To begin, I disassembled and cleaned the entire horn by hand using valve oil and denatured alcohol. I then chem. cleaned the entire horn in simple green and phosphoric acid, stepping it up to muriatic acid on some slides and the casing block.
I began to remove the various dents in the horn. First I went after the dents in the crooks of various slides. Using a Ferree’s Driver, a dent ball set, a delrin hammer, and a draw plate, I managed to remove dents from all of the slides.
The bell and stem dents were removed using a number of different techniques. First, I used a roller and a bell iron to get dents out of the flare and rim. Moving up the stem, I began to use French Horn dent rods with removable dent balls to push and rebound dents out.
The further down the stem the dent is, the harder it becomes to access it without removing the bell. To get dents out from under the finger hook, I removed the finger hook and soldered on an Allied Dent Puller to force the dent out from the outside. I then used a series of dent balls on a string and shook them down the stem, removing dents as they went.
Once all of the dents were out, I turned my attention to the rotors. I first fit all of the rotors by eliminating play in the bearing plate, rotor length and spindles. Doing this ensures the rotor will fit perfectly and move smoothly, without making lots of noise as it goes.
Before installing the slides and assembling the horn, I found three broken solder joints near the casing block: one in the 3rd branch, two between slide tubes. I cleaned up each of the joints and re-soldered them into place.
After the rotors were fit, I began fitting and modifying a lever off of a different horn to fit this style of linkage. I made a new hinge rod using a metric die set and some stock hinge rod. I then made a washer out of brass to lengthen the hinge tube so that it would fit. Finally, I ground down the tip of the lever so that it would not hit the body as it passed.
I began modifying the stop arm of the 4th lever to receive a new linkage. I had to drill out the existing hole where the lever screw would fit and replace it with a bushing. I soldered the bushing into the arm and drilled it out. The hole was threaded and counter-bored to receive the new post.
Once the arm was set, the new lever was marked out and drilled. I cut it down to a manageable size and buffed it to match the other levers. The threaded rod between sockets was measured and cut. The sockets were then greased and the new system installed.
Once the fourth lever was set, it was quick work greasing all of the slides and oiling the other rotors. The horn was assembled, strung, wiped down and play tested. The case was vacuumed and the project was turned in for grading. For more information, leave a comment or email me at airbandrepair@gmail.com.
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