Measuring bells

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To provide the equipment and mounting hardware to fit your bell, we need good measurements. Photos of the tower and closeups of the bell are also helpful.

Survey forms

PDF file downloads are available on our Bell_survey_forms download page.

Fill out one form per bell. In addition to the dimensions, be sure to include the following information on the form.

  • Location name, city, state
  • Your name
  • Date
  • Number of the bell (largest = bell number 1, smallest = bell number [total bells])
  • Foundry (if found on the bell's inscription)
  • Date bell was cast (if found on the inscription or other historic documents)

Survey tools and equipment

  • Sharpie pen
  • Chalk
  • Tape measure or carpenter's rule
  • Straight edge as long as diameter of the bell's mouth
  • Adjustable square with level
  • Magnet: if it sticks to bell, it is not a bronze bell
  • Optional laser measuring devices are useful if you are familiar with how to use them in tight places
  • Optional dial caliper for bolt measurements
  • Optional exterior caliper for finding thickest part of sound bow: strike point
  • Camera (smartphone) for tower photos, closeups of the inside top of the bell and any inscriptions. Use chalk to indicate bell number in photos.
  • Audio recorder (app on a smartphone) is important if we are automating a chime or carillon so we provide an appropriate music library

Measurements

Refer to bell ringing components to identify the components described in this procedure.

Parts of a bell

Clapper or hammer

Hammers strike on the outside of the bell, and should be able to impact the bell without striking on any decorations. Clappers will strike on the inside of the bell.

It is sometimes difficult to achieve good results when using an inside clapper on American bells that have a wide mouth with a narrow waist. For these bells, a hammer mounted either on the beam above a stationary bell, or on the floor below the bell will give the best results.

Mouth

Dimension A is the large diameter taken at the mouth of the bell. Hook the measuring tape on one side of the bell and move it back and forth on the opposite side until you feel you have the largest point under your thumbnail. Take the reading there.

Inside height

Dimension C is the internal height of the bell from the lip to the actual surface of its ceiling. If the bell has a headpiece, you can measure to the headpiece surface, but then add the thickness of the headpiece before recording the measurement. Hold the measuring tape as vertical as possible and measure down to the straight edge held across the bell's mouth.

Strike point

This is the sweet spot that we want the clapper or hammer to impact the bell. This is always the thickest part of the bell near the bottom, called the sound bow. For replacement equipment, you can usually see the spot on the bell that the existing clapper has been striking. Use a sharpie pen to put a cross hair in the middle of this spot to make all measurements to the strike point. Sometimes previous clappers did not strike in the proper location. The thickest part of the sound bow can be confirmed by sliding an external caliper up and down the lower portion of the profile of the bell's lip.

  • Height - Dimension H is the height of the strike point up from the lip. Hold a straight edge across the bell's mouth and measure up from it to the inside strike point with the adjustable square for the most accurate measurement.
  • Diameter - Dimension B is the inside diameter of the bell taken at the inside strike point height H. If you provided H for the outside strike point because you plan to use a hammer, mark dimension B as EXT.

Head

The part of the bell that is supported by the mounting hardware.

Dimension E is the thickness of the bell's head surface. Use the straight edge across the lip of the bell and measure from the bottom of the beam to the straight edge for the overall height of the bell, then subtract the inside height C.

On the outside of the bell it may have a

  • Flat top - Dimension J is the diameter of the mounting surface area
  • Conic top - measure the height of the cone, its large diameter and its small diameter (if not fully exposed, measure the bottom diameter)
  • Crown top - we have a separate survey form for these measurements

Dimension F is the mounting bolt diameter.

Dimension G is the mounting beam thickness. We will provide bolts long enough to use double nuts. If clearance above is not an issue, you may overstate to obtain longer bolts.

Dimension I is the inside diameter of the existing headpiece or the indented portion of the bell's ceiling meant to support the bell.

Shoulder and waist

Dimension D is the inside diameter at the top of the bell. This is helpful to prevent interference with the mounting of the striker.

If the waist seems to suddenly flare at the bottom, take an additional inside diameter measurement near the flare with the height of that measurement up from the lip.