Screwman1
Helical lock washers have such a low spring rate that before they start to return you will have lost about 90% of the clamp load in the joint and if that happens, you have a failure going on. If they are fully flattened, then all you have is a hardened flat washer- so use one of those instead.
I would never recommend one at work and I take them off things around the house.
A waste of time and money and one more component that can be left out of the assembly.
They seem to be unavoidable in all sorts of commercial equipment (lawn tractors, stoves, bench grinders, etc.)
I reuse them when doing so allows the same bolt length to continue working. I never use them when doing work I am being paid for. Except… some electrical standard practice manuals require them on electrical bonding terminals.
Oh indeed I can, and the star-lock washers come in a variety of military specifications (points on the outside / points on the inside) that I prefer to use when I can. But for doing work on old airplanes, the maintenance book says what the maintenance book says, and there ain’t no more Fokker, Lockheed, or Swearengen to rewrite them to a more modern standard.
The Bellvilewashers are mostly used on current carrying connections. The purpose is to maintain contact pressure during heat/cold cycles, not to prevent loosening.
I could be wrong, dik, but I understand that they are more for constant pressure and resilience than for high clamping pressure.
In some installations they are stacked to increase the clamping pressure.
They are excellent for coping with heat expansion cycles.