A set of 3 Premier fibreglass concert timpani to be over hauled. The usual problem with Premiers – the bowl shifts in the chassis. This is a bad example where the bowl is actually being pulled into the inside of the suspension hoop. These types of issues will affect the tonality across the playing range but one part of the range may well be in tune.
Cleaning of the old, incorrect, counter hoop felt and glue residues ready to be replaced correctly. First the hoops will be checked for loose parts and that they are flat and round. After final clean, new felt will be inserted. The counterhoop is like the nut on a string instrument, bad implementation will create a vagueness in the note.
The counter hoop (above) is not flat. This is a universal problem with counter hoops. In application they bend down at the tension bolts, this means that the tension being applied to the drum head between the bolts is less than at the bolts. The bearing edge or rim of the bowl in acoustic terms is a nodal point, where the amplitude of a sound wave is zero. The centre is an antinode, where the amplitude of the sound wave is greatest. In order to achieve a harmonic note in a membrane (drum head), the nodal point needs to be round. Therefore, the effects of the counter hoop flex can best be visualised in the diagram below:
The variation in tension has created a wiggly edge to the nodal point. This creates problems when putting on a head and clearing it (removing overtones).
The distortion can be minimised, but I have yet to definitively solve the problem, only achieving up to 1/2mm out of flat depending on where the hoop has bent.
Pedal casting dressed & nylon inserts reamed so that the pedal fulcrum spacer can be gripped firmly between the pedal arms without inhibiting the pedal movement.
The fork pressing cleaned, lubricated and the fork casting dressed to ensure squeak free smooth operation.
The adjustment screw barrel nut tapped, de-burred and lubricated to ensure easy adjustment and smooth movement.
All three elements allow the pedal to operate without resistance; the pedal return pressure is provided by one spring inside the clutch mechanism.
All the work here is aimed at making the pedal operation smooth and resistance free, and to enable the whole assembly to be stiffened. Therefore decreasing friction in the vertical operating movement whilst minimising horizontal play.
My aim is to improve feeling whilst playing, assist the function of the clutch mechanism and facilitate greater accuracy in instrument set up which in turn improves quality of tone.
New aluminium shoes have been welded onto the foot of the base casting, and now the chassis are ready to be cleaned and painted. As the drums are moved, the casting wears down which lowers the front to the point where the pedal mechanism fouls the floor. Screwing on a plastic pad is a temporary fix, but the problem is that the force applied to the pad is shear, and that is the weakest aspect of a screw. Once the screw has snapped, your left with removing hard steel from soft aluminium.
After the chassis have been worked on, and the set up done, everything is ready for reassembly.