The Handoff Is Where Projects Break

You hire an engineering firm to design the product and a factory to build it. Both are competent, both deliver what their contract says, and the product still ships four months late with a 12 percent scrap rate. Almost every time, the cause is the same: a set of tasks that neither party believed was theirs.

Development firms and manufacturers have different business models, different margins, and different incentives. Understanding those differences is what lets you write two contracts that meet cleanly in the middle instead of leaving a gap you pay to fill later.

What the Development Firm Owns

A product development firm is selling engineering hours and a design that works. Its deliverables are documents and validated designs, not units.

  • Requirements and architecture. Turning a concept into a written specification with measurable targets, then deciding how the system splits into mechanics, electronics, firmware, and app.
  • Detailed design. CAD models, drawings with GD and T, schematics, PCB layout, firmware, and the analysis behind them.
  • Prototypes and design verification. Building units and proving the design meets the spec: drop tests, thermal runs, battery life, EMC pre-scans.
  • Design for manufacturing. Adjusting the design so it can be built repeatably at the target volume, which is the whole point of design for manufacturing work.
  • The release package. A complete, revision-controlled manufacturing data package: 3D and 2D files, a costed bill of materials with approved manufacturer part numbers, assembly instructions, test specs, and packaging drawings.

What the firm does not own: yield, unit cost at volume, component purchasing, line capacity, or the factory's labor. If your contract asks a design firm to guarantee a landed cost per unit, you are asking it to underwrite risks it cannot control.

What the Manufacturer Owns

A contract manufacturer is selling capacity and units at a per-piece margin, usually thin. It optimizes for a stable, repeatable process and hates change.

  • Process engineering. Fixtures, jigs, line layout, cycle times, and the assembly sequence that turns your instructions into a repeatable operation.
  • Tooling execution. Building molds and dies to your data, running trials, and correcting the steel.
  • Purchasing and supply chain. Sourcing to your approved BOM, managing lead times, flagging obsolescence.
  • Quality on the line. Incoming inspection, in-process checks, functional test, outgoing sampling, and corrective action when something drifts.
  • Delivery. Hitting quantities and dates against the purchase order.

What the manufacturer does not own: whether the design is a good product, whether it will pass certification, or whether the requirements were right. A factory will build exactly what you released, including the mistakes. That distinction is the core of what a contract manufacturer relationship is and is not.

The Six Gaps That Fall Between the Chairs

These are the items neither contract usually names, and they cause most of the pain.

Tooling design review. Your engineer designed the part; the toolmaker designs the mold. Gate location, ejector placement, and parting line all change the part, and nobody has explicitly signed up to review the mold drawing before steel is cut. Assign it, in writing, to the development firm with a defined number of review hours.

First article and trial sample judgment. When trial parts arrive, somebody has to decide whether a 0.3 mm warp is acceptable. The factory says it is within its capability; you have no basis to argue. Put the development firm on the hook for reviewing the first article inspection report against the drawing.

Test fixtures and end-of-line test. The design firm knows what needs testing; the factory knows how to run a line. Neither budgets for building the fixture. This routinely surfaces six weeks before production and costs $8,000 to $40,000 unplanned.

Certification. The factory will not own FCC, UL, or CE submissions, and most design firms scope only pre-compliance testing. Somebody has to book the lab, own the failures, and pay for the redesign loop.

Component substitutions. The factory finds a cheaper capacitor or an equivalent motor. Who approves it? Without a named engineering approver and a written change process, substitutions happen silently and show up as field failures.

Design changes after release. Every change during ramp affects tooling, inventory, and documentation at once. Run them through a real engineering change order process with both parties on the distribution list, or you will end up with three versions of the truth.

Different Incentives, Predictable Behavior

The development firm bills hours or a fixed fee and is finished when the design is released. Its incentive is to close scope cleanly. The manufacturer earns on volume over years and wants the design frozen and the line stable. Its incentive is to accept the release and quote changes as extras.

Both are rational. The consequence is that after release, nobody has a commercial reason to solve a problem that spans both domains. The fix is contractual: keep a defined block of production-support hours on the development contract, tied to milestones, so the engineers who designed the product are still funded when T1 parts come out of the tool.

Who to Hire First

Hire the development firm first in almost every case, then bring the factory in during detailed design rather than after release. A manufacturer consulted at 70 percent design maturity will tell you which processes it is good at, what its real MOQ is, and which tolerances it can hold, and that feedback is worth more than any DFM checklist. Bring it in after release and its only options are to quote high or to change your design.

The exception is a simple product built on a well-understood process, where an experienced factory's in-house engineering is genuinely enough. Even then, get an independent set of eyes on the drawings; the questions in how to choose a product design firm apply equally to evaluating a factory's engineering department. And be clear about ownership up front, because the answers in who owns the IP in product development get much harder to negotiate once the tool exists.

One Party Accountable Across the Seam

Projects House works both sides of this line: we design the product, release a manufacturing data package a factory can build from, and stay engaged through tooling review, first articles, and ramp so the gaps above have an owner. Tell us where your project sits through our contact form and we will map out who needs to be responsible for what.