callout?
Name whether runout applies as-turned or after grind, and whether datum A is re-established. Silent stage notes widen bands.
Do keyways follow the same habit?
Yes. Keyway position relative to a runout datum is a sibling topic—see [keyway callouts on CNC turned shafts](https://3dwk.com/resources/keyway-callouts-on-cnc-turned-shafts)—but journal runout vs concentricity remains mandatory on production shaft RFQs.