ServicesScan-to-CAD

Reverse Engineering Services: From a 3D Scan to a CAD Model

Reverse engineering starts with a part that exists and no drawing of it: a worn impeller, or a casting that has to be re-made with one change. We 3D scan the part, rebuild its geometry as a CAD model, and deliver the model in STEP together with the scan it was built from. The reverse engineering services cover mechanical parts and equipment, from a few centimetres to whole machines, in every US state; the scanning is ours, and the CAD is built from that scan.

What you get

The first deliverable is the scan itself: a mesh of the part's surface in STL, which is already enough for 3D printing a replacement, for checking wear against an older part or for fitting a new component around it. The second is the CAD model, rebuilt as solid geometry in STEP, the ISO 10303-21 exchange format that CAD packages exchange, with native formats on request. The model is checked against the scan before delivery, and the features where a worn or damaged surface was deliberately restored to its design shape are listed with it. Drawings in DWG and PDF are added on request when the part is going to be made again.

How a part is scanned

Parts up to about four metres are scanned with a handheld scanner of the HandySCAN SILVER class, a metrology instrument that projects fourteen blue laser lines and is rated, by its brochure, at an accuracy of up to 0.040 mm, the brochure's typical value for diameter measurements on a calibrated sphere, with a volumetric accuracy of 0.020 mm plus 0.100 mm per metre of part under the brochure's conditions. The scanner is moved around the part by hand, in the shop or wherever the part sits, and the surface builds up on the screen as it is covered, so a missed patch is seen and filled on the spot. Its laser is class 2M and eye safe. Larger objects, a press or a section of a ship's hull, are scanned with the terrestrial scanner of the Trimble X7 class used for buildings, which holds a 3D point accuracy of 2.4 mm at 10 m (one standard deviation) by its datasheet; the two scans are combined when a machine has both a large frame and small critical features. How that scanner works is on the 3D laser scanning page; scanning parts without the CAD work is described under 3D scanning for parts and objects.

A scan records the surfaces the light reaches. Deep bores, internal passages and the inside of a closed casting are not captured, and a part that has to be reproduced inside and out is sectioned, measured with gauges at the openings or documented from its drawings where they exist; the model says which features were scanned and which were not.

Scan to CAD: mesh, surfaces and a parametric model

A mesh copies one worn part; the CAD model is the part as it was designed, and scan to CAD is the work of getting from one to the other. A bore that measures 25.06 mm on a worn part was drawn at 25 mm, and a flange that sits 0.2 degrees off square was square when it left the machine. Rebuilding the model means recovering that design intent: the datum faces are set, the standard sizes and symmetries are restored, and the free-form surfaces that have no simple description, a blade or a moulded grip, are fitted to the scan as NURBS surfaces. The list that comes with the model says, feature by feature, where the model was snapped to a nominal value and where it follows the scan.

Which features are restored and which are copied is agreed before the modeling starts, because it depends on what the part is for. A replacement that has to mate with an existing assembly keeps the measured positions of its interfaces, while a part being redesigned gets a clean model with the wear removed. The propeller guide shows the full sequence on a part that is nothing but free-form surfaces.

3D CAD and product modeling

The same modeling work is done without a scan when the part does not exist yet or exists only on paper: a CAD model built from your drawings or sketches, for a part that is being modified, quoted to a machine shop or prepared for 3D printing. Mechanical parts, fixtures, housings and simple assemblies are what this covers. Output is the same, STEP with drawings on request, and the model is built as a parametric solid that can be edited afterwards.

What reverse engineering here does not cover

The work is the geometry of mechanical parts. Software, firmware, printed circuit boards and integrated circuits are a different field that uses the same name, and they are not offered. Material analysis, hardness testing and the engineering of loads and tolerances for a redesign stay with the client's engineer; the model gives that engineer a correct starting shape. CT scanning for internal features is not offered either; the section above says what is done instead.

Price and time

Reverse engineering of a single part starts at about $1,000 for the scan and the CAD model; assemblies and large equipment are quoted on their own. The exact price comes in a quote within one business day of your sending photographs of the part, its approximate size and what the model is for. A single part is usually scanned in a day, in the shop or on site, and the model usually follows in one to two weeks. We scan in all 50 states.

Frequently asked questions about reverse engineering

What is reverse engineering with 3D scanning?

Measuring an existing part with a 3D scanner and rebuilding its geometry as a CAD model, so the part can be re-made, modified or fitted to without an original drawing. The scan gives a mesh of the surface; the CAD work turns it into a solid model with its design intent restored.

How accurate is the model?

The handheld scanner is rated at an accuracy of up to 0.040 mm by its brochure, the brochure's typical value for diameter measurements on a calibrated sphere. The CAD model is checked against the scan before delivery, and the features restored to their design shape are listed with it.

Which file formats do you deliver?

STEP for the CAD model, STL for the scanned mesh, DWG and PDF for drawings on request, and native CAD formats on request.

Can you capture internal passages and hidden features?

A surface scan captures what the laser reaches. Deep bores and internal passages are documented by sectioning the part, measuring at the openings or using existing drawings, and the model marks which features were scanned. CT scanning is not offered.

Do you reverse engineer software or circuit boards?

No. The service covers the geometry of mechanical parts and equipment only.

How much does reverse engineering cost?

A single part starts at about $1,000 for the scan and the CAD model. Assemblies and large equipment are quoted on their own. The quote arrives within one business day.

How long does it take?

A single part is usually scanned in a day and the model usually follows in one to two weeks, depending on how many features have to be rebuilt.