Page Comparison

...

Using these settings in relation to our example job, recall that the desired edge thickness was 1.5mm.  These settings mean a finished lens could be between 1.2mm and 2.3mm thick at the minimum edge, and be acceptable.

Thinness and thickness tolerances can also be set on the material and on the lens style.  In both of these cases, a value of 0 indicates that the value isn't being used on the material or lens style (default to system settings or the frame type):
Image Added              Image Added

Since Safety jobs often have different rules (they usually cannot be thinner than the calculated minimum), there are separate thinness and thickness tolerance for Safety jobs, as seen here.

Other frame types may also require different settings. Within Withi473pxn the frame type setup, the lab has the ability to set different tolerances for the frame type, by material type:

In this example, a groove frame type has different settings for different material types.  A poly lens could be up to 2/10 thinner than the 2.2 minimum edge specified for this frame type, and up to 1.0mm thicker.  These parameters will change depending on the lab's preference, the equipment being used to groove, the experience of the operator (if doing manual grooving), and what the default thickness is to start with.  For example, if a lab wanted the minimum edge to be 1.8mm for grooving, a finished lens probably could not be any thinner.

The priority / precedence of the settings is as follows:

1. use system settings to set the default thickness and thinness tolerance (the "current" tolerance)
2. if the tolerance is set to a value other than 0 on the lens style, and the value is less than the current tolerance, set the "current" tolerance to the lens style tolerance
3. if the tolerance is set to a value other than 0 on the material, and the value is less than the current tolerance, set the "current" tolerance to the material tolerance
4. if there is a frame type, and the tolerance is set on the frame type, and the frame type tolerance is LESS than the current tolerance (even if the frame type tolerance is 0), use the frame type tolerance

While the discussion herein discussed minimum edge thickness for plus jobs, the same rules and logic apply to minimum center thickness when considering finished lenses.

...