Deterministic Design 


Everything happens for a reason, and we merely need to apply the proper resources and focus in order to discover and understand the issues that would otherwise lead to uncertainty. Minimizing uncertainty, and hence risk, makes a design more deterministic. Deterministic design1 can be facilitated through the use of a structured design process. While it might be possible to debate whether design itself is a deterministic or stochastic (shoot-from-the hip) process, it is best to focus creative and analytical forces on real design problems in order to stay on the schedule. 


Engineering design problems are essentially cost and performance trade-offs, and a key element of performance is time to market. It does not matter how good your solution is if you miss the market window. Consequently, engineers with a vibrant passion for success live on the (appropriate) edge. Because the edges move as cost/performance requirements change, engineers and managers must remain nimble, open-minded, and on continual lookout for disruptive technologies2 that can deliver far more performance for far less cost (e.g., integrated circuits verses vacuum tubes). 


The stagnant edge is the realm of the complacent engineer who is asking a competitor to come and take away market share and the business. All too often an engineer gets good at doing something and then fails to realize that new methods have been developed that can provide better performance for less cost. This is akin to riding on the flat bottom of your snowboard while gazing at the sky. You are asking for a face plant or a tree hug! 


The leading edge is the place to be as it means that it is very difficult for a competitor to do better than you unless they spend a lot of resources, and you are likely doing better than all your competitors. The leading edge can only be maintained by constant vigilance and being ready to switch to a different technology curve. This is akin to switching between the toe and heel edge of your snowboard as you weave your way through the woods. 


The bleeding edge3 is the place for paranoid engineers who refuse to change their ways and instead think that with just a little more effort, things will work out; however, soon they run out of resources and fail. Creative solutions may appear to be cleverer than solutions arrived at by analytical means; however, if analysis was not applied, it is likely that the solution rests on the bleeding edge. This is akin to the snowboarder who refuses to turn because the hill is too steep, and instead runs off into the woods. Time after time, it is shown that individuals or teams who can simultaneously harness the power of creative and analytical and computational methods outperform those who use less than all three. Only then can you consistently identify the slope with the finest possible powder and then make first tracks! 


Consider the evolution of the machines on which your parts will likely be produced. Linear actuators are key elements that determine the speed, accuracy and force with which the axes move. Sliding contact lead screws worked great for over a hundred years until they gave way to ball screws which are starting to give way to linear electric motors. Each succeeding technology costs more than the other but provides better performance. However, for the new growth area of small machine tools to make mesoscopic (cm3 sized) parts, large forces and strokes are not needed. DC voice coil actuators have all the advantages of linear electric motors yet do not require expensive commutation circuits; thus they can have lower cost and higher performance. Understanding the physics of the problem and the scaling laws is critical! 


Create a table of the basic physical properties and capabilities of the kit parts, and a spreadsheet to study time, motion, power required to score by each different means. Forecast what might be easy and what would be difficult ways to score, and think of strategies and concepts for ideas that are not easy, yet not too difficult. Then think of strategies and concepts for the more challenging scoring methods!


 1.R. Donaldson, “The Deterministic Approach to Machining Accuracy”, SME Fabrication Technology Symposium, Golden, CO, Nov. 1972 (UCRL preprint 74243).

 2.Clayton M. Christensen, The Innovator’s Dilemma, 1997 Harvard Business School press, Boston, MA. USA

 3.The term bleeding edge was coined by Richard W. Slocum III, a gifted project manager and a key catalyst in the life of his little brother who is eternally grateful for the butt kickings he received that enabled all you are reading to come to be. Thanks Rick for keeping me focused!






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