CAD pre-production, locked.
Also called: Design for manufacture · DFM pass · Production-ready CAD · Pre-release model freeze
Tuning the CAD so the actual process can make it, then locking the final models the maker builds from.
Your design model and the model a factory can make are rarely the same file. Pre-production CAD reworks geometry to suit the real process, allows for how the material behaves, then freezes the dataset. Skip it and the maker improvises on your behalf, which never ends well.
What CAD pre-production is
A model that looks finished on your screen is not the same as a model a factory can make. Pre-production CAD is the pass that closes that gap. You take the design-intent geometry and rework it until it suits the actual process that will produce it, the actual material that will fill it, and the actual person who will tool it. Then you lock it, so nobody downstream is guessing what you meant.
The systems-thinking part is this: a feature is never just a feature. A wall thickness is a cooling rate. A sharp internal corner is a crack waiting for the first kiln cycle. A vertical face with no taper is a part that fights its own mould on the way out. Every line you draw in CAD has a consequence three buildings away, in a workshop you have never visited, and pre-production is where you trace those consequences before they cost money.
The discipline is unglamorous and it pays for itself every time. The alternative, in my experience, is a tool that needs recutting, a first batch that cracks, and a four-week slip while everyone argues about whose fault it was.
Notice every row is a translation. The design said one thing; the process needed it said differently. Pre-production is where the translation gets done by you, on purpose, rather than by a maker, under pressure, at the bench.
- Send the design-intent file and assume the maker will sort the rest.
- No draft, no shrinkage, sharp corners the kiln will crack.
- Tolerances copied from the design, none the process can hold.
- Live, unlocked files that quietly drift between quote and build.
- Geometry reworked to suit the real process before it ships.
- Draft and uniform walls in; thin, crack-prone spans out.
- Shrinkage allowed for, tolerances set to what the process holds.
- Final models versioned, locked, and released for build.
How it fits the bigger picture
CAD pre-production is activity 07.10.11 in the framework, near the close of Stage 07 Engineer. It takes the finished engineering models and makes them buildable. Once the maker has a clean dataset and starts producing, the next activity, record iterations & developments (07.10.12), captures every change the real build forces, so the locked models and the reality on the bench never drift apart.
What it can do
It turns a design that is right into a design that is makeable, by the specific process and the specific maker in front of you. It catches the cracked first batch, the recut tool, and the four-week slip before any of them happen, while they are still free to fix in CAD.
What it can’t do
It can’t rescue a design that was wrong upstream; a beautifully manufacturable bad product is still a bad product. And it can’t freeze reality. The first real build will still surprise you, which is exactly why record iterations & developments sits right behind it to catch what the freeze missed.
See the full 10-stage process →
Try it yourself
Open your finished design model and ask the question a maker would ask: “how would I actually make this?” Walk the geometry feature by feature against the real process, fix what it can’t produce, allow for how the material behaves, then version and lock the result. Hand over a released revision, not a working file. If you don’t know your process well enough to do this, that gap is the finding.
Want a guided run at getting a product production-ready? Start the Free Sprint → and the GPT will walk you through it.
Your pre-production checklist
Project notes: the maker who phoned about the corners
▸ From the notebook · optional reading
Getting the proofing box’s ceramic shell ready for the Stoke-on-Trent maker, and the late change that nearly cracked the whole first batch.
3 min read · click to open
The shell looked done. It rendered beautifully and Dan and Anna loved it. But “done as a design” and “done for a kiln” are different sentences, so before anything went to Stoke-on-Trent we did the pre-production pass.
What the process demanded
Ceramic casting wants draft on every vertical face, or the part fights the mould coming out. It wants a uniform wall, or thick sections and thin sections cool at different rates and the thin ones crack. And the clay shrinks in the kiln, so the model has to be drawn deliberately oversized to land on the dimension the lid and the PCB carrier actually needed. We worked through the geometry feature by feature and reworked all three.
The late change, and the ripple
Then, with the freeze almost done, Anna asked for a tighter radius on the top edge, purely for looks. Small request. On the screen it was two minutes of work. I asked the Stoke-on-Trent maker before touching it, and he phoned straight back: that radius put a near-sharp internal corner right where the wall was already at its thinnest. “That’ll crack on the first firing, every time.” A two-minute CAD edit would have written off the entire first batch four weeks later, in a kiln two hours up the road, and nobody on our side would have known why.
We kept a softened version of the radius that the maker was happy with, fattened the wall locally to carry it, and only then froze the model. That is the whole point of pre-production: the cost of a change climbs the further down the line it lands, and CAD is the cheapest place on the line.
The handoff
Final models versioned and marked released. The ceramic dataset went to Stoke-on-Trent, the board files to the Manchester PCB house, each at the revision they had signed off, with the simplified PCB mounting that made assembly a single fixed seat rather than a fiddle. UKCA and BS EN 61010 work sat on top of a dataset that was, finally, frozen. The first batch came out of the kiln intact.
— Engineer stage, project notes, 2026
— Next in Engineer → Record iterations & developments