CAD services — production, conversion and standards, at project scale.

What CAD production looks like when it is done properly

CAD stopped being a drawing tool a long time ago. On a live project it is a database of geometry that hundreds of people read, mark up, cut sections through and hand to a subcontractor two years later. Whether that database is usable is decided by the parts nobody sees: layers, blocks, references and the discipline behind them.

Production work covers:

• Structural, architectural and civil drawing production from designer sketches, calculations, markups or models.
• Sheet set management — title blocks with populated fields, consistent scales, key plans, north points and drawing numbering that follows the project convention.
• Layer, block and reference discipline — external references bound or resolved deliberately, blocks from a controlled library, no orphaned or duplicated definitions.
• Plot and publish setup, so what leaves the office looks the same on every machine that opens it.
• Detail libraries built once, versioned, and reused across the set rather than copied and quietly edited.

Conversion, legacy sets and drawing archaeology

A large part of real CAD work is not new drawing. It is making an old set usable: PDF or scanned drawings rebuilt as editable, correctly scaled CAD; hand drawings redrawn; several generations of amendments consolidated into one current set; site markups turned into as-built records.

The work is done properly rather than traced. Scales and units are verified against known dimensions rather than assumed. Layers are rebuilt to the current standard instead of inherited from whatever the original used. Where the source is ambiguous — a dimension that does not agree with the geometry, a detail referenced on a sheet that no longer exists — it is raised as a query rather than resolved silently, because a confident wrong answer in a legacy set survives for decades.

Point cloud to CAD belongs in the same category. A registered scan is turned into 2D plans, sections and elevations at a stated tolerance, with the deviation between the cloud and the drawn line recorded rather than flattened — so a survey that says a wall leans forty millimetres over its height produces a drawing that says so too.

What you get back is a set someone can work in, with a note of every assumption made to produce it.

Model to 2D, and keeping the two in step

Most projects now live in both worlds: a model that holds the geometry and a 2D set that people actually build from. The failure mode is well known — the model moves, the drawings do not, and by the third revision nobody trusts either.

We produce 2D output directly from Revit, Tekla or Advance Steel models, with view templates, annotation standards and drawing conventions applied consistently, then reconcile the issued sheets against the model revision they were cut from. Where the project has to hand DWG to a party working outside the model, the export is set up once, checked, and repeated identically rather than improvised per issue.

Manufacturing drawings, not only construction drawings

Plenty of what a construction project has to draw is not a building. Equipment supports and skids, bespoke brackets, plant guarding, tank and vessel ancillaries, ductwork transitions, architectural metalwork and one-off fabricated items are all manufacturing drawings, and they are read by a machine shop rather than by a site engineer. The conventions are different and so is the tolerance thinking.

That work covers assembly and exploded-view drawings with a parts list that agrees with the assembly, sheet metal development including flat patterns with the bend allowance stated for the material and tooling, complex surface geometry where a form has to be described rather than dimensioned, and geometric dimensioning and tolerancing applied to ASME Y14.5 or to the ISO GPS system with ISO 1101, whichever the shop reads.

The distinction that matters is between a dimension and a requirement. A construction drawing can often say what it wants and let the trade resolve it; a manufacturing drawing has to say what is controlled, from which datum, and to what tolerance, or the part is made twice. Part numbering, revision control and the bill of materials are set up to match the manufacturer's system rather than the project's, because that is who will consume them.

Standards, naming and the CAD manual nobody reads

Every client has a CAD manual. Most of them are enforced by whoever happens to check the drawing. We enforce them automatically instead.

We work to your manual where you have one, and to the recognised conventions where you do not: ISO 19650 information container naming for projects running a formal common data environment, the legacy BS 1192 layer conventions still in use across much of the United Kingdom, the AIA CAD layer guidelines common in North America, ISO 13567 where CAD layers are organised to an international scheme rather than a house one, and ISO 128 and ISO 7200 for drawing presentation and title block data. Where the sheet is a manufacturing drawing, BS 8888 governs technical product documentation in the United Kingdom, with ASME Y14.5 or ISO 1101 for the tolerancing on it.

The point is not conformance for its own sake. It is that a consistent set can be searched, filtered, plotted and handed over as an asset record, and an inconsistent one has to be reworked by whoever inherits it.

Machine-checked drawing sets

Automated checks run over the whole set before issue, not sheet by sheet at review:

• layers, line types, text styles and dimension styles against the project standard;
• external references resolved, with no missing or circular references and no unintended nesting;
• dimensions that are text overrides — the single most dangerous defect in a CAD set — flagged wherever they appear;
• scale consistency between viewport, annotation and stated scale;
• title block fields populated, including revision, status, scale and originator;
• drawing numbers unique, and the issued set reconciled against the drawing register;
• cross-references that point at sheets and details that actually exist.

The results go to the reviewer with the drawings. A senior engineer reviews and signs the issue, and the check record goes into the register with it.

How the work runs, and what you receive

Intake fixes the standard, the template, the numbering convention and the issue programme. Production runs against a register with a drawing-by-drawing programme, so progress is a count of drawings at a status rather than a percentage someone estimated.

Deliverables are DWG in the version your project uses, PDF issue sets, the drawing register, and the check record. Where the work feeds detailing or modelling, the CAD output is built so that the next stage can consume it rather than redraw it. BuildTwin produces the set, checks it and signs it: one delivery lead, one register, one company answerable for the sheet — not a pool of people you have to manage.