How to Prepare STEP File for Instant Quote: 2026 Checklist

TL;DR

To prepare a STEP file for an instant CNC quote, export as AP214, use millimeters, export one part per file, unsuppress all features, validate in a free viewer, and pair the file with a PDF drawing that specifies tolerances, material grade, surface finish, and threads. Every gap in your file forces the quoting engine (or the machinist) to assume worst-case specs, which inflates your price.

Who This Is For and What It Helps You Decide

This guide is for procurement teams, maintenance managers, and engineers at Canadian industrial companies who need CNC machined replacement parts. It covers every term you’ll encounter when preparing a STEP file for instant pricing, what to fix before uploading, and what supplementary information to include so the quote is accurate the first time.

If you already have a STEP file ready, you can upload it for instant pricing right now. If you want to make sure you’re not leaving money on the table or causing delays, read on.

Section 1: Know Your Starting Point

Not every buyer starts from the same place. Before worrying about file format details, figure out which scenario describes your situation.

You have a CAD file. This is the fastest path. Export a clean STEP file, pair it with a PDF drawing, and upload for an instant quote. Most of this guide covers how to do that correctly.

You have no CAD file. Many maintenance teams working with legacy or OEM equipment have no drawings at all. This is more common than people admit. Reverse engineering from a sample part or photographs is a real option, covered in Section 6.

You have a broken part. If the part is intact enough to measure or scan, it can be reverse-engineered into a STEP file and then quoted normally.

The OEM part is unavailable or backordered. You need a replacement machined to spec. The challenge is getting the right geometry and material information together. If you have the OEM drawing, even a worn photocopy, that’s a starting point.

Lead time is urgent. A clean, complete file submission is the single biggest factor in keeping your quote automated and fast. Every missing spec bumps you into manual review, which adds days.

Material is unknown. Specifying “aluminum” instead of “6061-T6” forces the shop to guess. That guess will cost you more. If you genuinely don’t know, say so explicitly and ask for a recommendation.

Tolerance is unclear. Without tolerances, suppliers assume the tightest standards, inflating costs. Tight tolerances below ±0.005 inches can increase costs by 20-35%. Only tighten what functionally matters.

Section 2: What You Need Before Uploading

Here is everything a quoting platform needs to give you an accurate price. Missing any of these forces assumptions, and assumptions always cost more.

STEP File

STEP stands for Standard for the Exchange of Product Data, governed by ISO 10303. It is an open, vendor-neutral format that preserves full solid geometry: faces, edges, and volumes. Every CAM system and every CNC shop can read it. No special license is needed. File extensions are .stp or .step (they’re identical).

STEP is the undisputed standard for CNC quoting platforms because it carries the mathematical definition of your part, not an approximation. When you upload a STEP file for instant quoting, the platform’s algorithms analyze this geometry to estimate machine setups, spindle time, and tool requirements.

STP vs. STEP

These are the same format with two different file extensions. There is no functional difference. Use whichever your CAD system exports by default.

AP203, AP214, AP242

STEP files come in different “application protocols” that determine how much information the file carries.

AP203 handles geometry, topology, and configuration management for mechanical parts and assemblies. Think of it as the general-purpose option.

AP214 extends AP203 with colors, layers, geometric dimensioning and tolerances, surface conditions, and design intent. For most instant quoting scenarios, AP214 is the safe default.

AP242 is the newest protocol and includes everything in AP214 plus more complete Product Manufacturing Information (PMI), including surface conditions and assembly-level PMI. It’s technically superior, but not all quoting engines fully parse its extended data yet. For a deeper dive, see this STEP AP242 guide and drawing checklist.

Both AP203 and AP214 were officially withdrawn as International Standards with the publication of AP242 in 2014, but they remain universally supported by quoting platforms. Use AP214 as your default export. Use AP242 when your platform explicitly supports it.

IGES

IGES (Initial Graphics Exchange Specification) is an older neutral format. It works as a fallback when STEP export isn’t available, but it carries less geometric fidelity than STEP and can introduce surface gaps on complex parts. FrankWorks accepts IGES alongside STEP and BREP files.

BREP

BREP (Boundary Representation) files define a part by its surface boundaries. Some platforms accept BREP as a valid upload format. FrankWorks is one of them. If you’re exporting from a CAD system that defaults to BREP, it’s a usable option, though STEP remains preferred for broadest compatibility.

STL (and Why It Doesn’t Work for CNC)

STL files describe surfaces using a mesh of triangles. They’re designed for 3D printing, not CNC machining. STL files carry no parametric or feature data. When a machinist receives only an STL, they must rebuild the geometry, which increases risk and cost. Practitioners at machine shops report that STL files are one of the top causes of RFQ delays because the shop cannot generate accurate toolpaths from mesh data.

This is the number one format mistake buyers make. If your CAD system can export STEP, always choose STEP over STL for CNC quoting.

Native CAD Formats (SLDPRT, F3D, etc.)

Some quoting platforms accept native formats from SolidWorks (.sldprt), Fusion 360 (.f3d), or other software. Most do not. Converting to STEP before uploading eliminates compatibility risk and ensures the quoting engine reads your geometry correctly.

2D Technical Drawing (PDF)

Many buyers make the mistake of including only the STEP file in their quote requests. While the STEP file defines geometry, the PDF drawing controls the specs: tolerances, materials, heat treatment, surface finish, engraving, threads, finishing, and packaging. Without that information, it’s nearly impossible to provide an accurate quote.

For instant quoting platforms, the STEP file drives the automated price calculation. But for critical features, a 2D drawing prevents costly misinterpretation. Learn more about how to prepare a CAD drawing for CNC machining.

Material Grade

“Aluminum” is not a material specification. Neither is “stainless steel.” You need the exact grade: 6061-T6, 304, 4140, and so on. Material choice affects price non-linearly, with premium alloys like titanium costing 3-5× more than economical aluminum. If you don’t specify the grade, the shop either guesses conservatively (expensive) or comes back with questions (slow).

Quantity

Vague quantity descriptions like “a small amount” force suppliers to quote worst-case pricing. State the exact number. If you’re considering multiple quantities (say 1, 5, and 25 pieces), submit each scenario so you can compare per-unit cost.

Surface Finish and Ra Value

Surface finish is measured in Ra (roughness average), typically in microinches or micrometers. Standard machined finish (around Ra 125 µin / 3.2 µm) is the cheapest. Finer finishes require additional passes or secondary operations, adding cost. Specify only the finish your application actually requires.

Tolerances

General machining tolerance (typically ±0.005" or ±0.127 mm) covers most functional requirements. Tighter tolerances require slower feeds, more careful fixturing, and sometimes different equipment. The cost impact is real: 5-axis machining runs $75-120/hour versus $40/hour for 3-axis. Specify critical tolerances only on the features that need them.

For guidance on what to specify, see what it costs to manufacture one spare part in Canada.

GD&T (Geometric Dimensioning and Tolerancing)

GD&T uses standardized symbols to define feature relationships: position, flatness, concentricity, and others. It matters when parts must fit into assemblies with tight positional requirements. If your part needs GD&T callouts, put them on the PDF drawing, not in the STEP file. Most quoting engines don’t parse GD&T from 3D models.

Threads

Here’s a nuance that catches many buyers. Modelling threads in the STEP file can cause problems. One user on the Autodesk forums discovered that engravings exported to a STEP file appeared blank in the manufacturer’s system. Threads have similar issues. Best practice: represent threaded holes as simple cylinders in the 3D model and call out thread specs (M10×1.5, 1/4-20 UNC, etc.) on the PDF drawing.

Internal Corner Radius

Sharp internal corners (radius = 0) are physically impossible to machine with a standard end mill. They require EDM or extremely small tools, both of which drive up cost significantly. Design in radii of at least 0.5 mm (R0.5) where possible. Using standard tool diameters (1/8", 1/4", 3/8") for your corner radii keeps costs down because the shop doesn’t need special tooling.

Delivery Location

Shipping distance matters for lead time and cost. Some platforms add shipping as a surprise after the quote. Others include it upfront. Knowing your delivery location before you upload helps the platform calculate accurate logistics.

Photos or Sample Part (for Reverse Engineering)

If you don’t have a CAD file, clear photographs from multiple angles or the physical part itself can serve as the starting point for reverse engineering. More on this in Section 6.

Section 3: The Tradeoffs You’re Making

Preparing a STEP file for an instant quote isn’t just a technical exercise. You’re making tradeoffs that affect price, lead time, and accuracy. Understanding them puts you in control.

Faster vs. cheaper. Expedited lead times cost more. If your equipment is down, that premium is worth paying. If you’re building inventory, choose economy shipping and save.

Tight tolerance vs. higher cost. Every tolerance callout tighter than standard adds machining time. A blanket ±0.001" across all features when only two holes actually need it can inflate your quote by 20-35% for no functional reason.

One-off vs. production quantity. Setup cost is fixed regardless of quantity. One part absorbs the entire setup cost. Twenty-five parts spread it across the run. If you think you’ll need the part again, quoting a small batch now is almost always smarter. Read more about how FrankWorks compares to other Canadian MRO machining services.

Local machining vs. offshore. Canadian production eliminates cross-border delays, customs paperwork, and ITAR/EAR compliance headaches. The per-unit cost may be slightly higher, but the total cost of delays, rework, and shipping often favors local.

CAD upload vs. manual RFQ. Uploading a STEP file to an instant quoting platform takes minutes. Traditional RFQ processes, emailing shops, waiting for responses, comparing apples-to-oranges quotes, can take days or weeks. Clean files keep you on the fast path.

Reverse engineering vs. supplying a model. If you have CAD, use it. Reverse engineering adds a step and a cost. But if your only alternative is weeks of OEM backorder, that cost is trivial compared to downtime.

Section 4: Common STEP File Mistakes That Delay or Break Quotes

These are the errors that practitioners and machine shops report most frequently. Fix them before you upload and you’ll avoid the back-and-forth that kills turnaround time.

Wrong Units

A part designed in millimeters but exported in inches will be 25.4 times too small (or too large, depending on direction). Check your CAD system’s export settings. This is the most preventable and most embarrassing mistake.

Multi-Body Files

Each part should be its own STEP file. Multi-body files confuse quoting tools because the algorithms can’t determine which body is the part you want machined. Export one body, one file.

Assembly Data Left In

Export only the part body. Remove assembly references, mates, and constraints before exporting. Leftover assembly data bloats the file and can break geometry parsing.

Suppressed Features

Un-suppress all features before export. Hidden holes, pockets, and chamfers will not appear in the STEP file. The quoting engine will price a simpler part than what you actually need, and the discrepancy will surface during manufacturing, causing delays or rework.

Outdated Revisions

Name your files with the revision. Example: bracket-rev-C.stp. Shops and quoting platforms have no way to know if the file you uploaded is current. Old files cause wrong parts.

Open Geometry and Broken Surfaces

A poorly exported STEP file can contain open surfaces and geometry errors that are invisible in your native CAD environment but break the import on the quoting platform. Always open your exported STEP file in an independent viewer before sending it. Missing faces and broken surfaces slow down quotes and cause confusion.

The free NIST STEP File Analyzer and Viewer supports parts, assemblies, dimensions, and tolerances. Other free options include eDrawings (Dassault) and Autodesk Viewer, both browser-based and requiring no installation.

File Size

FrankWorks accepts files up to 50 MB. Some other platforms cap at 15 MB. If your file exceeds the limit, you’re probably exporting an assembly or carrying unnecessary data. Strip it down to the single part body.

Section 5: How FrankWorks Handles Your STEP File

When you prepare a STEP file for an instant quote and upload it to FrankWorks, here’s what happens.

The platform accepts STEP, IGES, and BREP files. Automated algorithms analyze your part’s geometry to assess manufacturability, estimate machine setups, calculate spindle time, and determine tool requirements. These systems don’t simply estimate costs. They perform comprehensive manufacturability assessments based on databases of previously machined components.

Within seconds, you see a price and a defined lead time. That price is all-in, including shipping and lift-gate delivery, with no surprise fees added at checkout. You can read more about what all-in CNC pricing includes.

The quote comes with selectable delivery speed options. You see the ship date before you commit, which matters when you’re planning around equipment downtime.

Your order is routed to vetted, Canadian-owned machine shops. Every part comes with a two-year workmanship warranty. If something isn’t right, there’s a clear rework and refund process.

The cleaner your file, the more likely your quote stays fully automated. Complex geometries, missing specs, or file errors can bump the quote into manual review, which adds time. A well-prepared STEP file is the single biggest factor in keeping the price automated and fast.

Upload your STEP file for instant pricing.

An Important Note: Instant Quote ≠ Final Price (But Clean Files Get You Closer)

Most guides treat the instant quote as the end of the story. In practice, many files trigger manual review. The gap between the initial automated price and the final price depends almost entirely on file quality and spec completeness. A STEP file with correct units, single body, proper geometry, and an accompanying PDF with tolerances, material grade, and finish specs will produce a quote that holds.

For more on what to expect from quoting terms, see quoting exclusions and shipping terms.

Section 6: When You Don’t Have a STEP File

Not having CAD shouldn’t stop you from getting a replacement part machined. Many maintenance teams working with legacy equipment, discontinued OEM parts, or equipment acquired through mergers simply don’t have drawings.

Reverse engineering is the process of recreating a part from a physical sample, photographs, or field measurements. FrankWorks offers a reverse engineering service where buyers submit photos or a sample part. The reverse engineering fee is credited if you proceed with a production order, so you’re not paying twice.

This path takes longer than uploading an existing STEP file, but it’s dramatically faster than waiting on an OEM backorder that may never arrive.

Quick-Reference Checklist: Preparing Your STEP File for Instant Quoting

Before you click “upload,” run through this list.

1. Format: STEP file, AP214 preferred. Not STL, not native CAD.
2. Units: Confirm mm or inches. Match your design intent.
3. Single body: One part per file. No assemblies, no multi-body exports.
4. Features visible: Un-suppress all holes, pockets, chamfers.
5. Geometry clean: Open in a free viewer. No missing faces or broken surfaces.
6. File size: Under 50 MB.
7. File name: Includes part name and revision (e.g., housing-rev-B.stp).
8. PDF drawing attached: Tolerances, material grade, surface finish, thread callouts.
9. Material specified: Exact grade (6061-T6, 304 SS, 4140, etc.).
10. Quantity stated: Exact number, not “a few.”
11. Delivery location known: For accurate shipping calculation.

FAQ

What file format do I need for an instant CNC quote?

STEP (.stp or .step) is the standard. It preserves full solid geometry that quoting algorithms need. FrankWorks also accepts IGES and BREP files. Avoid STL, which is mesh-based and unsuitable for CNC machining.

Which STEP application protocol should I export?

AP214 is the safest choice for instant quoting platforms. It includes geometry plus colors, layers, and basic tolerancing data. AP242 is technically superior but not all platforms fully support its extended PMI. AP203 works but carries less information.

Do I need a PDF drawing if I’m uploading a STEP file?

Yes, for anything beyond the simplest parts. The STEP file defines geometry. The PDF drawing specifies tolerances, material, surface finish, thread callouts, and any special requirements. Without it, critical specs can be misinterpreted.

Why did my instant quote get bumped to manual review?

Common triggers include broken geometry, multi-body files, missing material or tolerance specs, very complex features, and file errors. Each of these prevents the automated system from completing its analysis. Clean file preparation keeps you on the automated path.

How do tight tolerances affect my CNC quote price?

Tolerances tighter than ±0.005" can increase costs by 20-35%. They require slower feeds, more careful fixturing, and sometimes 5-axis equipment ($75-120/hour vs. $40/hour for 3-axis). Specify tight tolerances only on features that functionally require them.

What if I don’t have a CAD file for my part?

FrankWorks offers a reverse engineering service. Submit photos or a physical sample, and the engineering team will create the CAD model. The reverse engineering fee is credited toward your production order.

What’s the maximum file size for upload?

FrankWorks accepts STEP files up to 50 MB. If your file exceeds this, you’re likely exporting an assembly or carrying unnecessary data. Strip it down to a single part body.

Should I model threads in my STEP file?

No. Model threaded holes as simple cylinders in the 3D file and call out thread specifications (M10×1.5, 1/4-20 UNC, etc.) on the PDF drawing. Modelled threads can cause display errors in quoting platforms and add unnecessary complexity to toolpath generation.