A bell is tuned to five partial tones, spanning two octaves. The "strike" note, which is heard on the impact of the clapper and the "hum" note, which swells up afterwards, are the two most evident to the unpracticed ear, the others being the minor third, the fifth and the octave above the strike.The hum note should be one octave below the strike.

As well as being in tune with itself, each bell must be in tune with the others in the ring, so that the ring functions as a single musical instrument. The bell is cast as near as possible to the required note and the final tuning is done by removing metal from inside on a large vertical lathe. When tuning hand bells the margin of error is so small that even the polishing needed to give the bells their gleaming finish must be allowed for.The strike note alone was tuned, the rest being left largely to chance, until early in this century, when Canon Simpson re-discovered the principles of harmonic tuning, used   by  seventeenth century   Dutch  founders but not exact, (nowadays verified electronically) since that time Continental founders have only adopted the method since the war.

A harmonically tuned bell is not automatically a good one. The quality and roundness of its tone depend equally on the thickness and weight of the metal and on the acoustics of surrounding spaces. The first tuning machines were steam driven that revolved around the stationary bell. On present lathes, it is the bell that turns.