How do I stop design knowledge walking out with one engineer?

Never let a live model rest on one head, and write down the thinking behind each design the day it goes to the shop. Two habits carry it. One is a second engineer on every model. The other is a brief decision log at each release. Everything below props up those two.

Owners raise this question often enough that it appears in the FAQs of our machinery hub. Below are the follow-ups that tend to come straight after.

• Why a bracket carries a slotted hole, or why a cam has that particular dwell.
• Sizing spreadsheets for ballscrews, bearings, motors and pneumatic cylinders.
• Vendor habits: which gearbox make runs warm, which bearing brand survives a dusty cement plant.
• Tweaks a customer asked for in a meeting that never reached the revision block.
• Cures found during the trial or on site that only the designer heard about.
• How the parametric model is built: skeleton sketches, mates and configuration tables.
• Half-finished work on a laptop or a pen drive.

1. 1

   Build a model register

   One row per live model. Beside it, write every engineer who could modify it without ringing a colleague. Rows with one name are your exposure.

2. 2

   Choose the three riskiest rows

   Best sellers, models that change with every order, and models with open complaints. Begin there rather than chasing full coverage.

3. 3

   Pair each with a second engineer

   Book a joint walk-through of each model. The newcomer to the model asks; the owner of it explains. From now on, both sign every release.

4. 4

   Pull files off laptops

   Models, sizing spreadsheets and vendor datasheets move to shared storage, named by model and revision. Unreleased work moves too.

5. 5

   Open a decision log at the next release

   Half a page that lists the features a fresh engineer would query and why each exists. It ships with the drawing set.

6. 6

   Count it in appraisals

   Second-engineer cover and decision logs count alongside drawings issued in each designer's appraisal.

Pushback is usually fear in disguise. Sole understanding of a model feels like job security, and sharing feels like giving it away. Tell him plainly you want to spare him every shop query and midnight call from site, not to replace him. Let him pick his own second engineer. Credit him in reviews for building cover. Should he refuse even then, handle it as a performance issue in the normal way.

Treat the notice period as a project, starting the day the letter arrives. Schedule each model in turn, with the successor running the walk-through and recording it on video. Audit every folder he holds and move it to shared storage. Take the successor along to meet the customers and vendors he handles. Hold the exit conversation early, so its answers can still change the plan. Close system access on his final day.

Designer leaving, final working day and successor named.
Models owned, ranked by risk.
Walk-through date for each model, and who records it.
Open work and unreleased drawings, each with a target date.
Folders to move from personal storage, ticked when done.
Customers and vendors to meet, with dates booked.
Questions still open after each walk-through.
System access to close on the final day.

Then the second holder may not be a designer at all. A senior fitter who builds the model can review each release and carry half the reasoning. A junior draughtsman can sit in on every change. Some small builders pay an outside engineer to review major releases. Any of these is better than one head holding everything.

Less than most engineers fear. Record what is not obvious, and skip the rest. One test settles it: could a capable engineer change this model without ringing the original designer? If so, the record is enough. If not, the gap is usually a reason, a calculation or a cure found at trial.

A decision log entry is one or two lines. Three samples from a hypothetical bottle capper show the level of detail:

• Slotted hole on the motor bracket: lets the fitter tension the timing belt. Do not replace it with a round hole.
• Longer dwell on the gripper cam: gives the jaws time to close on tall bottles. Found at trial on the second machine.
• Guard hinge on the left side: the customer's operators stand left of the infeed conveyor.
• Bearing upgraded on the capping head: the standard size ran hot at full speed. Vendor datasheet saved with the model.

None of those lines takes a minute to write at release. Each one would take a successor days to rediscover.

The full pattern, with its costs and a stepwise fix, is in the pattern write-up on design knowledge. The broader leaving routine sits in the offboarding and handover checklist, and succession planning names cover for each key engineer before anyone resigns.