How do I charge for design help or engineering changes?

Example: moving a pocket away from a thin wall

Assume a customer wants 30 aluminum sensor housings, each 3 × 2 × 1 inches. The customer asks the shop to review a deep pocket near a mounting wall, propose a machining-friendly alternative and update the supplied CAD after the customer's engineer selects it. This is a purchased design-assistance task. Merely choosing a cutter or programming the approved geometry belongs in the manufacturing estimate instead.

Budget 0.75 hour for feature and workholding review, 1.25 hours for one proposed CAD change and 1.00 hour for checking the files and a customer review. Three hours at $135 gives $405. Authorize up to four hours, or $540, with billing for actual recorded time. At an assumed burdened engineering cost of $85 per hour, three hours cost $255 and leave $150 before other unallocated expenses. No rate here is an industry benchmark.

Define what the engineering line purchases

Name the incoming part and revision, the issue to investigate, the output file formats and the number of review cycles. A marked PDF recommendation, an edited STEP model and a native CAD assembly are different deliverables. Do not promise editable source files your shop cannot supply. State whether you will check only manufacturability or also perform calculations, testing or other specifically purchased work.

Separate the customer's functional decisions from the shop's proposed process improvement. Increasing a corner radius may simplify machining, but the customer must confirm mating clearances and product performance. Identify who is authorized to release the revised definition and what written approval you require. Commercial approval to spend engineering hours should not be mistaken for approval of the final geometry.

Quote downstream production changes separately

Suppose the customer accepts the revised pocket after the original machine program was already prepared. Assume an additional 1.5 programming hours at a $120 selling rate and a $90 workholding alteration. That adds $270 of manufacturing change charges beyond the $405 engineering example. If the original program had not been made yet, charging for replacing it would have no basis in this scenario.

Check work in process before promising that a change is cheap. Identify material already cut, parts that can be reworked, parts that cannot be salvaged, new inspection work and outside orders that must be changed. Reprice the remaining production scope at the released revision. Avoid billing the same CAD edit once as engineering assistance and again as a programming change unless those are genuinely separate tasks.

Get the scope approved, then control the hours

Example service line: ‘Manufacturability review and one proposed CAD revision for SH-30 revision A: estimated 3 hours at $135/hour, billed for actual time, not to exceed $540 without written approval. Includes one consolidated review and STEP/PDF deliverables. Customer retains responsibility for functional design approval. Manufacturing price and schedule will be reconfirmed after release.’ Have the responsibility and ownership wording reviewed for the actual agreement; it does not automatically override the customer's terms.

Record time against the engineering authorization and send a progress note before reaching the cap. If the customer adds another component or requests a second concept, estimate that addition before continuing. For the next request, offer the bounded service alongside the production quote so both parties can see what is included and what still requires a decision.

• Handle erroneous customer drawings
• Distinguish an estimate from a paid study
• Account for changed work in process