The Useless Hammer

The useless hammer has been a funny way for us to put in application the different skills we learnt during the PROTY class. We wanted to build something that answered to a human interaction so we thought of a hammer that hits your finger when you press a button. 

We had very different ideas of how to hit the finger that pressed the button, but the most simple way was by using a servomotor.

As we wanted the users to press a button to be hit, the only solution was to use a pressure sensor for the captor.

We wanted to have a nice looking hammer, so we looked for interesting designs on the internet in order to print it in 3D. 

We then designed the whole box containing the Arduino components and the pressure sensor according to the hammer’s dimensions. The box also had to be large enough so we could fit the Arduino card and the breadboard inside. 

You can notice a recess in the rectangle: it is the spot where the servomotor comes. We also had to put the pressure sensor at the same height as the servomotor’s axis so that the hammer could hit the user’s finger in an horizontal position.

The code is quite simple.

The hammer is originally in a vertical position. A threshold that represents the moment someone presses the captor has to be determined, and when this threshold has been exceeded, the hammer goes down by 90° on the finger and comes up back to its neutral position.

During the project, we faced a major problem which was the miss-conception of the box. It was originally a rectangle, and when we first did the pocket operation on Catia in order to create the room to put the Arduino card and the breadboard, we did not make it with the correct measures, so no component could fit in the box.

We had to redesign it with the correct dimensions. We also added a little hole so we could put the pressure sensor from the inside of the box in order to hide the wires.