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With this device, one could bore holes into framing members
without having to squeeze into the joist box or stud cavity.
In practice, it is used by placing the 22-1/4" long section
against the framing. That long section allowed for spanning
the spacing of joists and studs. The height for the hole in
the opening was adjusted (up to 7-1/2" away from the
face, 15" deep opening) and the moveable handle was rotated
to advance the auger bit while minimal feed pressure was applied
with the other handle. The feed pressure needed was far less
after the invention of the lead screw. Without that innovation,
this tool configuration would not have worked with any reliability.
Earlier
center bit (pre 1850) designs required considerable force
to advance the bit; it would be difficult to apply this force
while drilling in an opening at right angles and rotating
a handle.
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Mechanism and bit. |
Various
sizes of square-tang bits can be accommodated in the chuck,
but in practice, nothing larger than 1" was needed for
wiring purposes. There would have been no need for this brace
prior to 1880; in the subsequent years, to 1920 and later,
numerous other types and variations of this brace were put
forth as solutions until development of the electric drill
displaced it.
Electricians (a term not used before 1900, as the trade did
not exist then) felt that this tool was made just for them;
their opinion was that plumbers would just cut out the offending
structural member.
D.S. Orr
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