No drawings for an old or discontinued part? Here's how reverse engineering and 3D scanning turn a physical part into an accurate, editable CAD model.
You've got the part in your hand. What you don't have is a drawing, a model, a spec sheet, or anyone left who remembers who made it. This is normal with legacy equipment, discontinued OEM components, parts inherited through an acquisition, or anything old enough that whoever designed it retired years ago. You still need a CAD model — to modify the part, get it manufactured, run a stress check, or just document it before the last good one wears out.
That path has a name: reverse engineering. Capture the part's geometry, rebuild it as an editable CAD model, and confirm the model matches the part before you rely on it for anything critical. Here's how each step actually works.
A CAD model built to look at is not the same file as one built to manufacture from. For reference or documentation, a close visual match is enough. If a machine shop or molder is going to cut metal or fill a mold from it, every dimension that controls fit and function has to be right, and the file needs to carry tolerances, not just shape. Settling this first decides whether you need a full parametric rebuild with GD&T or something lighter — and it drives both cost and turnaround.
Manual measurement. Calipers, micrometers, pin gauges, sometimes a coordinate measuring machine (CMM). This works well on prismatic parts — brackets, plates, shafts, anything built from flat faces, cylinders, and holes. It falls apart on organic or free-form surfaces, where you're guessing at a fillet radius or a compound curve by eye.
3D scanning. Structured-light or laser scanners capture the whole outer surface as a point cloud or mesh in one pass instead of a handful of manually recorded points. This is the right call for castings, sculpted surfaces, worn or damaged parts you need to restore back to nominal, and anything too complex to measure point by point. On a rigid, non-reflective part, scanning typically holds accuracy in the low thousandths of an inch — good enough for form and fit, but a scanner can't see inside the part. Internal bores, hidden threads, and wall thickness still have to be measured directly.
Both, together. Most real parts end up here. Scan the part for its overall shape and complex surfaces, then manually measure the small number of dimensions that actually control how it mates with everything else — bore diameters, thread pitch, hole spacing — and lock those exact values into the model instead of trusting the scan mesh for them. A scan is an approximation; a bore that's off by a couple thousandths from scan noise is the difference between a part that fits and one that doesn't.
An STL or OBJ mesh is a shape — you can view it, 3D print it, or drop it into a viewer, but you can't change a fillet radius, extend a boss, or add a mounting hole the way you can in a real CAD file. A parametric solid model is a rebuilt, editable part with actual features and dimensions. If you intend to manufacture, modify, or run analysis on the part, that's the deliverable you need — say so explicitly when you scope the work, because "3D model" gets used loosely for both, and a mesh is faster and cheaper to produce.
Reverse-engineering pricing varies by shop, but the levers are consistent: part size and surface complexity, how many critical dimensions need manual verification on top of the scan, and whether the deliverable is a mesh or a full parametric solid — a parametric rebuild costs more because someone is reconstructing features by hand rather than running an automated surface fit. Simple, single-feature parts land at the low end of the market; multi-surface parts or full assemblies run well past it. It varies enough by shop and part that it's worth getting a quote against your actual part rather than a generic number. At CADmore, reverse engineering — modeling from a scan through to a finished parametric solid — typically runs $300 to $800 per part when the part is headed to 3D printing, and $800 to $1,500 per part when it's headed to injection molding or CNC machining, where tighter tolerances mean more manual verification work.
Reverse engineering — physical part to CAD — and 3D scanning are both CADmore design services. Short-range 3D scanning starts at $260, and reverse-engineering turnaround typically runs 8-10 business days. Tens of thousands of projects have been submitted through CADmore's process to date.
If the reverse-engineered model needs a physical check before you commit to a production run, CADmore builds that validation prototype in-house. Production itself is a separate step: CADmore doesn't run manufacturing, so the part goes to your own manufacturer or CADmore's partner network afterward. That split is deliberate — the reverse-engineering and DFM feedback you get is about what the part actually needs, not about steering you toward a process CADmore profits from downstream.
Send a photo and a description of what you need the model to do. Start a project, book the $100 consultation to talk through scan-vs-measure and mesh-vs-parametric before committing to either, or just get in touch with questions.
Yes — that's what reverse engineering is for. The part gets captured by 3D scanning, manual measurement, or both, then rebuilt into an editable CAD model and checked against the original before it's called done.
It depends on the geometry. Flat faces, cylinders, and holes measure fine with calipers and gauges. Curved, sculpted, or organic surfaces need a scanner — you can't caliper a compound curve accurately. Most parts end up using both: scanning for the overall shape, hand measurement for the dimensions that control fit.
A mesh (STL or OBJ) is a static shape you can view or 3D print but can't edit like a native CAD part — no feature tree, no dimensions to change. A parametric solid model is rebuilt with actual features and dimensions you can modify. If the part needs to be manufactured or changed later, ask for the parametric model specifically — a mesh alone won't do it.
3D scanning typically holds accuracy to a few thousandths of an inch on rigid, non-reflective parts, which covers form and fit for most applications. Anything actually functional — a press fit, a thread, a bearing bore — should be verified with direct measurement and locked into the model rather than left to the scan alone.
No — CADmore is a design firm, not a manufacturer. It builds prototypes in-house to validate the reverse-engineered model, but production runs through your own manufacturer or CADmore's partner network. That keeps the design and DFM feedback independent of any single production process.
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