2D Engineering Drawings Paired with 3D CAD Models

Why public CAD corpora rarely give you drawing-model pairs

Public CAD datasets mostly contain geometry without the released drawings a manufacturer actually signed off. The ABC dataset collected about a million CAD models for geometric deep learning, but it holds B-rep and mesh geometry, not dimensioned drawing sheets [1]. The Fusion 360 Gallery records sketch-and-extrude construction sequences for reconstruction, which is useful for sequence models but again carries no GD&T-annotated drawings [2].

Drawing benchmarks have the opposite gap. MechVQA is a mechanical-drawing question-answering benchmark built through a semi-automated construction and quality-control pipeline, not a conversion-to-solid dataset [3]. Text-to-CAD sets such as Text2CAD pair geometry with prompts rather than with drawings [4]; see text-to-CAD training data for that pairing.

The result is that a team converting a legacy archive of scanned D-size sheets into parametric models usually has to license pairs from companies whose engineering departments produced both artifacts under change control. That is the gap this page addresses; drawing OCR and annotation alone belong to engineering drawing annotation data.

What a training pair should contain

A training pair is the released drawing, the native or neutral model it documents, and a manifest that proves they describe the same part at the same revision. Specify each component explicitly, because suppliers will otherwise send whatever export is easiest.

• Drawing side: the vector source where it exists (native drawing file, DWG/DXF or vector PDF) plus a raster at a stated DPI for scanned legacy sheets. Keep all sheets, including section views, detail views and the parts list.
• Model side: the native part or assembly (SolidWorks, Creo, NX, Inventor, CATIA or Onshape exports) and a neutral STEP file, ideally AP242 so product manufacturing information can travel with the geometry. Ask whether the feature tree survives export or only the B-rep.
• Annotations: dimensions, tolerances, datum feature symbols and feature control frames per ASME Y14.5 [5], surface finish symbols, weld symbols, general notes and the revision block. Views alone teach shape; annotations teach intent and are what consistency checkers need.
• Manifest fields: part number, drawing number, drawing revision, model revision, PDM state (for example Released, Superseded, Obsolete), ECO or ECN number, CAD system and version, units, sheet size, projection angle (first or third angle) and whether the model was authored first or rebuilt from the drawing.

That last field matters more than most buyers expect. A model authored first and detailed into a drawing teaches forward documentation, while a model rebuilt from a legacy sheet by a drafter teaches exactly the conversion task you want to automate, including the drafter's interpretation choices.

Revision alignment is the main failure mode

The most common defect in drawing-model pairs is a revision mismatch, where the sheet documents one revision and the model file reflects another. In many shops, models are revised in PDM ahead of the drawing release, or a drawing is red-lined on paper and never fed back to the model; treat this as a working hypothesis to test in every sample, not as a known rate.

Concrete checks catch most of it. Compare the revision letter in the title block with the PDM revision of the model, confirm the ECO referenced in the revision table exists in the change history, and render the model in the drawing's projection to compare silhouettes against the drawing views. A dimension-level check, measuring the model at each dimensioned feature and comparing to the nominal on the sheet, catches subtler drift such as a hole moved in the model but not on the drawing.

Decide up front what you do with mismatches. For a conversion model, mismatched pairs are label noise and should be dropped or quarantined. For a drawing-model consistency checker, a labeled set of real mismatches with the ECO that caused them is valuable negative data, so ask suppliers to keep and flag them rather than silently remove them.

Illustrative example: invented to show structure; it does not describe an available dataset.

De-identifying title blocks and drawing content

Title blocks and notes carry the identities a supplier is least willing to release, so de-identification has to cover drawing text, model metadata and file names together. A typical title block names the supplying company, often the end customer, the drafter, checker and approver initials, a CAGE code, drawing and part numbers and sometimes a contract number.

Treat the drawing as an image and as text. Redact or replace title-block cells and customer-specific notes in the vector source, then regenerate the raster so no hidden layers or PDF annotation objects carry the original values. On the model side, scrub file properties, custom properties, author fields and assembly component names, and check STEP header fields such as FILE_NAME and author strings, which frequently preserve original paths and user names.

Keep part and drawing numbers as consistent tokens rather than deleting them, because the model needs the join key and your revision checks depend on it. Redaction itself changes the training distribution: a model trained only on blanked title blocks may learn that title blocks are empty. Ask for a consistent synthetic fill rather than black boxes if title-block reading is part of your task. The SourceX guide on de-identifying CAD and engineering drawings covers the method in more depth, and multimodal de-identification covers images and metadata in combination.

Export control and contract restrictions on engineering drawings

Engineering drawings are among the records most likely to be export-controlled, so every pair needs a classification decision before it leaves the supplier. As of October 2026, under ITAR, technical data includes information required for the design, development, production or manufacture of defense articles, including blueprints and drawings [6]. Under the EAR, releasing controlled technology to a foreign person inside the United States can count as an export to that person's country, which matters if your annotation or ML team includes foreign nationals [7].

Ask suppliers to exclude drawings flagged ITAR or with an ECCN other than EAR99 unless your own export counsel has approved the handling. Also exclude designs made under customer contracts that restrict reuse of drawings, and drawings marked proprietary to a customer rather than the supplier. Distribution statements, CUI markings and "property of" legends on the sheet are strong signals to pull a record. The export-controlled technical data guide lays out the ITAR and EAR checks in more detail.

This page is general information, not legal advice. Confirm requirements with counsel for your jurisdiction and use case.

Choosing pairs for conversion, consistency checking and copilots

Different applications need different slices of the same archive, so state your task before you request data. A pair that is ideal for one model can be noise for another.

Diversity across suppliers matters more than raw volume for conversion work. Drafting conventions vary by company, era and CAD system: first versus third angle projection, pre-Y14.5-2018 symbology, hand-lettered notes and stamped revisions on older sheets. A model trained on one company's template will often fail on another's title block and view layout. For held-out sets, see private multimodal evaluation sets.

Request template for a drawing-to-CAD dataset

A good request describes the data, the alignment rules and the exclusions, not the companies you hope will hold it. You can adapt the multimodal dataset specification template or start from this outline.

Illustrative example: invented to show structure; it does not describe an available dataset.

1. Task: convert scanned 2D mechanical part drawings into parametric 3D models; secondary task flags drawing-model inconsistencies.
2. Domain: machined and sheet-metal parts; assemblies out of scope initially.
3. Drawing format: vector PDF or DWG where available; scans at a stated minimum DPI; all sheets.
4. Model format: native files plus STEP AP242; feature tree preferred.
5. Alignment: part number and revision must match; mismatches retained only with a flag and ECO reference.
6. Annotations: GD&T per Y14.5 retained; notes and revision tables retained.
7. De-identification: title-block names, customer references, CAGE codes and file metadata replaced with consistent tokens.
8. Exclusions: ITAR, non-EAR99 ECCNs, customer-owned designs, CUI or distribution-limited drawings.
9. Allowed use: training and evaluation of conversion and checking models; state whether derivative weights may be deployed commercially.
10. Sample: a small set of pairs for alignment and redaction review before any larger scope.

Licensing these records can involve more than one rightsholder, for example a supplier that drew a part to its customer's design. The guide to licensing multimodal records from several rightsholders covers how to ask who owns each side of the pair.

How SourceX approaches drawing and CAD pairs

SourceX sources operational datasets from US companies, including engineering records and documents, and manages the licensing and ongoing purchases. Drawing and model pairs are sourced on request rather than held in stock, and a request does not guarantee a match. Buyers describe the data; SourceX looks for US businesses that hold it, and every release is approved by the supplying company.

Each dataset is rights-reviewed for ownership and consents and delivered under a license that defines the records, uses, term and delivery. Personal details such as names and emails are removed or replaced before delivery, the method is recorded and a sample is checked, though no method is perfect. Delivery runs through private, access-controlled workflows only after an executed agreement and supplier approval. You can describe the drawing and model pairs you need at any stage of scoping. Related owner pages cover CAD and PCB design datasets and licensing CAD and engineering drawings, and the multimodal data hub maps adjacent pairings.

Source drawing-to-CAD training pairs

If you are building drawing-to-CAD conversion or consistency checking, send SourceX a description of the parts, formats, alignment rules and exclusions you need. SourceX assesses data and licensing permissions with suppliers, and nothing is contracted until a supplier agrees. Start a buyer request.