Turn the handle on the side of this box and the vertical shaft sticking out of the box top twists from side to side. I’m calling it a Rotating Reciprocating Vertical Shaft mechanism or RRVS. Perfect for a shaking head mechanism such as the Disagreeable Sheep or the Watch Mouse. I have a couple of small changes to make then I’ll be releasing this as a mechanism as well as using it in a Disagreeable Dog model.

From underneath you can see that the mechanism is a modified version of the Intermittent Rotation mechanism with an extra cam.

Looking at the underside of the box top you can see the two stops which limit the rotation of the vertical shaft.

The drive plate on the vertical shaft has stops on the top side to match with the box top stops.

The drive shaft has two cams. Each has a cut away so that the drive plate on the vertical shaft is turned alternately clockwise then anti-clockwise.

The various parts all fit together in the box and are driven via a handle at the side.

To try out the mechanism I’ve added a connector to the inside of a guard dog’s head. The eight millimetre square tube fits neatly on the circular vertical shaft.

The body sits over the vertical shaft lined up so that the head will be centred over the body.

I’d say it was looking good but if I turned the handle it would only disagree.

I’m also trying out an owl to go with the intermittent rotation mechanim. This one is looking a bit underweight Might be better with a slightly conical body.