When a replacement part has no usable drawing, the physical sample is often the starting point—not the complete specification. Measurements alone cannot always reveal its original dimensions, material, surface treatment, or intended fit. The information needed to reverse engineer a part includes the sample, how it works, and records that help distinguish critical features from incidental ones.
This checklist helps engineers and purchasing teams organize an inquiry and identify decisions needed before manufacturing. It is not a statement that Anco Precision provides reverse engineering, material identification, engineering approval, or design validation. Confirm the scope of any requested services with the supplier; a machining quote and the engineering work needed to define a part are not necessarily the same service.
Start with the physical sample
Provide the most complete and representative sample available. If practical, include both a known good part and worn or damaged examples. Differences may help identify wear, deformation, or previous repairs. Label each sample and explain its history rather than assuming its condition is obvious.
Clean the part enough to expose its features, but avoid removing coatings, polishing wear surfaces, or modifying damaged areas before discussing the sample. Those details can be useful clues. Identify removable components, such as inserts or fasteners, and say whether they are included in the requested replacement.
A sample shows the part's current condition, not necessarily its original design. A bore can become larger through wear, a shaft can become smaller, and impact or heat can distort features. If you want the part reproduced as received, say so. If you want to restore its original function, explain the known problem and identify the features affected.
Provide mating components and assembly context
Mating components can reveal which surfaces locate the part, which holes accept fasteners, and where clearance or a close fit matters. If practical, provide the mating pieces or an assembly drawing. If they cannot be sent, share relevant dimensions, photographs, and any fit requirements you know. Confirm shipping arrangements before sending physical parts.
Describe how the part is installed, which direction loads act, whether it rotates or slides, and what it contacts during operation. Note features that must align with existing equipment. For example, mounting-hole spacing may be more important to installation than the appearance of a noncontacting exterior surface.
Explain the intended function
Describe what the part does and what happens when it fails. A locating pin, sealing surface, and simple spacer can require different attention even if their shapes are similar. Mention operating conditions such as heat, moisture, chemicals, impact, or repeated loading. If the part must interchange with existing components, make that requirement clear.
Share drawings, CAD files, and known dimensions
Send any available drawings, sketches, CAD files, and documentation, even if incomplete. A STEP file can communicate three-dimensional geometry; a drawing can define dimensions, tolerances, notes, and other requirements that may not appear in the model. Identify the latest approved revision and flag information you suspect is outdated.
Identify which document controls if the drawing, CAD model, and physical sample disagree. Resolve conflicts before machining rather than assuming design intent can be determined from a model or sample alone. The responsible engineering authority should approve the final requirements.
Provide known dimensions and explain how they were obtained. Mark critical diameters, hole locations, overall length, thread details, and mating dimensions where available. If a measurement came from a worn surface or a basic hand tool, identify it as approximate. A sample measurement is not automatically the original nominal dimension or an acceptable manufacturing tolerance.
Identify unknowns instead of guessing
If you do not know a thread type, material grade, or bore size, say so. Photographs with a scale and notes about where the part fits can help frame the question, but they do not replace a defined requirement. Ask which unknowns must be resolved before pricing or manufacturing and who will resolve them.
Specify material, finish, and operating requirements
Material selection affects machining, performance, and cost. Provide the material grade if known, along with any relevant condition or heat-treatment requirement. A label such as “steel” or “aluminum” is a starting point, not necessarily a complete specification. If the material is unknown, share markings or records and describe the operating environment and needed properties.
Do not assume the original material can be identified accurately by appearance. If identification is essential, determine what testing or other evidence is needed, who will arrange it, and who will approve the result. If a substitute is acceptable, state who can approve it and which properties must be preserved.
Identify surfaces that seal, slide, bear against another part, or need a particular appearance. Specify surface finish where it matters, and note any required coating, plating, or other treatment. A visibly smooth surface does not by itself communicate a measurable finish. Clarify whether dimensions apply before or after treatment, particularly on mating features.
Define tolerances around function
A measured feature needs an allowable variation before it becomes a practical manufacturing requirement. Identify the dimensions and geometric relationships that control fit and function, including hole positions, alignment, flatness, and concentric features where relevant. Provide tolerances on the drawing when known and explain the functional reason for especially critical requirements.
Avoid applying the tightest possible tolerance to every feature. Unnecessarily restrictive requirements can increase machining and inspection effort without improving performance. Conversely, an undefined critical fit can result in a part that matches the general shape but does not assemble or operate correctly.
If you are unsure of a tolerance, describe the mating condition and provide the mating component or its specifications. The required fit should be agreed upon rather than inferred from a worn sample. Distinguish dimensions essential to the assembly from those that can vary without affecting function.
Explain wear, damage, and proposed changes
Point out cracks, worn contact areas, bent features, corrosion, and previous modifications. Explain whether a damaged feature should be restored, redesigned, or copied as found. If the original failure is not understood, say so; reproducing the same geometry and material may also reproduce the conditions that led to failure.
Separate confirmed requirements from desired improvements. For example, you might require the same mounting interfaces while asking whether a noncritical feature can change. Any change affecting fit, performance, or safety should be reviewed and approved by the responsible party before manufacture.
Consider prototype and production quantities
Provide the quantity needed now and, if known, expected future demand. A prototype may be intended to check fit, function, or an unproven design, while a production order typically depends on a stable, approved specification and repeatable requirements. The appropriate approach depends on the part and its purpose, not on a fixed numerical definition of a prototype.
For an early part, explain what you plan to test and whether changes are likely after evaluation. For repeat orders, communicate expected release quantities, timing, revision control, and consistency requirements. These details help a supplier assess programming, workholding, material purchasing, and inspection effort.
If a first article or sample needs approval before the rest of an order is made, state that in the RFQ. Explain who will perform the functional test and how acceptance will be communicated. A dimensional check does not necessarily prove that a part will perform in its assembly.
Include inspection requirements and the required date
Identify what must be checked and what documentation you expect with the parts. This might include critical dimensions, a requested inspection report, or acceptance criteria for visual features. Identify customer-specified standards, certifications, and documentation requirements in the RFQ rather than assuming they are included. Confirm whether they can be met before placing the order.
Provide the required completion or delivery date and clarify which one you mean. Include milestones such as design approval or sample testing, and explain if the date is firm. Incomplete specifications, material availability, and unresolved questions can affect scheduling, so share constraints early.
Minimum package for a sample-based inquiry
If the physical sample is all you have, start with the following information rather than guessing at missing specifications:
- Sample condition and history: Describe known wear, damage, repairs, and whether the goal is to copy or restore the part.
- Function and assembly: Explain how it is used, what it mates with, and any known failure or operating conditions. Include photos or mating-part information if available.
- Quantity: State how many parts you need and whether an initial part is for evaluation.
- Critical dimensions or fits: Identify known mounting features, mating dimensions, threads, and fit requirements; label estimates as such.
- Material and finish: Share any known grade, condition, coating, or surface requirement, and mark unknowns.
- Target date: State the desired completion or delivery date and any testing or approval milestones.
A sample alone may not support a firm machining quote. Unresolved material, geometry, tolerance, finish, or inspection requirements may need clarification before pricing. Ask the supplier what information is needed and confirm separately whether any requested engineering work is within its scope. Assign responsibility for defining and approving the final specification and validating the part's function.
Practical RFQ checklist
As the project develops, gather as much of the following as possible for a complete sourcing package:
- Physical sample: Identify condition, known wear, damage, repairs, and whether it represents the intended final part.
- Mating components: Supply mating parts, assembly information, or relevant dimensions and photographs.
- Function: Describe installation, use, operating conditions, failure history, and interchangeability needs.
- Drawings and CAD: Send available drawings, revision information, sketches, and a STEP file or other CAD model. Flag discrepancies and identify the controlling specification.
- Dimensions and tolerances: Identify critical features, fits, threads, and approximate measurements; distinguish requirements from estimates.
- Material and surface finish: Specify grade and condition if known, plus required finishes, treatments, and affected surfaces.
- Quantity: Give the current order quantity and expected future demand, noting whether the part is for evaluation or production.
- Inspection: List critical checks, acceptance criteria, and requested reports or other documentation.
- Schedule: State the required completion or delivery date and approval or testing milestones.
- Special notes: Identify acceptable substitutions, proposed changes, unresolved questions, and the person responsible for approvals.
You do not need every answer to begin an inquiry. Separating known requirements from open questions helps each party establish what must be defined, who will define it, and what can be quoted.
Request a CNC machining quote
For an active project, send Anco Precision your drawing or STEP/CAD file when available, material, quantity, critical requirements, and desired delivery date. If you have only a sample, include the sample-based information above and ask what is needed for a machining quote. Confirm the scope of any additional engineering services separately. Request a CNC machining quote.