Want to design mechanisms that will never jam?

This page and video will cover the topics of guide ratio and sensitivity and a few simple principles to make robust mechanisms that will never jam.

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Robust Design Principles

Guide Ratio

Robust Design PRinciples: Master Guide Ratio and Sensitivity

Guide Ratio to Avoid Jamming

The simple equation to remember to ensure that a slider mechanism will not jam.
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• Ensure that B/2A is greater than the friction coefficient between the slider (blue) and the frame (grey).

Optimize Guide Ratio

The rule of thumb to ensure the best sliding capability of a slider with as little friction as possible (and with minimum variation):

• Minimize A (ideally move the point of attack to the center).
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• Maximize B (increase the distance as much as possible).

Understanding Sensitivity

A sensitivity analysis reveals sensitive parameters in a design/calculation.

• The sensitivity value represents a gradient/slope for a parameter in an equation.

• It is calculated by adding variation of 0.1 (absolute) to a given parameter and comparing it the end result.
In example a sensitivity of 80 corrosbonds to a 0.1 unit change in the given parameter, then impacts in a 8 unit change in the end result. A sensitivity of 20 corrosbonds to a 2 unit change in the end result.

• Sensitivity studies are useful to identify tricky parameters and it is always adviced to try to lower the sensitivity as much as possible by all parameters.