It might be best to use a blurred image, or a couple. If you really want to simulate the saw, you could create a path and a number of bones, then select the bones and create a path constraint. Set the path constraint to Tangent under the mix settings, then set the offset rotation to 90. It'll look something like this:
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Then you can animate the path constraint position to make the teeth bones go around the path.
Docs:
Paths - Spine User Guide
Path Constraints - Spine User Guide
