Repair guidance for hornists
Why this article?
As a conscientious maker of horns I´m very interested, that the buyer for a very long period will enjoy his investment. The life span of an Engelbert Schmid Horn can be almost unlimited, but also any other make can last very long at the right maintenance. Generally it’s a fact, that horns, and brass instruments at all, are rarely dying by being played, but are destroyed by repairmen who don´t know the correct craft. So many of them are “destroymen”. Why exactly by these “experts”? Because they never have produced a machine, never have had to fight for every single hundreds of a millimeter.
The principle of a valve:
In wet condition of the inside tightening areas the valve has to be airtight also at the air pressure in Fortissimo. For this the tolerance in diameter between the rotor and the casing has to be within 5 to 8 hundreds of a mm. We aim to constantly achieving the 5/100 mm which are the minimum for well running valves. New valves of good makers normally are so tight, that the instruments from the beginning provide a good ff. In the first 6 months the valves get even tighter because of the oxidation and lime deposit. This is one of the reasons why horns get even better after a certain blowing in time. The valve bearings need to have even less tolerance, the less the better. In diameter within 2/100 mm is ideal and possible. By this the valve is running only on the bearings, which always should have oil. If there is no oil in the bearings, condensation water and with it lime deposit may grow into the bearings. The valve inside is swimming in the condensation water respectively in thin valve oil. The bearings need medium thin oil, which does not evaporate too quickly. Most of the problems with sticking valves come from no oil being in the bearings, so allowing the access of lime deposit (the calcium in the lime deposit is a very bad lubricant), or from bearings with too much tolerance, that the normally calcium covered rotor inside can touch the also lime deposit covered casing.
How should you treat the valves, that they are running reliably and not get old? See the following good advices: Bearing oil in the bearings prevents from wearing and contributes a lot to reliably running valves. Oil once per month, in hot summer months every 2 weeks. Half a drop exactly into the corner between stopper and bearing at the actuation side. At Engelbert Schmid Horns you have easy access to the correct spot. With the needle of the oil bottle you easily hit the right corner. Meahwhile we have oil resistant silicons, which are silent and durable for years.
At the screw cup side the correct spot for oiling is at the air marks. At Engelbert Schmid Horns due to the geometric construction the oil is growing very well into the whole inner bearing area.
At this moment I would like to explain 2 methods of oiling, which both make sense:
A) Oiling only the bearings and not inside: This is the common German method, which in principle works well. But you have to develop a sense for the right dosage. If you oil the bearings too little, condensation water and with it calcium will grow into the bearing, what blockades the valve. If you oil too much, the not so thin bearing oil will grow into the inner tightening areas and will make the valve tough running, without blockade, but slow. The right dosage is a half or small drop once a month, in summer at hot and dry weather every 2 weeks. Advantage: At a little too much tolerance in the tightening areas the lime deposit with time will make the valve a little tighter again.
B) Oiling inside and outside: This is the common method in the United States. At Engelbert Schmid Horns you need not oil through the slides! You will hit exactly the right spot by oiling through the side hole in the upper bearing plate, without danger of washing in slide grease. Advantage: You may oil too much the bearings from outside, as you will dilute everything again by oiling inside. The spreading oil in the horn decelerates the red rot at yellow brass horns, the red points under the lacquer. Disadvantage: Due to the permanently present oil inside almost no lime deposit is building up, which would tighten up leaking valves a little.
Behavior towards your repairman:
Understandably, but unfortunately for many brass players that repairman is regarded as superb, with which the valves are running absolutely without noise and freely when the instrument is picked up. Often this results from enlarging the tolerance in an acid bath. This might go well just once or twice again, but at the next repair the loss of metal suddenly is too much and the instrument is repaired to death. Of course the valves must run without problems, but accept minimal grinding noise! It will disappear within a few hours playing. If you feel yourself skillful enough in craft, you may take out a valve yourself, clean it and insert it again. For this please read also the good advices for repairmen, which you find also in this forum! You need from the maker or repairman of your instrument the following 3 small items: A crank lever, a nail with filed down peak, ( ~ 2.3 mm) and a round piece of wood with a hole in the center. A light hammer and a screw driver you have yourself.
Take away the cup and the central screw at the actuation side, put the blunt nail into the screw hole and beat out the rotor carefully. Then you abrade the lime deposit in its own soup and wipe rotor and casing clean with a cloth. Oil the valve at inserting like described above! Its important that you knock the bearing plate back on the casing completely in order not to produce up and down play! At mistreated und so untight valves of the traditional brands there is no entirely satisfying repair. Enlarging the rotors by galvanization (rebuilding the valves) can provide an improvement for some time, but often does not provide the necessary tightness to the valve, and absolutely never gives back the original running abilities. To exchange the whole machine by a new one is expensive and often changes the instrument. At Engelbert Schmid Horns mistreated valves always are completely repairable, - for a reasonable price! At this machine system its possible without problem to exchange the rotors and the valve is rest into the new condition. In the rare case of too much loss of metal in the casings these are calibrated to 1/10th bigger and corresponding bigger rotors and bearing plates are inserted.
So, I should let the things slide with the repair methods? :-) No, - again and again it’s a pain for my soul to see, how long hornplayers labour away with inefficient, untight horns, and that they normally have to pay themselves for the not so inexpensive repair, because they cannot make anybody responsible for that.
