Straight
Answers.
No fluff. If your question isn't here, contact us and we'll add it.
The Basics
What CADdition is, who it's for, and what you get.
What is CADdition?
A parametric drawing engine. Designers publish models. You enter your dimensions. CADdition produces a complete A4 PDF drawing pack: four orthographic views, dimension lines, a cut list, and a bill of materials. No CAD software. No engineering degree.
Do I need to install anything?
No. CADdition runs entirely in your browser. Enter dimensions, preview in 3D, download a PDF. No installation, no licence, no plugins.
What do I get in a drawing pack?
Four A4 sheets: front elevation, side elevation, top view, and isometric. Each sheet includes dimension lines, extension lines, and a title block. The pack also includes a cut list (part lengths, sections, quantities) and a bill of materials grouped by assembly.
Can I Actually Use These?
The questions you're really asking before you take drawings to the workshop.
How accurate are the drawings?
Dimensions are computed to sub-millimetre precision from your inputs. All views are orthographically projected from a true 3D solid using CadQuery, the same OCCT geometry kernel used in FreeCAD and professional CAD tools. This is computed geometry, not a sketch.
Can I use these drawings for real fabrication?
Yes. The drawings are production-ready. Dimensions are in millimetres. The cut list tells you exactly what to cut and how many. Print the PDF at A4 landscape and hand it to your fabricator.
My project is custom. Will a model fit my dimensions?
Every model is fully parametric. Enter your actual site dimensions (opening width, post height, tube sizes) and the engine recomputes everything: geometry, dimension lines, cut list, BOM. It's not a template you stretch. It's a computation from your numbers.
What if a dimension in the drawing is wrong?
Change the input, regenerate. Drawings take under sixty seconds. There's no waiting on a drafter. If you entered the wrong number, fix it and go again.
What Does It Cost?
The short answer: nothing to start, and no surprises.
Is CADdition really free?
The Free tier gives you 5 drawings per month with watermarked PDFs. No credit card. No trial that expires. Free forever.
What does Pro add?
Pro removes watermarks, increases the monthly limit, and adds priority support. See the pricing page for current plans. The models themselves are the same on every tier.
Do I own the drawings I generate?
Yes. The PDF output is yours. Print it, email it, hand it to your fabricator. CADdition doesn't claim ownership of your generated drawings.
What Can I Build?
What's available now, and what's coming.
What products are available?
The catalogue features community-designed parametric models and is growing. New product types are being added by community designers. Check the catalogue for the latest list.
Can I request a new model type?
Yes. If you need a specific product type and it doesn't exist yet, let us know. Community designers can also build models for any product category.
What file formats do I get?
A4 PDF is the primary output. Models with a build_assembly() function also support STEP export for import into CAD software. SVG output is available in the browser preview.
Building Models
For engineers and designers who want to publish parametric models.
Can I create my own models?
Yes. Write a JSON manifest describing your parameters and a Python build script using CadQuery. CADdition handles the configurator UI, 3D preview, orthographic projection, and PDF export.
What language are models written in?
Python with CadQuery for geometry. The manifest is JSON. You write two files: a manifest describing parameters, defaults, and validation rules, and a build script that takes those parameters and returns 3D geometry. No frontend code needed.
How do I publish a model?
CADdition runs an AST safety check and sandboxed test execution before publishing. Once live, your model appears in the catalogue for anyone to use.
What CadQuery features can I use?
Most of CadQuery: boxes, cylinders, extrusions, lofts, sweeps, booleans, chamfers, fillets, holes, shells, transforms. You can also import math. See the full allowed/blocked list in the model creation guide.
Are there limits on model execution?
Yes. Models run in a sandboxed subprocess with a 15-second CPU timeout, 256 MB memory limit, and 10 MB output limit. Most models complete in under 2 seconds.
Can I add dimension lines to my model's drawings?
Yes. Return a v2 dict from build() with "primitives" and "dimensions" keys. The SDK provides dim(), angle_dim(), radius_dim(), diameter_dim(), leader_note(), and ordinate_dim() functions. See the model creation guide for details.
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