Recently in the shop we have come across several instruments that have the incorrect screws in the posts or guards. We are here to tell you that NOT all screws are the same and they are definitely not interchangeable.
There are multiple types of pivot screws. Pictured at the top of the post, these are (from left to right) a headless point pivot screw, a headed point pivot screw, and a pilot pivot screw. Keys that are attached to the instrument using pivot screws have a specific interior casing to match the corresponding screw. The keys will not work efficiently if you are not using the correct end. In addition the threads are more than likely not the same either.
Another type of screw is the hinge screw. On this type of screw the key has a hollow tube that the steel rod runs through. Hinge screws are the most difficult to maintain if they are bent because we have to straighten both the bent screw and also the bent hinge tube. Also, it is important to keep these types well oiled because if moisture creeps into hinge area the entire key can become rusted.
The final type of screw is the guard screw or body screw. These screws look the most like a regular hardware screw but do not be deceived. They do have specific threads that can be easily damaged by installing any old screw. Once the threads are damaged, the guard and/or body are irreversibly changed.
In conclusion, if you lose a screw look around for it. Search your case, the floor, the room you are in. If you find a screw and it does not easily install back in the instrument, do not force it! Also, keep all your screws well lubricated. Keeping key oil on the mechanisms will help repel the moisture and ensure that they rust stays away.
If you have any questions feel free to call us at the repair shop! Have a great week!