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US Patent: 20,192
Method of seating the movable cutter in expansive bits
Patentee:
William A. Clark (exact or similar names) - Bethany, CT

USPTO Classifications:
408/194, 408/195, 408/212, 408/213, D15/139

Tool Categories:
woodworking tools : hand drills : drill bits : adjustable drill bits

Assignees:
None

Manufacturer:
Connecticut Valley Mfg. Co. - Centerbrook, CT
R. H. Brown & Co. - New Haven, CT
W. A. Clark & Co. - Westville, CT

Witnesses:
Thomas P. How
Penelope S. Baine

Patent Dates:
Granted: May 11, 1858

Reissue Information:
Reissued as RE3,516 (Jun. 22, 1869)

Patent Pictures: [ 1 | 2 | 3 ]
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Catalog of the Connecticut Valley Mfg. Co.
Vintage Machinery entry for R. H. Brown & Co.
Description:
The invention is an expansion auger bit where the movable cutter is held in place by a beveled key. The patent was extended and was manufactured for about a century, being widely copied once the extended patent expired in 1879. The expansion bits were manufactured by the inventor's son, Frank Emerson Clark, as W. A. Clark & Company. Frank became a partner in R. H. Brown & Co., and by 1903 that firm was the stated successor to W. A. Clark & Co. and was making this patent expansion bit, marked as "Brown-Clark". The bits were also made by Connecticut Valley Mfg. Co., a.k.a. Convalco, and we have seen such bits marked with the patent date which implies that they were licensed during the term of the patent. This style of expansion bit was made as late as the 1950s by Robert H. Clark Co., of Beverly Hills, CA; since the patent was long expired by then we do not list them as a manufacturer on the patent.

A correspondent reports an example, with "Wm A Clark—Cast Steel Pat May 11 1858 Pat Ext'd" stamped on it. Another example was made by Connecticut Valley Mfg. Company, Centerbrook, Connecticut.

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