In Shapr, simply dragging the centerpoint of any object with the move tool to the rim of a circle will center the point.
I would draw a single tooth by making sure the left side and right side profile of the tooth were a proper even fraction of 360 degrees where they crossed the circular core.
Then select the extruded tooth and drag the Move tool centerpoint to the edge of the circular core which will cause the tooth centerpoint to snap to the center of the circular core.
Then drag off a copy with the rotate arrow and type in the precise number of degrees between teeth. Then do this again only selecting Both teeth and dragging the centerpoint to center and dragging a copy off twice the number of degree used prior.
Do it again with 4 teeth. then 8, eventually you get to where you have All the teeth in a 6th, or fifth or even quarter of the gear circle, at which point you select them all, center to rotation point, and drag off 6, or 5 or 4 copies to complete the circle.
It’s annoying and the app really does need a simple repeat function to replicate a Copy/Move action to streamline this… but centering drawings and objects is actualy one of the things shapr does best.