Fadal has used resolvers as the primary feedback device since their first production DC servo machines in the early years. While they are considered a "consumable item," they are built to be reasonably durable and highly accurate when using an analog three phase sine/cosine signal.

Unlike the newer digital encoder counterparts, the resolver has infinite resolution and the potential of superior surface finishes (all other factors being the same within the machine over encoder feedback systems). The main difference is that encoders use digital (ones and zeros) signals, and resolvers use analog signals, much like the difference between the old CD's vs Long Play (LP) Vinyl Albums. Sample rate has much to do with resolution in CNC's as it does with CD players for sound.

Resolvers contribute to surface finish problems from two angles: mechanical wear and electrical signal weakening.

Replace them about every 2-3 years and you will stay out of trouble.

Installation Tip: Place resolver on motor stand-off resolver mount. Push firmly into the indent and screw down all three clamping screws tightly. Now proceed with tightening the resolver/motor coupler to the resolver shaft. This is the last step. If you reverse the order of this process, you will put excessive preload on the resolver end bearings and premature failure is imminent.