When to use a Start Depth?
You would typically use a Start Depth when setting up a toolpath that will cut where material has already been removed by another toolpath. When applied properly, this can result in significant time savings when machining some projects.
A good example would be where a Pocket toolpath has already removed 6 mm of material and you want to cut text at the bottom of the pocket that will be 3 mm deep. In this case, you would set the Start Depth to 6 mm and the depth you want the text to be cut, 3 mm, in the Cut Depth.
Note: When you have used Start Depth in a toolpath, always be sure to run the toolpaths in the correct order. For example, running the Text toolpath before the Pocket toolpath in the above example could result in bit breakage or poor results as the Text toolpath is now removing 9 mm but with the same setup that was intended to only remove 3mm of material.