We present an approach of a shear force based touch interface that provides a way of actively changing the possible shear-based input (force tangential to a screens surface) by physically locking the corresponding axis of the device. This approach of actuated shear aims at using shear not only as input, but to create a new form of output modality that changes the input affordance of the device itself. It enables a new channel of incorporating physical information and constraints into touch-based interaction (i.e., by changing the input affordance of the device and using shear as a feedback mechanism). With this actuated shear approach, we create a coupling between the digital context created via touch and the actual physical input affordance of the device. Based on the implementation of a prototype, we discuss the design space of actively changing the input affordance of a shear-based touch device, sketch interaction ideas as well as future application scenarios and domains.