I have just received a copy of the Robert K. Waits book Before Gillette The Quest for a Safe Razor Inventors and Patents 1762-1901The book is A Safety Razor Compendium by Robert K. Waits. I found my copy on Amazon. I have a HR-14B model and I use the wedge adapter from Frugal Shave on Etsy and a unmodified gem blade in mine. This works well for me.
A wonderful enlightening book.