Band Instrument Repair: Tools for Success: Dents

Trombone Buckle

Buckles are a part of band instrument techs endless dent repair. A buckle can be defined as an instrument where the throat is out of round and may have lighting bolt creases. A buckle can also have a bell fold but in order to fix the bell you have to work out the buckle first. The best tool to start fixing a buckle is a dent roller. First I needed to go after the creases and have the roller inside the bell. It is best to work out as many creases from the inside before moving to the outside. When rolling the outside of the bell it is important to avoid rolling the throat because the bell is out of round and then there will be a false sense of round. Once the bell is coming back to round I had to hammer some of the creases. When hammering it is important to ask yourself "do I need to be hammering?" Hammering can thin the brass so it is important that you make sure you have to hammer. The finishing step in buckles is to make the throat round and the rim flat. These can be accomplished with hammers, rollers and burnishers. Another technique that can be used is called ironing. This is when I used a bell iron in a vice, placed the bell on it and placed a roller inside the bell. Then I made sure the roller was in contact with the bell and the iron and moved the bell and roller back and forth. This technique is called ironing and helps smooth out the imperfections in the bell.

Trombone bell buckle

Large crease in side

Throat is out of round

After using the roller

The brass is has some scaring but it is restored

Restoration is done but the brass will always be stretched

Trombone Bell Dents

The first type of dent that I worked on in class was a trombone bell dent. These dents were surface ping dents that could be removed with a dent roller. I learned how to place the bell parallel to the florescent light to show the imperfections in the bell.

Ping dent on trombone flare

This dent was an outside dent going to the inside of the bell. For this type of dent I used the dent roller to press the dent out. As I used the roller I kept inspecting in the light to see if the dent was back to surface. Another tool I used was a piece of blue cloth and a light touch to feel any imperfections. Just by using touch I was able to find imperfections that I could not see.

The dent was removed successfully!

Crook Dents

The next type of dent that I learned to remove was a crook dent. I was given a second valve slide crook that was dented to work on. In order to take out crook dents I need to use dent rods, dent balls, and multiple hammers. When starting on a crook dent it is important to use the largest tool that fits under the dent to fix it. While removing the dent it is important to see the dent, only work the dent, use lubrication, and follow the arc of the part. I worked on dish dents and crease dents on the crook. When starting dish dents it is important to use a large dent ball and work the dent. For creases it is better to use a small dent ball because there is a definite point of contact that I am trying to make.

Second valve slide crook dish dent

Second valve slide crook crease dent

Dent rod and ball

Preparing to take out the dent

Dish dent removed

Crease dent removed but the line still exists because the lacquer is damaged

Bell Folds

Bell folds usually happen when a trumpet is dropped on the floor when a player is not being careful. The tools needed to take out a fold are: bell forming iron, dent roller, a machined flat surface, a rubber mallet, rawhide mallet, and dent hammers. Taking out bell folds can be a tedious project. First I used the bell forming iron to reshape the bell. Then I used the machined flat piece of granite to make the bell even. After that I used the dent roller to remove the crease left from the fold. Once the crease was removed I used multiple typed of hammers to remove dents from the flare and the edge close to the rim. Below are pictures of the dent fold removal process.