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Description: |
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This is the first of two patents issued to Mathew Biersdorf
for a butt gage suitable for marking both hinge and lock
mortises. His 1918 patent (1,282,670) was a simplification
of this design, and was produced commercially, but the
production tools were marked with this patent date as well.
The main new feature of this tool is the split marking arm,
which allows the tool to mark either one line (for hinges) or
two lines (for the lock mortise), each accounting for the
gain needed for door layout.
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