As any hardware developer worth their salt knows, getting part dimensions accurate is key for success in manufacturing and ensuring that assemblies fit together in the real world as intended. Among other common problems that can occur and cause a domino effect disaster down the line include mismatched fastener hole placements and loose or overhanging parts.

While much of this work is contingent on manufacturing processes and is best left to the mechanical engineers out there, conducting a tolerance analysis doesn’t have to be rocket science – particularly while a piece of kit is still in the rapid prototyping stage. Of course, if you’re already in the prototyping stage, nothing beats getting dirty with some sandpaper or Bondo and a digital caliper to make some fine-tuned adjustments – but what if you want exact results from the get-go?

“Tolerance analysis isn’t as daunting as it may have seemed at first,” explains mechanical engineer Sean Thomas. “Furthermore, excel calculators make all of this work much easier and more efficient and as you become more familiar with this analysis and the machine capabilities, the dimensional limits can be pushed with less risk and uncertainty.”


Aiming to make this process easier to understand, Thomas recently shared his own excel Tolerance Calculator along with a How to Conduct a Tolerance Analysis for 3D Printed Parts guide over at Fictiv – a young San Francisco startup that promises to deliver 3D printed parts within 24 hours.

Specifically, Thomas focuses on two distinct processes: how to conduct a positional tolerance analysis and how to conduct a linear tolerance analysis for 3D printing applications based on the ±.005” specification for an FDM 3D printer. Along the way, he also shares some tips and tricks for getting from A to B with the most streamlined process.

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Says Thomas:

“(These) methods will ensure the parts fit together the first time, every time, with no modification.”

Download the free calculator and bookmark the guide over at Fictiv.


Simon is a Brooklyn-based industrial designer and Managing Editor of EVD Media. When he finds the time to design, his focus is on helping startups develop branding and design solutions to realize their product design vision. In addition to his work at Nike and various other clients, he is the main reason anything gets done at EvD Media. He once wrestled an Alaskan alligator buzzard to the ground with his bare hands… to rescue Josh.