Constructing the Load Cell

• 1). Drill two holes in the sides of the metal cylinder approximately 12 inches from the base of the cylinder.
  
  
• 2). Tap these holes with the thread cutting tap. Thread one pressure gauge into each hole. Seal the threaded stem on the pressure gauge with Teflon thread sealing compound. Allow the thread sealing compound to dry before proceeding.
  
  
• 3). Fill the rigid metal cylinder with hydraulic fluid to a height within 1 inch of the top of the cylinder.
  
  
• 4). Fasten the smaller round aluminum disk to the top of the aluminum piston with epoxy adhesive. These two disks should be concentric.
  
  
• 5). Measure the weight of these two aluminum pistons. Record this initial weight measurement for use in the calculations to follow.
  
  
• 6). Wet the rubber O-ring around the edge of the aluminum piston with hydraulic fluid. Insert the piston into the metal cylinder, making contact with the hydraulic fluid. The top surface of the aluminum piston should be level with the top rim of the metal cylinder. The smaller disc should extend above the rim of the metal cylinder. Adjust the amount of hydraulic fluid in the cylinder accordingly.
  
  

Calculating Weight

• 1). Record the initial pressure readings on both pressure gauges. These readings should be identical. If any difference exists between the two readings, take an average of the two readings for the initial pressure value to be used in calculations.
  
  
• 2). Place the new object on top of the aluminum piston. The weight of the object will increase the pressure of the hydraulic fluid in the metal cylinder tank. Record the second pressure value for the following calculation.
  
  
• 3). Calculate the weight, or mass, of the new item using the following formula:
  
  Mass(new object) = [Pressure(second) * Mass (initial piston)] / Pressure (initial)