Patented & Distinctive Bit Braces, a Research Study
by
George Langford, Sc.D.
Updated January 22, 2006
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Ives - Pfleghar patent bit brace. Here's a brace that has two clearly defined and almost literally followed patents, separated by more than eight years, making the active period of patent protection less than nine years.  The Pfleghar patent is the earlier one and also the most difficult to recognize, because the rotatable pawl is disk-shaped in the realized version and just a segment of a circle in the patent drawing.  The Ives-patent chuck is shown exactly as made in the patent drawings.

The chuck's parts, save the shell, are a mixture of cast iron and steel.  The quality of the cast iron is somewhat suspect, as the threads of the cast body have partially fractured from the strain of tightening the sleeve of the chuck onto bits, as seen at lower right, above.  This is a frictionally challenged design, clearly an attempt to modernize the Spofford patent, where a transverse screw was used to effect the same elastic closure of fixed portions of the frame as seen here.  This is a quite well made brace nevertheless.