Trumpets, being made of brass, can dent easily---whether the instrument happens to land on the pavement of a schoolyard during rough play or is accidentally dropped during a rehearsal. Dents can affect the tone and quality of the instrument. Removing the dents from a trumpet requires skill and technical mastery, as well as specialised tools.
Dent balls help push up dents in the trumpet and act as an aid in hammering the dents out. A complete set of dent balls will include a variety of sizes, ranging from 1/4 inch to 3 inches in diameter. Precision machined from quality steel, these tools are designed with the diameter and length increasing in size proportionally in increments, maintaining a constant shape from the smallest to the largest. Dent balls have holes through their centre with threads for attaching dent rods.
Dent rods allow you to insert the dent balls into the instrument. Machined from rust-free stainless steel, they come in a broad range of curvatures and sizes. The two standard sizes of dent rods for use on trumpets measure 1 inch in diameter by 48 inches in length and 3/4 in diameter by 48 inches in length. The tips of the dent rods have threads to allow them to fit into dent balls.
A set of dent hammers will include a variety of sizes and heads. The size of the hammer required will depend on the severity of the dent. Light-duty dent hammers have smaller heads, measuring from 3/8 inch to 3/4 inch in diameter, providing a sharp radius for working in tight areas. Heavy-duty dent hammer heads may measure up to an inch in diameter and will deliver extra impact. Ideally, dent hammers should be precision machined from noncorrosive rust-free steel. The heads should be buffed to a high mirror finish to prevent damage to the instrument while working.
A bell mandrel is a specialised mandrel made from cast iron or precision machined from steel. Narrow on one end, it flares out to accommodate the trumpet's bell on the other end. Inserted into the bell of the trumpet, it works in conjunction with burnishing tools or a dent hammer to remove dents.