| Dovetailed Steel construction
versus a Bronze casting The earliest metal planes were made by dovetailing
wrought iron plates together to form a plane body which was then fitted with wooden
insides. Hence the name "Infill". The metal sole minimized wear and enabled a
very fine mouth, both essential attributes of a fine plane. The wood infill dampened
vibration. Many manufacturers made infill metal planes in a variety of styles from about
the 1840's to the 1940's. Among the largest were Spiers, Mathieson, Slater, Norris, and
Preston  . There were a multitude of other smaller
manufacturers and many retailers who sold planes made by others under their name. Norris,
like most of the larger makers, sold plane parts to whomever wanted to buy them including
individual craftsman. With very few exception infill tools are an English phenomenon and
were not made on the Continent or in the United States .
There are two basic ways of making an infill plane. The body must either be dovetailed
together from steel plates or formed from a casting. In the former method three steel
plates are joined by cutting dovetails and then forging the sides and sole together. This
produces a carcass that won't warp from casting stress, but it requires a tremendous
amount of skilled labor. The other way is to cast the body out of either malleable iron or
bronze. This simplifies the situation but casting will have a tendency to warp, so care
has to be taken. Gunmetal bronze wears, so it was usual in the better planes to solder a
steel sole onto the body to give a hard wearing surface to the sole. This also meant that
it was stronger and it was easier to make a fine mouth. In both cases the finished body is
then stuffed with hardwood, usually rosewood, but ebony and other dark tropical woods were
used.
Aside from the obvious differences of construction between infill shoulder planes and
the Preston cast iron design, a major difference is that on Norrises any space under the
blade that is not part of the body casting is filled with wood (beech). On Preston
shoulder planes this space is empty. |
| The fine mouth
A fine mouth is essential for a great trimming plane. In a shoulder plane, with the
blade bevel up, the mouth only has to be wide enough for a tiny bit of blade to stick out
and for thin shavings to pass. The extra bit of plane bed supporting the blade as close to
the cutting edge as possible reduces vibration, and the fine mouth keeps a newly formed
shaving of wood from splitting ahead of the blade. The former feature helps keep a
consistent cut which improves the final surface and the latter feature reduces tearout.
Flatness of the sole
A second major factor is the flatness of the sole. Dovetailed steel planes in good
condition are very flat, any concavity being formed by either extensive wear or misuse.
However, it is routine to find steel soled bronze planes with a slight concavity of the
sole. It is not known whether the concavity is the result of stress released in the steel
bronze body over a long time or whether the tools warped shortly after leaving the
factory.
Proper fitting of the wedge
A wedge that truly locks the blade in place all along the body of the plane, especially
near the mouth, is carefully fitted. A properly fitted blade will be only slightly wider
(.01") than the shoulder plane body. With one exception the infill shoulder planes
were not made with adjusters but as most planes of the time didn't have adjusters, this
wasn't at all unusual or a great problem for the user. |
. Today the names are routinely misused interchangeably but the planes
styles are distinct in function and appearance. The shoulder plane is so named
because it has a primary use in fine turning the shoulders on tenons for a better fit.
However, it is fabulously useful in helping tune almost any inside corner condition. To do
this it must be a precision tool, and it is. The typical shape of a shoulder plane gives
nice grips for holding on the plane as it carefully balances on a tenon as it shaves away.
A bullnose plane, the stubby son of a shoulder plane, is also a precision tool that
excels at trimming operations. However, its short nose and small size allows one handed
operation in small spaces where a shoulder plane won't fit. The rabbet plane, which
is usually of a rectangular shape, is designed in two flavors. A rough plane with a
largish mouth for wasting away wood so it can efficiently cut a rabbet in the side of a
board. Some rabbet planes had spurs for cutting across grain without tearing. A more
precise version of the rabbet plane also existed for finishing up the rabbet. This latter
version had blades that were typically bedded at a higher angle so the plane would work
better across the grain. Most firms made both rabbet and shoulder planes,
however this exhibit focuses on shoulder planes which are still some of the most useful
planes to have in a modern workshop. 
