Making a Wooden Smooth Plane, Part 2: Abutments and Throat Shaping

In the previous post, I finished the primary excavation.  That left me with a flat bed, though it was narrower than it needed to be.  I needed to extend the bed to the full width of the iron, plus 1/16", and this would create the abutments and form the recesses for the iron and wedge.  Here's how it was done.

Used a flush-cut saw down to the 1/4" line, referencing off the bed ...

... but used a 0.019" thick cereal box shim to ensure not going below the bed line

For the final plane, I used a 0.010" thick brass shim

Can't see them here, but I also marked 1/4" depth lines on the saw blade so that I wouldn't saw too deep

For the cut that defines the front aspect of the abutment recess, I made a temporary sawing guide at the combined angle of the iron and wedge and screwed it to the bed.  I was able to use the layout lines on the plane body to figure out the angle.

The temporary sawing guide screwed to the bed

In this close-up, you can see I positioned the guide so that the thickness of the saw will get me to the cut line

Then I sawed to 1/4" depth ...

... and I'm left with the abutment recess delineated

Then some careful paring gets the side walls down to the sawn lines

You can see that my shims left me some material to pare away.  But the nice, flat bed gave a good surface to reference a chisel against to pare that down even with the bed.  That was the reason, BTW, that I used the thinner shim on the final plane - paring the leftover bit on the prototype from using the 0.019" thick shim was harder than it needed to be.

Here's the completed abutment recess on the final plane.
The slot for the cap-iron screw has also been drilled and chiseled out.

The next step in shaping the throat was to widen the front aspect.  I showed the following sketch a couple weeks ago when posting about throat geometry.  The throat is widened by cutting down from "1" to "3", with the saw angled to cut 1/4" deep at "1" and not at all at "3".

Throat widened at front

Cutting at an angle - you can see the teeth down deep are not engaged in wood

Then it's a matter of paring away the waste to get a smooth side wall, angled at top.  Finally, I marked and cut to lines for the "eyes", the softened edges that spare tender fingers when clearing the throat of shavings.

"Eyes" laid out

On the prototype, I pared about the same amount on top as on sidewall (basically 45° paring).
That was a mistake that I corrected on the final plane, cutting more on the sidewall than on the top.

I'll continue next time with the wedge, first cuts and final shaping.