On reading this, I really wondered what all the fuss was about, surely if the threads of the 1912 and a standard DE razor are the same, it should be easy, It actually took me genuinely under 10 minutes from start to finish to do it - here's how...
Pop into your garage/shed, get your tub of bolts out that you bought in your local £Pound store...
Find the one with the correct thread that screws into the DE handle, as well as the 1912 razor head. Then, cut off the head using a hacksaw. If holding in a vice, wrap well in cardboard to protect the thread, it should look like this... It may be necessary to grind of the edge to remove any rough bits.
Then you screw one end fully into the DE razor like so...
Then, the final stage, screw into the 1912 head until it's firmly seated.
The handle belongs to a Muhle R41, which I've replaced with a nice SS one, which I had just lying to hand, but obviously any handle will fit. I think following this tutorial, you'll find that Robert really is your father's brother
This is obviously going to be my shaver in the morning LOL