The short answer
On a CNC production RFQ, **soft jaws** and a **standard hard vise** are not the same quote package. Soft jaws can nest irregular envelopes, protect finished faces, and share a fixture plate across a lot. A hard vise keeps changeovers simple for prismatic blanks and often wins when jaw cutting or scrap isolation outweighs nesting savings. Silence on workholding intent is what widens many [quote-new.php](https://3dwk.com/quote-new.php) **rates.v1.1** estimate bands—not the blank size alone.
This guide is for buyers packaging prismatic aluminum production RFQs. Illustrations use an **Example part** only—not a customer fixture. Related lot and holding notes live in [nest vs one-up CNC production lots](https://3dwk.com/resources/nest-vs-one-up-cnc-production-lots), [how workholding changes a CNC quote](https://3dwk.com/resources/how-workholding-changes-cnc-quote), and [prototype vs production CNC quotes](https://3dwk.com/resources/prototype-vs-production-cnc-quotes); here we focus on **how to label soft-jaw vs vise intent** so estimators do not guess.
What soft jaws and hard vises mean for quoting
A hard vise clamps stock between fixed jaws—fast for square or rectangular blanks with parallel faces. Soft jaws are machined (often aluminum) to the part profile so clamp pressure lands on non-critical features and locating is repeatable across a lot. Process pages for automotive and automation aluminum ([CNC 3-axis Al 6061 automotive](https://3dwk.com/en/cnc-3axis/al-6061/automotive.html), [CNC 5-axis Al 6061 automotive](https://3dwk.com/en/cnc-5axis/al-6061/automotive.html), [CNC turning Al 6061 automotive](https://3dwk.com/en/cnc-turning/al-6061/automotive.html)) assume clear workholding notes when lots mix finished faces and secondary ops.
Do not bury “hold somehow” inside a notes cloud. Put **VISE OK** or **SOFT JAWS REQUIRED** (plus which faces may be clamped) 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).
Fixture minutes, jaw cut and plate share
Soft jaws add a first-article fixture cut: machine time for jaw pockets, plus programming and prove-out. That cost amortizes across the lot under **rates.v1.1** estimates; it rarely pays at qty 1–3 unless the geometry cannot be held otherwise. Hard vise setups skip jaw cutting but may need extra ops, tape/pads, or hand load that raise piece minutes. Soft stock (PA66 time coeff ×0.8) still needs clamp faces that will not crush. Harder alloys (17-4PH ×1.4, IN718/IN625 ×2.5) amplify jaw wear and heat; aggressive soft-jaw asks on hot alloys frequently auto-route toward **needs_manual** when mid-line bands exceed planning thresholds.
If the lot can share a fixture plate with nest rules, say so—see [nest vs one-up CNC production lots](https://3dwk.com/resources/nest-vs-one-up-cnc-production-lots). If each piece must be one-up for FAI or serial control, say **ONE-UP + VISE** explicitly.
Bar $/kg planning bands (estimates only): PA66 ~5, 17-4PH ~9, IN718 ~55. Material cost is rarely the workholding story—fixture minutes and scrap isolation are.
Finished faces and clamp keep-outs
Cosmetic anodize faces, sealing lands, and thin walls hate vise serrations. Soft jaws can leave clearance around those features; hard vises need pads, tape, or a different op order. Name clamp keep-outs the same way you name support keep-outs on AM RFQs. Related: [as-machined before Type II anodize](https://3dwk.com/resources/as-machined-before-type-ii-anodize), [minimum wall CNC vs SLM for buyers](https://3dwk.com/resources/minimum-wall-cnc-vs-slm-for-buyers).
Tolerance and inspection traps
Tight true position after a soft-jaw re-clamp can fight datum transfer if jaws are cut from a different blank than the lot. Default non-critical envelope to ISO 2768-m and put functional tolerances only on locating or sealing features. Related: [datum schemes for multi-setup CNC parts](https://3dwk.com/resources/datum-schemes-for-multi-setup-cnc-parts), [GD&T callouts that raise CNC quote bands](https://3dwk.com/resources/gdandt-callouts-that-raise-cnc-quote-bands), [CMM sampling plans for CNC lots](https://3dwk.com/resources/cmm-sampling-plans-for-cnc-lots).
Illustration 1 shows an **Example part** with labeled soft-jaw profile clamps versus a hard-vise parallel grip on the same blank envelope.
Example part walkthrough
**Example part:** 6061-T6 plate ~150×90×20 mm, two finished side faces for Type II later, one locating boss Ø20, ISO 2768-m general, boss true position 0.1 to Datum A. Lot qty 40. With STEP + **SOFT JAWS — clamp on stock pads only; keep finished faces clear**, expect a usable automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same geometry with silent CAD and “hold somehow / cheapest fixture” often lands DFM notes or **needs_manual**—without inventing any customer PO.
Illustration 2 contrasts a vague RFQ (“use soft jaws if needed”) versus a labeled soft-jaw / vise block and the clearer estimate path.
What widens bands fastest
Unlabeled mix of soft-jaw and vise asks, “protect all faces” without clamp pads, conflicting nest rules next to soft jaws, and 100% CMM of every clamp witness. Quantity breaks help unit fixture cost but do not erase keep-out 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 **VISE OK** or **SOFT JAWS REQUIRED**, name clamp keep-outs and lot strategy, 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 workholding questions rather than forcing a fake firm price.
Common questions
Do soft jaws always lower unit cost at qty 50+?
Not always. Jaw cutting and prove-out must amortize. Simple prismatic blanks often stay cheaper in a hard vise even at higher qty under **rates.v1.1** estimates.
Can I soft-jaw every prototype?
Usually no. Soft-jaw cutting can exceed the part minutes at qty 1–2. Prefer vise or modular clamps unless geometry forces a profile grip.
How do anodize faces change the choice?
Keep finished / anodize faces out of serrated jaws. Soft jaws or pads reduce witness marks that widen finish quotes—see [how anodize choice changes CNC RFQ cost](https://3dwk.com/resources/how-anodize-choice-changes-cnc-rfq-cost).
Should nest rules follow the same labeling habit?
Yes. Soft jaws and nesting interact—see [nest vs one-up CNC production lots](https://3dwk.com/resources/nest-vs-one-up-cnc-production-lots)—but vise vs soft-jaw remains mandatory on production RFQs.