In both checking finished work, and laying out work, it is necessary to check that parts are at right angles to each other, or are at a particular angle to each other, and that dimensions are correct. The combination square by its particular design and with special accessories, can check squareness (right angles), check other angles, and can lay out lines at right angles or at other angles. Its real versatility is that it can also draw lines that are offset a distance from an edge, draw vertical (plumb) lines, draw lines at an angle to the horizontal, and find the center of a shaft. The precision version used by machinists and cabinetmakers is accurate to 0.001" in 12", which is adequate for most ordinary work.

Professional Engineer and Museum Volunteer Bob Timmerman will describe a combination square very similar to the ones in the measurement exhibit, and demonstrate the use of the combination square in several common layout and checking tasks, in both wood and metal.

Mr. Timmerman holds Bachelor of Science and Master of Engineering degrees from Cornell University, both in Mechanical Engineering.  He is a Registered Professional Engineer in Massachusetts, New Jersey, and Pennsylvania, and holds 3 U.S. Patents on innovations in recycling the reject heat from power plants.  He has over 40 years’ experience in energy engineering.