I know there has been some chatter about using Belleville washers rather than split lock washers for more uniform (and calibrated) distribution of force and I’m curious to know whether anyone has put that into practice.

I’m also interested to understand what specs for a Belleville washer would make it appropriate for this application (of holding down lugs/busbars onto 280Ah terminals).

Since we are aiming for ~35 inch-lbs of torque, I suppose we’d want a washer that reaches at least twice that at it’s point of maximum force near half-deflection.

Has anyone done the conversion of 35 inch-lbs of torque on an M6 thread to the specs we’d need on a 1/4”, 5/16”, or 3/8” Belleville washer?

And on that last point of diameter, and configuration in general, interested in thoughts on what would be best.

After playing with Belleville washers for a 390kgf fixture, I’m actually concerned enough about interaction of the edge of the washer with threads that I’m thinking larger than minimum would be better. Among other things, a larger diameter hole is going to distribute the force over a larger area.

So my thoughts are:

-terminal is 15mm diameter so I want a washer whose central hole is at least 10mm so the force is applied over a large area (and the washer is nowhere near the grubscrew threads.

-Belleville washer placed upside-down (cone-up), followed by a large M6 flat washer (larger OD than the Belleville so it completely covers the outer edge).

-M6 nut tightened down until 35 inch-lbs (or a calibrated number of 1mm M6 turns if you trust your washer specifications more than your torque wrench.