Higher tolerance “insurance” comes with a price tag.
There’s an old rule of thumb among suppliers of precision gages that tighter tolerances mean higher prices. This is understandable considering the extra effort involved working within such boundaries. But not all gage users understand this. They want lower prices (always) but when the gage maker suggests that a more appropriate tolerance could result in cost savings, buyers tend to shy away. Having sold, manufactured and calibrated gages for over fifty years, these situations keep arising. I hope a look at the bigger picture may be useful.
The situation comes up quite often when the customer’s product indicates a gage tolerance of 0.000l inch, for example, but a tolerance of 0.00005 inch or less is specified. The tighter tolerance is called up as insurance because the person specifying the gage is not conversant with the process. And they usually don’t consider the implications of doing so further down the line.