Precision Pendulum Assembly

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This page is intended to serve as the assembly instructions for the Precision Pendulum, particularly following the setup developed for the WPA project. This page starts with a brief description of the apparatus and its core components. Then it is followed by the description of the assembly process which is divided into three core parts: the mechanical assembly, the electronic controller assembly and the setup calibration. An additional step is described for those who want to allow "non-remote" operation (ie: local operation in a museum or common area with public access).

Order of assembly

Although not critical is recommended to follow this recommendation list in order to proper assembly the structure. This list only refer to the main points that shall not be neglected and highlight the most leave-out aspects:

  1. Assemble the main structure according to the instructions on page Mechanical assembly, filling up the tubes with small grained sand but only to 2/3 of their height after being tight to avoid sand leakage. Conversely they can be taped in the interior with a small cardboard disk.
  2. Keep the screws loose (only hand tight) during the alignment; only after setting up the complete structure and proper calibration they should be tighten.
  3. During cable measurements take the fulcrum out of the rail (cable off-centered) in order to measure the exact length by having it on the parallax plane.
  4. Excite the pendulum by hand very gently to define the exact plane of natural oscillation and use the screw nuts on the launcher to perfectly align the launcher with it direction; before doing it have a flashlight and paper screen on opposite sides of the launcher to perfect align the oscillation plane. With this technique the wire shadow should not move from the center of the screen paper.
  5. Use the command "laser on" to align the laser; the laser can be focused by rotation the lens on its case if the beam became quite divergent.
  6. To do the calibration of the shovel movement, use a long displacement such as 300mm to 400mm to reduce systematic errors. Issue in sequence the commands "go to origin 5 5" to read the axes origin reference, then issue "move forward 40 2 2" to slowly move the shovel 400 mm. Lastly take note for the vertical position and maximum position. This 4 values are of extreme importance to calibrate the experiment.


  1. Apparatus description
  2. Mechanical assembly
  3. Electrical interfaces
  4. Software management
  5. Calibration
  6. Partners