The short answer
On turned-shaft RFQs, a **retaining-ring groove note** is not the same as a [keyway callout](https://3dwk.com/resources/keyway-callouts-on-cnc-turned-shafts), a [shoulder fillet versus undercut](https://3dwk.com/resources/shoulder-fillet-vs-undercut-cnc-turned-shafts), or a general diameter. The groove is a narrow, square-ish ring seat—width, groove diameter, corner radius, and location from a shoulder or shaft end—measured after turning, not a “cut a snap-ring slot as needed” cloud. Silence on those four values, on whether the groove is external or internal, and on whether a slight edge break is allowed, is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate bands—not the extra seconds of a grooving pass alone.
This guide is for buyers packaging shaft RFQs where CAD shows a circlip or retaining-ring groove with only a schematic notch and no named width, groove diameter, or location. Illustrations use an **Example part** only—not a customer shaft. Sibling notes live in the [turned stainless shaft drawing guide](https://3dwk.com/resources/turned-stainless-shaft-drawing-guide) and [press-fit vs slip-fit bores](https://3dwk.com/resources/press-fit-vs-slip-fit-cnc-bores); here we focus on **ring-groove packaging** so estimators do not have to guess whether a 1.1 mm slot is a standard ring seat or an accidental undercut.
What a retaining-ring groove means for quoting
A **retaining-ring groove** is a controlled seat for an external or internal ring. It is not an O-ring gland and not a thread relief; width, groove diameter (the root), and the distance to a locating face all matter for the ring to snap and stay. Process pages for stainless turning and milling ([CNC turning SS 316 robotics](https://3dwk.com/en/cnc-turning/ss-316/robotics.html), [CNC 3-axis SS 316 robotics](https://3dwk.com/en/cnc-3axis/ss-316/robotics.html), [CNC turning SS 316 aerospace](https://3dwk.com/en/cnc-turning/ss-316/aerospace.html)) assume groove and location notes when lots mix bearing seats with snap-ring locks.
Do not bury “add a circlip groove” inside a notes cloud. Put **EXTERNAL RING GROOVE, WIDTH 1.15, GROOVE Ø18.3, CORNER R 0.2 MAX, 8.0 FROM SHOULDER A** on the PDF and mirror it in RFQ text. If you follow a named ring standard, write the standard and the ring size; do not assume a shop default. 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), [when to call out undercuts](https://3dwk.com/resources/when-to-call-out-undercuts-on-cnc-rfq).
Width, groove diameter, and location
Width that is too tight binds the ring; width that is too loose lets the ring walk. Groove diameter sets how much the ring grips; location from a shoulder or from the shaft end sets where the retained part actually sits. [Circularity vs cylindricity](https://3dwk.com/resources/circularity-vs-cylindricity-cnc-shafts) on the adjacent bearing seat is a separate note—do not let a loose groove diameter hide inside a bearing-seat tolerance. Chamfer or edge-break on the groove walls should be named if a sharp corner would crack a ring or if a large break would steal width.
Stainless 316 bar $/kg planning bands sit in the mid-commodity stainless range under **rates.v1.1** material tables; material cost is rarely the groove story—tool width, location tolerance, and adjacent-seat protection are.
External versus internal, and adjacent seats
Say whether the groove is on a shaft OD (external ring) or in a housing bore (internal ring). An internal groove needs tool access and a named bore length; an external groove must not nick an adjacent [bearing or press-fit](https://3dwk.com/resources/press-fit-vs-slip-fit-cnc-bores) diameter. If a groove sits next to a thread relief or a keyway, show the leftover land so two undercuts do not merge.
Tolerance and inspection traps
Calling “circlip groove to suit,” mixing a tight location from shoulder A with an unnamed width, or asking for 100% optical photos of every groove corner, all force **needs_manual**. Default non-critical decorative grooves to ISO 2768-m and put a functional width, groove diameter, and location only on rings that actually retain a part. Related: [ISO 2768 general tolerances on CNC RFQs](https://3dwk.com/resources/iso-2768-general-tolerances-cnc-rfq), [edge-break, chamfer and deburr callouts](https://3dwk.com/resources/edge-break-chamfer-deburr-callouts-cnc).
Illustration 1 shows an **Example part** shaft with a labeled external groove (width, groove diameter, 8 mm from shoulder A) versus a nearby groove that only needs a confirmed width for a light retaining washer.
Example part walkthrough
**Example part:** Stainless 316 turned shaft ~Ø20 × 90 mm, external retaining-ring groove width 1.15 mm, groove Ø18.3, corner R 0.2 max, 8.0 mm from shoulder A, adjacent bearing seat held separately, ISO 2768-m general. With STEP + **EXT RING GROOVE W1.15 / Ø18.3 / R0.2 MAX, 8.0 FROM SHOULDER A**, expect a usable automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with silent CAD and “add snap-ring groove as needed” often lands DFM notes or **needs_manual**—without inventing any customer PO.
Illustration 2 contrasts a vague RFQ (“circlip groove, standard size”) versus a labeled width-diameter-location pack and the clearer estimate path.
What widens bands fastest
Unlabeled “standard” grooves with no width or location, internal grooves without tool-access notes, grooves that nick an adjacent bearing seat, and 100% cosmetic inspection of every corner. Quantity breaks help unit minutes but do not erase groove ambiguity—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 each functional retaining-ring seat with **width, groove diameter, corner R, and location**, 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 groove questions rather than forcing a fake price.
Common questions
Can I just write “DIN / standard circlip groove” and skip dimensions?
Only if the standard and the ring size are named on the same view, and the CAD matches. A “standard groove” cloud with a schematic notch is not enough under **rates.v1.1** estimates. Write width, groove diameter, and location, or point to a fully identified standard.
Can the groove share a radius with a shoulder undercut?
Usually no. A seating undercut and a ring groove have different widths and diameters. Merging them silently makes both features harder to inspect. Keep a named land between them, or show one combined feature with all sizes.
How close can a groove sit to a bearing seat or a thread?
Close enough that the leftover land still protects the seat and the grooving tool does not nick it. Show the land. Leaving only the groove size leaves the estimator guessing whether a 0.5 mm leftover band is intentional.
Do I need 100% groove-width inspection?
Not as a default. Functional retaining grooves often need a first-article width, groove diameter, and location check, then a sample plan. 100% optical photos of every corner usually belong only where you have written that need.