Question

what is the most important maintenance on a circular saw? lower blade guard blades sharpness battery charge upper blade guard

Explanation:

A sharp blade on a circular saw ensures efficient cutting, reduces the risk of kick - back (a dangerous situation where the saw is thrown back at the operator), and provides a cleaner cut. While blade guards (both upper and lower) are safety features, their proper functioning is more about safety during operation rather than the most crucial maintenance aspect related to the saw's performance. Battery charge (for cordless models) is important for operation but not as critical as the blade's condition for the saw's effectiveness and safety in terms of cutting performance.

Answer:

blade's sharpness