Scope creep on CNC jobs can erode your margins by 20–40% before you realize what happened. A vague revision policy is the fastest way to lose control of a project's timeline and cost. Setting clear boundaries upfront keeps customers happy, protects your bottom line, and builds predictable operations.
Why CNC Jobs Are Vulnerable to Scope Creep
CNC machining projects often start with rough sketches or verbal requirements. A customer mentions "a few tweaks" to tolerances, adds a secondary operation, or requests material substitutions mid-run. Each change cascades: new tool paths, setup time, operator adjustments, inspection cycles. Before you've billed half the project, you've absorbed hours in uncompensated work.
The problem intensifies with repeat customers or relationship-based sales. It's harder to push back on a long-time client than a one-time order, yet that's exactly when you need boundaries most.
Build Scope Into Your Quote
Your revision policy starts before the contract is signed.
Define the baseline clearly. Your quote should specify:
- Exact dimensions, tolerances, and surface finishes (reference the CAD file by version and date)
- Number of pieces and delivery timeline
- Material grade and supplier specs
- Which operations are included (turning, milling, drilling, deburring) and which cost extra
- Inspection checkpoints and acceptance criteria
Vague language like "finish to print" or "as needed" invites arguments later. Instead, write "DIN 13 surface finish" or "±0.005" on 8mm holes" so there's no ambiguity.
Include a revision clause in pricing. Quote customers for a specific number of design revisions—typically one or two—before tooling or full production. Most jobs don't need more. If they do, state the cost: "$150 per revision hour" or "revisions billed at $85/hour after two rounds."
Create a Written Revision Policy
Put your policy in writing and attach it to every quote and purchase order.
Sample policy structure:
- Included revisions: Up to two rounds of CAD review and tool path adjustments before first article production
- Charged revisions: Any changes after the second round, or changes requested after production starts
- Revision costs: Billed at your loaded hourly rate (typically $75–$150/hour for CNC work, depending on region and complexity)
- Urgent revisions: Rush changes incur a 25% premium and may delay delivery
- Scope freeze: No design changes accepted within 48 hours of scheduled run
This protects you without sounding hostile. Customers expect to pay for changes; they just want to know the rules upfront.
Track Changes and Time
Use a simple system to log every revision request.
- Email confirmation: When a customer requests a change, reply with a summary: "Changing 10mm bore to 12mm, adding chamfer, reviewing new tool path—estimated 2 hours." Get their approval before proceeding.
- Job notes: Record revision time separately from billable production time so you can spot patterns (e.g., which customers consistently revise, which products tend to need rework).
- Change order form: For significant revisions, issue a signed change order that updates the delivery date and price. This creates accountability.
Many CNC shops use job tracking software like Shopify, Xplor, or even a detailed Excel log to manage this. The key is consistency—every revision gets logged the same way.
Set Delivery Boundaries
Time creep is scope creep too.
- Quote delivery as a firm date. If a customer wants revisions in week three of a four-week project, they slip to the next run. Build buffer into your schedule so you're not caught off-guard.
- Revision freeze before delivery: Announce that no design changes are accepted in the final week before shipment. This prevents last-minute panic requests that blow your timeline.
- Expedited delivery costs extra. If a customer wants a revision completed and parts shipped within days instead of weeks, charge 40–60% more for the rush.
Educate Your Customers
Frame your revision policy as a service, not a barrier.
When quoting, explain: "We include two rounds of CAD review so you can verify tolerances and finishes before we run your parts. That usually catches issues early and saves rework." Customers understand that quality requires control, and they appreciate clarity.
When listing your services on Mercoly or other platforms, mention your revision policy in the service description—it signals to serious buyers that you run a professional, organized operation and helps you attract customers who value transparency.
Frequently Asked Questions
Q: What counts as a revision vs. a new order? A: A revision modifies the existing design or specifications (different hole size, tolerance change, added feature). A new order is a different part or a fundamentally different version. Revisions are covered by your policy; new orders are separate quotes.
Q: Should I charge for revisions that are my mistake? A: No. If you misread the print or made a tool path error, fix it free. If the customer changes their mind or the spec was ambiguous in the original quote, it's a chargeable revision. Document the difference clearly.
Q: How do I handle a customer who ignores the revision policy? A: Politely remind them in writing (email) of the terms they agreed to, reference the quote number, and issue an invoice for revision time. Most customers pay once they see the bill; a few may push back, but you've established a boundary.
Ready to attract more CNC machining customers who respect your processes? List your capabilities and revision policies on Mercoly to reach buyers actively looking for precision machining with professional operations.