A buyer may send Rev D of a drawing after estimating has started. The title block changed, a shaft runout tightened from 0.08 mm to 0.04 mm, a note now calls for a C5-M coating system and the attached BOM still points to Rev C. Each change reaches a different owner. The tolerance affects machining and inspection. The coating affects supplier scope and lead time. The BOM conflict needs a customer answer.
Visual comparison can show where the page changed. The commercial job starts after that: identify the requirement, decide whether it matters, find the work that used the old revision and update the offer before release.
Identify the baseline before you compare files
Record the customer document number, revision, issue date, approval status and source transmittal. Confirm that both files describe the same part, assembly, site or project. “Final.pdf” and “final-new.pdf” are filenames, not configuration identifiers.
Then find the working baseline. Which drawing, model, specification and BOM did application engineering, estimating and suppliers use? A current customer file can arrive after the team has already built cost and schedule against the previous issue. Revision control needs both facts: the customer’s current set and the set behind the active quote.
ASME Y14.35 defines methods for identifying and recording revisions to engineering product definition data and related documents. Apply that discipline as soon as the RFQ enters the business, before files spread into email folders and supplier packages.
| Baseline field | Question to answer |
|---|---|
| Document identity | What drawing, model, specification, data sheet or list is this? |
| Revision | Which issue, date and approval state does the customer recognize? |
| Source | Which email, portal transmittal or customer record supplied it? |
| Relationship | Does it replace, supplement or conflict with an earlier document? |
| Use in the bid | Which configuration, estimate, supplier RFQ or proposal used this revision? |
| Authority | Who can decide precedence when two current sources disagree? |
Set document precedence and check every reference
Do not let the parser decide which file wins. The contract documents may define an order of precedence. The customer may issue a clarification that overrides one note. Your own proposal may state a deviation that the buyer later accepts. Record the rule and its source, then route unresolved conflicts to the customer.
Check referenced documents as part of the revision set. A drawing can stay at Rev C while a referenced paint specification moves from Rev 4 to Rev 5. The page comparison will show no change, yet the required preparation, dry-film thickness, inspection and cure schedule may have changed. Build a reference list from drawing notes, specification sections, BOM entries and customer standards.
| Reference check | Failure it catches |
|---|---|
| Referenced document is present | A requirement points to a standard the team never received |
| Referenced revision is known | The supplier uses a newer or older rule than the customer intended |
| Part and assembly revisions agree | A component drawing changed while the assembly or BOM stayed old |
| Customer clarification is attached | An email decision never reaches the technical package |
| Proposal deviation is mapped | The offer claims compliance with a requirement it changed |
Compare the requirements
A moved view or reformatted title block can create thousands of changed pixels without changing the product. A single tolerance, material note or test requirement can alter the manufacturing route with little visual difference. Extract the requirement changes first, then show the page, zone or model feature as evidence.
Compare the categories that can change scope or acceptance. The exact list depends on the product, but an industrial OEM usually needs to inspect geometry and interfaces, dimensions and tolerances, materials, finishes, special processes, BOM items, approved makers, performance, testing, documentation, marking, packaging and referenced standards.
| Requirement group | Examples of a material change | Likely quote effect |
|---|---|---|
| Geometry and interfaces | Footprint, nozzle orientation, mounting holes or cable entry | Configuration, layout, fabrication and site fit |
| Dimensions and tolerances | Datum, fit, runout, flatness or surface finish | Process route, tooling, inspection, scrap risk and lead time |
| Material and process | Grade, coating, heat treatment, weld procedure or cleanliness | Supplier, cost, qualification and schedule |
| BOM and approved source | Quantity, manufacturer, part number or make/buy boundary | Purchased scope, availability and price break |
| Performance and test | Duty point, load, efficiency, test method or witness point | Product selection, engineering, equipment and guarantee |
| Deliverables and logistics | Certificate, manual, packing, marking or delivery condition | Labor, documentation, freight and customer acceptance |
Compare the model, drawing and BOM as one product definition
A 3D model may carry the geometry, dimensions, tolerances, datums, surface requirements and product structure that define the part. ASME Y14.41 covers the preparation and revision of digital product definition data sets. If the customer uses a model as an authority, its structured data forms part of the product requirements.
For STEP data, compare geometry, product and manufacturing information, validation properties and file integrity. NIST’s STEP File Analyzer and Viewer reports entity and attribute data, semantic and graphical PMI, validation properties and basic format errors. That distinction matters. A semantic tolerance can support downstream machining or inspection; a graphical annotation may only look correct on screen.
Reconcile the model, drawing and BOM before the team accepts the new baseline. A model can add two fasteners while the BOM keeps the old quantity. A drawing can tighten a tolerance that the model still expresses at the earlier value. When the sources disagree, raise the conflict, cite both sources and send the decision to the engineer who owns it.
Classify each delta before you route it
Separate editorial changes from changes that affect the offer. Also record requirements that disappeared. A removed inspection note, certificate or customer-supplied item can leave obsolete cost in the estimate or create a gap in acceptance if nobody notices it.
Record detection confidence separately from business effect. Software may be highly confident that a note changed and still be unable to judge whether the change alters the process. A qualified owner makes that decision with the old requirement, new requirement and source locations in front of them.
| Delta class | What it covers | Required treatment |
|---|---|---|
| Editorial | Layout, spelling or presentation with no change in meaning | Record and dismiss after review |
| Technical | Form, fit, function, material, process, performance or acceptance | Assess product, cost, schedule and compliance |
| Commercial | Quantity, delivery, documents, warranty or another obligation | Reopen the estimate, plan or commercial approval |
| Conflict | Two current sources impose different requirements | Open a technical clarification and name the deciding authority |
| Removed | A requirement from the prior baseline no longer appears | Remove obsolete scope only after dependent work is checked |
| Uncertain | The comparison found a difference whose meaning is unclear | Send it to a qualified reviewer and leave affected work open |
Trace each material change into the quote
A reviewed delta becomes useful when the system can find the work that relied on the old requirement. The NASA Systems Engineering Handbook describes evaluating a requirement change across cost, schedule, architecture, design, interfaces and related requirements. An industrial bid needs the same discipline at a smaller scale.
Link each accepted requirement to the configuration, BOM line, drawing, supplier package, cost line, routing step, inspection, schedule activity, compliance response and proposal statement it affects. Give each responsible person a complete review list. They decide the effect on their work.
| Affected work | Question the revision creates | Accountable owner |
|---|---|---|
| Configuration and engineering | Does the selected product or design still meet the customer requirement? | Application or product engineering |
| Supplier RFQs | Did a supplier price the current material, finish, test and quantity? | Sourcing |
| Cost and margin | Which material, labor, outside-process or risk allowances changed? | Estimating and commercial lead |
| Capacity and delivery | Did the route, bought-out lead time or approval cycle move the promised date? | Planning or project operations |
| Quality and compliance | Do the inspection plan, certificate set and compliance statements still apply? | Quality engineering |
| Proposal | Which scope, price, schedule, exception and attachment must change? | Proposal owner |
Process a late revision without losing the bid baseline
Freeze the working quote revision before applying the new customer files. Preserve the old source set, estimate and proposal. Compare the new issue with that baseline, then reopen only the work tied to material changes. This keeps unaffected work moving and gives the approver a clean before-and-after record.
For each material delta, choose a commercial response: absorb it, reprice it, move the delivery date, offer it as an option, state a deviation or ask the customer to extend the bid deadline. Record who approved the response and which evidence they reviewed. A changed drawing does not become part of the offer until the affected technical and commercial decisions are complete.
ISO 10007 gives configuration-management guidance across a product’s life cycle. For quoting, the practical rule is simple: every submitted offer must point to one known customer baseline, and every later offer must preserve the baseline it replaced.
Worked example: Rev D changes an industrial fan package
An OEM prices a fan package against assembly drawing F-220 Rev C, specification S-19 Rev B and paint specification P-04 Rev 4. The customer then sends F-220 Rev D. The discharge orientation moves 180 degrees, the shaft runout tightens from 0.08 mm to 0.04 mm and a note calls for P-04 Rev 5. The attached BOM still names F-220 Rev C.
Application engineering checks the new orientation against the customer’s duct layout. Manufacturing engineering and quality review the tighter runout, add a grinding operation and revise the inspection method. Sourcing sends the coating supplier P-04 Rev 5 and requests a new price and lead time. The stale BOM becomes a customer clarification because the team cannot prove whether the BOM or drawing governs the supplied arrangement.
The revised estimate adds machining, inspection and coating cost. Planning adds one week for the outside process. The commercial lead updates the price and delivery date. Proposal Rev 2 identifies F-220 Rev D, S-19 Rev B and P-04 Rev 5 as its source set and states the open BOM clarification. The team can show exactly why the price and date changed.
Release the quote after every material delta has a disposition
A green check means that the responsible owner accepted the effect, updated the dependent work and recorded the response. Opening the file does not count. Before release, confirm that every supplier package uses the current source set and that the proposal names the baseline behind its price and delivery.
Measure the workflow from the arrival of a new revision to an approved quote response. Counting detected changes alone rewards noisy comparison. The better measures expose whether the business found the change, reached the right owner and updated the offer before submission.
| Measure | What it reveals |
|---|---|
| Revision detection time | How long the new customer issue sat before the bid team recognized it |
| Material deltas with owners | Whether each cost, schedule or compliance change has a responsible reviewer |
| Affected tasks updated | Whether the change reached every estimate, supplier, plan and proposal item it touched |
| Supplier packages current | Whether outside prices and lead times use the same baseline as the offer |
| Stale-requirement defects | How often an old or conflicting requirement reaches review, submission or order handover |
| Change response time | How quickly the team can submit a controlled price, date, option, deviation or question |
How Bourne handles revision control
Bourne inventories the customer source set, identifies each document and revision, and compares an incoming issue with the baseline behind the active quote. It groups related changes into requirements, shows the old and new source locations and routes each material delta to the person who owns the decision.
After approval, Bourne reopens the affected configuration, costing, supplier, schedule and proposal work. It preserves the earlier files and decisions, and it records the exact source set behind each offer revision. Engineers decide technical meaning. Commercial owners decide the response. Bourne makes sure those decisions reach the quote.
Buğra Gündüz
Buğra Gündüz is the co-founder and CEO of Bourne and co-founder of HockeyStack. He built HockeyStack into an eight-figure AI business. At Bourne, he works with entrepreneurs and established companies to create AI products and services.