I am continuing to struggle with the hardened fulcrum knives. It’s been to the point where I have devised a different design, relying on ball bearings instead. I have tried two versions of bearings: one with steel balls and one with ceramic. The results to date are inconclusive, but I think that the response of the strings (i.e. sound) is significantly better with the knife edge.
Having said that, I want them more durable in a product.
Here is the hardened version that I just received, after only a few minutes of playing:
And the ball-bearing prototype:
I have returned the hardened knives to the manufacturer, hoping that there is something that can be done to improve the performance. I will try to organize some comparative sound samples of knife vs. ball-bearing to see if the difference is real or imagined.