an argument for more prototypes

If you've ever advocated (i.e. solicited funds) for more prototypes, you know it can be a tough sell; how do you articulate the value of frequent  prototyping during the development process?

I find it useful to consider an illustrative (if simplified) anecdote.

Imagine an engineer, Fred, who needs to develop a mechanism(lets say for automatic opening beer bottles. Fred has one man-month of development before he has to send CAD files out for a functional prototype for use at a trade show. The number of prototypes he is allowed to build during development (i.e. not including the functional prototype at the end) has a direct impact on how the project will go:

If Fred is allowed 0 prototypes, he will spend the first two weeks generating concepts, downselecting to the lowest-risk concept, and implementing in CAD. He will then spend the last two weeks checking and double--checking detail; he has only one shot at this, after all.

If Fred is allowed 1 prototype, he will spend the first two weeks generating concepts, downselecting to a low-risk concept, and implementing in CAD. Upon receiving and evaluating the prototype he will spend the last two weeks tuning the areas that don't work or can still be improved (he does not waste time checking on things that are already proven).

If Fred is allowed 2 prototypes, he will spend the first two weeks generating concepts, downselecting to a low-risk concept, and implementing in CAD. Upon receiving and evaluating the prototype he will spend the next week tuning the areas that don't work or can still be improved (he does not waste time checking on things that are already proven). He then spends most of the last week making final adjustments and then has a prototype made to ensure that the design being sent out for functional prototype will function properly.

If Fred is allowed 3 prototypes, he will spend the first two weeks generating concepts, downselecting to a low-risk concept and an innovative high-risk concept. Upon receiving and evaluating these two prototypes he will reevaluate the risk of each concept and potentially move forward with the innovative design. From here he will spend the next week tuning the areas that don't work or can still be improved (he does not waste time checking on things that are already proven). He then spends most of the last week making final adjustments and then has a prototype made to ensure that the design being sent out for functional prototype will function properly.

 

The outcomes of these four scenarios are drastically different, even though the amount of man-hours put in by Fred is virtually the same:

  • 0 prototypes -  best-case scenario: no one is wowed, worst-case scenario is that it doesn't work and the show is missed
  • 1 prototype -  best-case scenario: no one is wowed, worst-case scenario is that even the simple concept doesn't work as smoothly as it should
  • 2 prototypes - best-case scenario: no one is wowed, worst-case scenario no one is wowed
  • 3 prototypes - best-case scenario: people are wowed, worst-case scenario is no one is wowed
It's a compelling difference,

 

In the (likely) even that you don't have enough time to regale colleagues and Clients with entertaining anecdotes, consider distilling the spirit down into something smaller:

  • Prototypes are the only measure of progress. Everything else (reports, analysis, calculations) are just a proxy for prototypes.
  • The "finished product" is just another prototype; whether it's the 1st, 10th, or 50th prototype is the only variable.
  • Prototypes focus the engineer's attention on high-risk areas
  • During rapid development FEA is best used as a comparative tool, not for absolute results; test prototypes for absolute results.
  • i'm sure I'll come up with more... I'll add them (or yours...comments) as they come.

 

Disclaimer: The above example is simple. Client expectations, risk tolerance, external stakeholders, whether or not prototyping methods are sufficiently representative, budget, and so on need to be considered. The point I'm trying to make is that prototypes are often undervalued and that their true value should be recognized so that decisions that take everything into account can be as well-informed as possible.

 

  • Adam

    I agree!  We've had a 3D printer for a couple of years.  Initially, the idea was that it would save money because the cost of each part was a lot less than ordering through a rapid prototype house.  However, the engineers (myself included) are now making more prototypes because it is so easily accessible and the results are better designs.

  • http://www.pdnotebook.com/ loughnane

    The tough part (if you don't have everyone buying in up front) is determining how much better your designs are than they would have been, and how much of that improvement is directly attributable to the improved process allowed by prototyping.

    This concept have continuously prototyping is old hat in software circles (search 'scrum', 'agile', and 'rapid deployment'), but because we deal in physical parts our costs are higher, which changes the value proposition.

    I'm glad you've seen the light; now spread the word.