Working with The Mechanical Engineering Team

This week I delivered five electrical prototypes to a world renowned industrial designer. Here's a few lessons I learned:

Mechanical guys like datasheets but they love datasheets plus samples. Give them samples of everything, particularly switches, connectors, displays, light pipes, etc. If you need a 3D model (aka STEP file) of one of the components for the PCBA layout, just ask them.

Many electromechanical products (switches, battery contacts, connectors, etc.) have more mechanical requirements than electrical requirements. So for these I will give some high level guidance to the ME but let her choose the final components.

Get the prototype enclosure and any other mechanical parts as soon as you can. I have yet to see a product where the first mechanical and electrical prototypes fit together perfectly. Have the ME there when you first assemble them together to discuss any problems right away.

Good things to have on-hand for modifications to the enclosures: Dremel, hot-glue gun, and strong double-sided tape. Also if you’re really fancy, get carbon paper or dental articulating paper to determine where things are rubbing.

For tight designs, some of the higher-end PCB layout programs (Altium, for example) will produce a 3D model of the PCB from the layout. This is very useful, and then creates a 3D space contract between electrical and mechanical. We do this on every design, as it helps to visualize the board.

When determining how much space you'll need, don't forget to take into account space for wiring loops, turn radius, heat, etc. Placing a hot resistor right up against the plastic enclosure wall may result in failing UL due to elevated chassis temperature.

For a prototype, try to get as much board space as you can. There will always be surprises.

At some point both you (the electrical engineer) and the mechanical engineer will screw up something, so don't be too hard on each other. Be nice when they screw up and chances are they'll be nice to you when you screw up.

Spare, Spares, Spares: if you're working on a product for a demo, get extra enclosures and make extras of everything. On one of my prototypes a stupid little $0.20 battery holder prevented the a system of 3 devices from working. Of course it worked fine in the lab and failed when I got over to the client. Unfortunately I didn't have any spares so I had to troubleshoot it and fix it there on the spot. Doh!