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US Patent: 12,861
Gage for Slitting Lumber
Patentee:
Francis P. Hart - Chandlersville, PA

USPTO Classifications:
33/44

Tool Categories:
layout tools : marking gauges
layout tools : marking gauges : curve marking gauges

Assignees:
None

Manufacturer:
Unknown

Witnesses:
Peter Hart
Harlan C. Richardson

Patent Dates:
Granted: May 15, 1855

Patent Pictures: [ 1 | 2 | 3 ]
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Description:
This patent specifies one of the most complicated marking gages ever invented-- it did just about everything, including some stuff I can't imagine ever wanting to do!

On the plus side, this patent marks the first appearance of the cutting wheel in place of a point or knife edge. The wheel was to become a mainstay in patents from this point forward. Also on this piece was a retractable curved face for marking off concave curved surfaces, as well as a retractable mortise point.

What is most interesting on this piece, though, is that it could be used for marking tapering lines! As the marking wheel turned, it would turn the threaded stem in the head, thus shortening or lengthening the distance between the head and the wheel. To vary the taper, wheels of different radii could be used. A questionable feature at best, but a very cool and gadgety idea nonetheless.

This piece was produced commercially, in two different styles. Neither style is much like the patent, but each embodies one or more of the patented ideas.

The first style is a fairly traditional-looking mortise gage with a rectangular head. Under the arm, however, it has the retractable wheel used for marking off curved surfaces. It also uses the marking wheel as claimed in the patent. These gages are clearly marked with the inventor's name and patent date.

The second style was significantly simpler.

In fact, on the second style the only piece left from the patent specification was the marking wheel, applied on the end of a very normal looking marking gage. I would never even have recognized this as the same patent if it were not marked with the patent date.

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