DFM checklist before an online CNC quote

The short answer

Before you hit upload on [quote-new.php](https://3dwk.com/quote-new.php), run a short **DFM checklist** on the CAD and drawing pack. Most preliminary range problems are not “the price engine is wrong”—they are missing material condition, ambiguous datums, cosmetic callouts on every face, or geometry the automatic parser cannot treat as a single CNC setup. Fix those first so the **rates.v1.1** estimate band is useful.

This guide is for buyers preparing an **online CNC quote**. Illustrations use an **Example part** only—not a customer case.

Why DFM before upload beats re-quoting later

Online estimates parse STEP (and notes from your PDF when provided). Thin walls, deep pockets, nonstandard threads, and “machine everything tight” notes widen the band or flip the line to **needs_manual**. A ten-minute CAD cleanup often beats a day of email clarification. Related buyer context: [CNC cost drivers](https://3dwk.com/resources/cnc-machining-cost-drivers-buyer-guide), [pockets / thin walls / undercuts](https://3dwk.com/resources/cnc-pockets-thin-walls-undercuts), [reading a preliminary quote](https://3dwk.com/resources/reading-preliminary-online-quote-min-mid-max).

File pack checklist

• Native or neutral solid: STEP preferred for CNC parse
• Dimensioned PDF with datums A–B–C (or clearly stated primary faces)
• Material + temper / heat-treat condition (not just “stainless” or “aluminum”)
• Quantity and need-by window
• Finish list only where functional (anodize, passivate, bead blast—not “make it pretty”)
• Threads called as standard sizes with depth; note if inserts are allowed

Incomplete packs still upload; they just produce wider bands or manual review.

Geometry hygiene for automatic CNC quotes

**Walls and ribs:** keep aluminum walls near shop-comfortable thickness for the envelope; knife edges and 0.5 mm cosmetic walls inflate risk notes. **Corners:** internal vertical corners need cutter radius—do not model sharp internal 90° as if a mold. **Pockets:** depth-to-diameter ratios that look like EDM cavities often leave CNC auto ranges shaky. **Undercuts:** if the part needs side action or 5-axis reach, say so; otherwise the engine may assume multi-setup 3-axis.

Illustration 1 shows a pre-upload DFM gate for an **Example part** housing: walls, corners, threads, finish scope.

Tolerance discipline (what to tighten)

Default many features to a general tolerance such as ISO 2768-m (or your company equivalent). Tighten only mates: bearing bores, sealing flats, dowel patterns. Blanket ±0.01 mm on every edge forces conservative time and inspection assumptions in estimate logic. See [GD&T basics for buyers](https://3dwk.com/resources/gdt-basics-for-buyers) and [surface roughness Ra](https://3dwk.com/resources/surface-roughness-ra-for-machined-parts).

Material and process pairing

State alloy and condition that match the process you want priced:

• CNC bar stock for prismatic parts (e.g. 6061-T6, 17-4PH annealed→age sequence)
• SLM + machine datums only when geometry truly needs additive

**rates.v1.1** planning bands (estimates, not invoices): bar $/kg examples include PA66 ~5, 17-4PH ~9, IN718 ~55, IN625 ~60; CNC machine-time coefficients include PA66 ×0.8, 17-4PH ×1.4, IN718/IN625 ×2.5, CoCr ×2.2; 17-4PH H900/H1025 heat treat often ~+$60/lot when selected. Hot alloys and CoCr lines above configured USD thresholds auto-route to **needs_manual**.

Finish callouts that change quotes

Anodize Type II vs Type III, hardcoat masking, and “anodize then cut threads” sequences change both process steps and inspection. If finish is TBD, say so—do not invent a Class 2 black callout you do not need. Cosmetics on every pocket floor rarely belong on a prototype RFQ.

Threads, inserts and hardware

Call standard metric/UNC where possible. Note if helical inserts or press inserts are acceptable in aluminum bosses. Blind holes need usable tap depth called on the PDF. Ambiguous “M4 everywhere” without depth invites manual questions.

Setup and axis assumptions

Ask yourself: can this **Example part** be held in a few 3-axis setups, or do angled ports force 3+2 / 5-axis? Buyers who over-specify continuous 5-axis when positional indexing is enough pay for machine class they do not need. Background: [3-axis vs 5-axis for buyers](https://3dwk.com/resources/3-axis-vs-5-axis-cnc-for-buyers), [five-axis aluminum housing tips](https://3dwk.com/resources/five-axis-aluminum-housing-design-tips).

Illustration 2 contrasts a vague upload versus a checklist-complete pack and the resulting estimate path (auto min/mid/max vs needs_manual).

Quantity and revision hygiene

Prototype qty 1–5 with revision A is fine. Do not upload Rev C geometry while the PDF still says Rev A. Changing the STEP after you saved a mid estimate means re-parse—do not paste last week’s mid onto a revised model.

Example part walkthrough

**Example part:** 6061-T6 cover, ~120×80×25 mm, ISO 2768-m, four M4 through, one sealing face Ra 1.6, clear Type II anodize optional. With STEP + PDF datums, you should expect an automatic planning band on [quote-new.php](https://3dwk.com/quote-new.php). Same envelope modeled with 0.4 mm walls, sharp internal corners, and “±0.01 all over” often lands in DFM notes or manual review—without inventing any customer PO.

What to do next

Run the checklist, 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). If the UI shows needs_manual, answer the notes rather than forcing a fake firm price.

Common questions