Exceeding Tolerance

July 20th, 2010 by k8gu Leave a reply »

I read IEEE Spectrum via my Google Reader (and, as an IEEE member, in hard copy).  One of the disappointing things about Spectrum is that it’s written predominantly by people who are science and technology writers, not actual scientists and engineers.  Therefore, it’s a little more sensational than what I’d like (I can read that stuff in Wired).  But, I digress.  I was pleased, however, to see an article today entitled Low Tech Fixes for High Tech Gizmos.

The author wistfully lists all of the things she’s fixed with duct tape and hot-melt glue…

This is really anecdotal evidence of the fact that many non-catestrophic device failures are due to failures of tolerance.  That is, the device (or some of its components) are operating outside their expectations in the design.  This is especially true of mechanical tolerances in low end injection molded consumer devices.  As manufacturers seek to save more, tolerances get tighter.  Cleaning, replacing batteries, disassembly/reassembly, etc, are all examples of the same class of repair.

I just repaired a toy boat for Sarah’s cousin’s son tonight.  It had dead batteries and a gear was pressed too far onto the motor shaft causing the motor to stall.  It’s a good reminder to look for the tolerance failures, even if that sounds like obvious advice.