Combined (Cascading) Mistake

In most cases a model maker does not have to be deadly precise. A tolerance for single part or element might vary from 0.5 mm (0.020″) to 1mm (0.040″). A tolerance may be even bigger for larger models and components.  Considering that a minimal reasonable thickness of an element and a wall limit usually should not be less than 0.5 mm (at least model maker has to try to keep it that way), you don’t have to worry very much about a single mistake. Let’s emphasize the word “single” in this last phrase, because there is a treacherous phenomena known as a “combined” mistake, which must not be underestimated nor overlooked.

A combined mistake is a summary of series of single mistakes in self-repeating elements lined up to create a whole part or element.  A single mistake alone might be sometimes microscopical, which often makes it very difficult to compensate for. That single mistake, however, multiplied by number of self-repeating elements is resulting in a combined mistake in overall dimension, which might be quite significant and compromise the whole part, element or an entire model. A combined mistake is like a snow ball – the greater the number of self repeating elements, the more significant a combined mistake will be.