Some years ago I received an old Saw Filing Guide from Briggs & Shultze patented September 1919.
I didn’t work often with this guide, though the adjustment is repeatable.
The handling is a little bit too fiddly.
I tryed to recreate the guide, but fortunately Veritas was quicker.
In my mind I turned the guide around and now the prototype of my Ultimative Saw Filing Guide is ready.
The File Guide is designed for needle files. These files are fixed very tight with a set screw . To adjust the rake a small gauge is prepared. It is quite easy. 
The adjustment of the gauge is done by opening the wing screw and setting the required size on the scala. The filing guide is laid on the top of the gauge with the set screw opened, the guide is turned till it is horizontal and the set screw is fixed. Fleam adjustment is self-explaining, the new guides are fitted with a scala.
To adjust the slope I swivel the saw vise in the end vise of the bench. So it is easy to keep the file leveled.
