Reverse Engineering

When reverse engineering is the right move

The classic cases: a machine still earns its keep but the company that built it is long gone; a legacy product needs spares and the drawings never existed, or walked out the door with someone’s retirement; a supplier vanished and took the documentation with them. The part in your hand is the only record left. Reverse engineering, in the usual sense, is measuring an object and reconstructing it as a 3D model, and it is one way to keep legacy equipment running after its original maker stops supporting it (source 1).

Reverse engineering turns that one surviving part into engineering files. The next time it wears out, you reorder from a print instead of starting the scramble over. If you are starting from an idea or a sketch rather than a physical part, getting a custom part made without CAD is the page for that journey; this one is for the part that already exists.

Obsolete or discontinued part, remade from a sample

The most common version of this job is a part nobody sells any more: a bushing, a shaft, a bracket, a fitting, a punch, a wear plate on a press, a packaging line, a tractor, a lab instrument, or a piece of process equipment whose maker no longer exists or no longer supports the model. The distributor has no stock, the OEM quotes a whole assembly or nothing, and the machine is down or about to be.

A new sample part comes back as new parts that fit, plus the print that makes the next one a reorder. Send a new part, not the worn one. Wear changes the sizes that matter. Wear is the gradual removal or deformation of material at a surface (source 2), so a bushing that has worn no longer shows its intended bore, and a shaft journal that has worn a step no longer shows its size. The sample ships back with the parts, or on its own when the job ends in files only. Where the original designer’s intent is genuinely ambiguous, you get a question rather than a silent guess. You can also ask for the remake with a change, such as a known weak point thicker or a bronze bushing where the original was plastic. A design change is quoted as its own line, as CAD design work.

The same route covers the tooling behind a product: a forming or EDM punch for a die whose drawings are gone, or a fastener nobody stocks, both measured from a new sample part and remade to match. Parts are supplied as replacements by fit and dimensions. No OEM logos, part numbers or markings are copied. Cast parts are not quoted, either as a casting or as a machined replacement for a part that was originally cast. Parts machined from cast bronze bar, such as C93200 and C95400 bushings, sleeves and wear rings, are normal work.

How can I reverse engineer an obsolete part with no original drawings?

With no drawings, the route is a new sample part. Start with photos and a description; the part is then measured and drawn up as a STEP model and a dimensioned print, quoted as its own line, and new parts are made to that print and inspected against it. The steps, in order:

1. Assess. Send photos, a description of what the part does, and where it fits, through the quote form. You hear back with what to ship, what new mating parts or photos of the assembly would help, and a quote for the measuring work, within 24-48 hours.

2. Measure. The physical part is measured, so the sizes on the new drawing are measured values, not estimates traced off a photo. Critical fits are cross-checked against new mating parts when you send them.

3. Model and print. A 3D STEP model and a 2D PDF print with dimensions, tolerances, material, and finish callouts, written in the dimensioning and tolerancing notation that ASME Y14.5 standardizes (source 3). Tolerances, material and finish are set with you, not read off the sample. The files are yours outright and usable with any supplier.

4. Get made. Approve the quote for new parts and the remake is sourced from that print like any other job: one piece or a small lot, with a choice of Rush 1-2 weeks, Standard 4-6 weeks or Extended 6-8 weeks. Rush 1-2 weeks applies to machined parts with no secondary operations. Heat treat, grinding, EDM and finishing add time, and the quote gives the real date. Rush is quoted at a premium.

5. Inspect against the measured print. Every part inspected against your print before it ships. Here your print is the drawing that came out of step 3, with the critical fits checked against the sizes measured off your original. It goes out with tracking.

Order a spare while the setup exists

A remade obsolete part ordered as a single piece carries all of its programming and setup alone. Ask for more than one quantity, such as 1, 25 and 100, and the quote shows each. If the original failed once it can fail again, and a spare on the shelf is there when it does. Reorders at the same revision: send the last quote or PO number and it’s requoted. One-off CNC machining covers the single-piece order in more detail.

What measuring can and cannot tell you

Measuring a part reveals its geometry. It does not reveal its heat treat, its exact alloy, or its surface treatment, and a print that silently claims to know those is fiction. So material is handled honestly: what the part looks like, weighs, and does in service narrows the family (a bronze bushing, a hardened steel pin, an aluminum bracket), and the drawing states the grade that was specified with you, not one that was guessed. A Rockwell hardness test of the kind ASTM E18 covers (source 5) gives the hardness of a steel part, and a grade-verification method of the kind ASTM E1476 describes (source 6) can help confirm the alloy. Either can be arranged and quoted with the job; neither is routine.

One measured part also shows one set of sizes, not the tolerance band the original was drawn to; tolerances are assigned to a part as boundaries for acceptable build (source 4), so on the new print they are set with you. The practical read: for most obsolete parts the intended function, not the original alloy, is what you are buying. Where the alloy is the point (a magnet-sensitive part, a food-contact or corrosion-critical surface), say so up front and it gets pinned down before anything is made.

What you get back

A 3D model (STEP) and a 2D PDF print with dimensions, tolerances, and material and finish callouts. STEP and PDF as standard. If your workflow needs a native SolidWorks file, a DXF of a flat part or the revision history, say so and the quote confirms it. The files are yours outright (usable with any supplier), and new parts from the same print are quoted from it. Quotes come back in 24-48 hours, and one piece is a normal order. Replacement parts for lines that cannot stop are the everyday case on industrial equipment.

Sources

All accessed 4 October 2026. Where a figure here differs from your print, the print governs.

The standards are cited for what a test or a drawing convention covers, not as a claim that any particular test is run on every job; tests beyond measurement are arranged and quoted per job.

1. Wikipedia, "Reverse engineering": en.wikipedia.org/wiki/Reverse_engineering (the process involves measuring an object and then reconstructing it as a 3D model; reverse engineering is one way to support legacy devices no longer supported by their original equipment manufacturer).

2. Wikipedia, "Wear": en.wikipedia.org/wiki/Wear (wear is the damaging, gradual removal or deformation of material at solid surfaces).

3. ASME Y14.5-2018 (R2024), "Dimensioning and Tolerancing": asme.org/codes-standards/find-codes-standards/y14-5-dimensioning-tolerancing (establishes symbols, rules, definitions, requirements, defaults and recommended practices for stating and interpreting dimensioning and tolerancing on engineering drawings).

4. Wikipedia, "Engineering tolerance": en.wikipedia.org/wiki/Engineering_tolerance (tolerances are assigned to parts for manufacturing purposes, as boundaries for acceptable build; measurement error and statistical uncertainty are present in all measurements).

5. ASTM E18-22, "Standard Test Methods for Rockwell Hardness of Metallic Materials": store.astm.org/e0018-22.html (determination of Rockwell hardness by the indentation hardness principle).

6. ASTM E1476-04 (2022), "Standard Guide for Metals Identification, Grade Verification, and Sorting": store.astm.org/e1476-04r22.html (nondestructive methods for identifying and sorting metals and for grade verification).