The 7 Deadly Sins of Mechanical Design

Have you got your tablet of stone and hammer and chisel at the ready?

Ok, so these are the 7 deadly sins, not the 10 commandments, but you get the idea. You don’t want to make these mistakes in your career if you can possibly avoid them.

In this article, we’ve outlined some of the worst pitfalls when it comes to mechanical design, and more importantly, what you can do to avoid them.

1. Rushing projects

More haste, less speed. In other words, if you’ve left things to the last minute or you have taken on too much just to impress your superiors and can’t cope with the workload, it’s a recipe for design disaster.

Mechanical design is a complex process. You need plenty of time to think, plan, reflect, analyse and create. If you’re pressed for time then you’ll probably start cutting corners to get it finished quickly and make glaring errors that won’t get picked up soon enough, as you don’t have time to go back over it to check.

To avoid this, make sure you have a well-organised work schedule, don’t take on too much and plan the process of each design carefully before starting.

2. Poor attention to detail

This is a very broad mistake, but worth mentioning in its own right as it’s so important to develop the right mindset as a mechanical engineer. The devil is in the detail. You need to be able to focus on the design for long periods, and also get into the habit of coming back fresh to your design after a break and checking it over with a fine toothcomb.

Ok, in all likelihood there will be more than one pair of eyes checking over your design, including an official check by a senior engineer. But if you want to reach the higher ranks of engineering you need to be able to spot the mistakes and lack of detail in your own work and correct it. We can boil this point down to one thing – be meticulous.

3. Getting the dimensions wrong

Even some of the best engineering minds in the world get it wrong sometimes. Just look at the mistakes NASA have made over the years. One of their biggest mistakes was the loss of a Mars orbiter

worth $125 million in 1999. The error came about when engineers from the contractor Lockheed Martin used imperial measurements, while NASA engineers used metric. The conversions were incorrect which wasn’t picked up by either team, thus causing the vessel to orbit 25km closer to the planet that it was safe to do so, dipping into the atmosphere causing the engines to overheat.

The moral of the story? Check your dimensions and conversions. In fact, don’t just check them, double or triple check them, then get someone else to check them. Especially when there’s $125 million on the line!

4. Falling behind the curve

Don’t get left behind. Not staying up-to-date with industry developments is a big mistake for mechanical design engineers. In this technological age things change fast, so make sure your knowledge is relevant by subscribing to industry journals, publications, and making sure you’re a member of the Institute of mechanical engineers.

5. Not thinking about the assembly process

It’s easy to get wrapped up in your design and forget about the practicality of actually putting it together. Make sure you are thinking about misassembly during the design. Try to foolproof your design, in other words, you want to make sure that, if possible, the pieces can only go together in one way to avoid the chance of misassembly. Also known as ‘poka yoke’.

6. Not applying common sense checks

Make sure the results of your calculations make sense. If you determine the velocity of a crankshaft to be 1000 m/s, ask yourself if this is realistic! Again, this comes back to developing the right mindset. Always question everything you do. Question it, check it, and check it again is a good motto to live by.

7. No consideration of design presentation

At the end of the day, your design is going to be seen by lots of people – engineering managers, finance managers, CEOs, manufacturers, etc. It needs to be clear, not just to you, but to everyone else. That’s why we have design standards, so try not to deviate from them. It may not be a big deal to you if the dimensions are incorrectly labelled on the CAD drawings, but this could irk or confuse others. Also, make sure you are constantly practising and developing your interpersonal skills. There’s a good chance you’ll have to present your design in person, therefore make sure you figure out how you’re going to communicate the concepts and practicalities of the design beforehand.