Step 4: Bed and Lever
Design a bed in good proportion with your figure. We chose to go with a bed that had feet so you could see the mechanics underneath, but there is no reason this is necessarily so. Cut a hole in the bed to insert the lever through at wherever you'd like the bottom of his torso to be. Size this hole to fit your lever, which will be addressed in a moment. Once you've figured out the position of your wooden figure, drill a hole to match the one in the back of the torso. While the adjoined picture has small blocks to prevent the torso from sliding toward the foot of the bed, if your level hole is sized well to your lever these blocks prove to be more trouble than they're worth. Also, be sure to leave room for the figure's head.
The lever requires some design questions. The basic idea is just a beam with an S-bend in it at the hole in the bed, but certain elements like the width of the bed are important. Do you want the motor to push or pull the lever? Do you want the bed raised above the floor or a protrusion of the contiguous floor? In our case our servo pulls and our bed is raised. This meant our S-bend didn't need to be all that significant, since it merely needed to get below the bed but above the floor. One need be cautious with the material selected for the level, though, as all the force in the product will be directed through it. If you're not using a very strong wood (as we weren't, using Basswood), you need to compensate by making it thick enough. Our quarter inch version snapped, so we upped it to a three eights. The snapped quarter inch version is featured below.
Once your bed and lever are constructed, begin assembling the pieces in the bed. Make sure you can fit the lever through the hole in the bed before gluing it to the torso (shouldn't be an issue). Feed the fishing line through the bed and achieve a tightness that causes arm extension at the point in the arc of sitting up that you'd like. We secured the fishing line with knots and electrical tape. Adding a piece of cloth to the bed gives an illusion of a mattress. At this point you should be able to make the man sit up in bed and extend his arm just through use of the lever.
Our laser cut pieces for the lever and bed can be found attached.