Chuck Taylor via OldTools wrote:
>Tom Fidgen of "The Unplugged Woodshop" claims to have invented the 
>"kerfing plane":  [...]
>He said that the reason he invented it was to cut a kerf around a 
>board in preparation for resawing by hand. Sure looks a lot like the 
>Whitaker Patent Saw-Rabbet Plane.

Yeah, I'm a little suspicious of the claim to have "invented" the 
kerfing plane.
(Here's some more information on Blackburn's website, including instructions
for making a version of this with an adjustable fence, as well as pointers
to a patent from 1866.)

Anyway, along these lines I have what is essentially a metal version 
of one of these
that I picked up in a junk-box at an auction.

Basically someone had a badly damaged main-body of a 55.(for example 
the screw-adjuster
was broke off, among other things).   So they attached a saw blade to 
the bottom.
Works just fine as a "stair saw".

But more to the point, enough of the original body is still working that
I could attach the fence off my 45, and use it as a "fenced" version.

N