Mitchells Brace Jaws.

Post date: 28-Jul-2015 06:22:42

Stanley Australia  A144- 10IN Uses Mitchell Jaws.

At a recent meeting one of our members had a query about an interesting pair of jaws in an old brace. The jaws are the type commonly known as "alligator" because of the teeth on their two mating surfaces, but these teeth were in two groups separated in the middle by a short land or toothless section.

This style of jaw was patented by Charles Mitchell, an employee of the Stanley Rule and Level Company of new Britain, Connecticut, USA.

Toothless Plain Jaws.                                                                                                                       Alligator Jaws.

Braces, originally, were designed to grip the square tapered tang of the standard auger bit by various means. as new shapes of tang, round straight, round tapered (Morse) became common, efforts were made to design a jaw that could accommodate them all. In this regard many could be filed in the "Jack of all trades, master of none" department. 

The recognised breakthrough came in 1864 with William Barber of Greenfield Massachusetts patent (42,827) for a brace chuck as we recognise it, with two jaws clamped by a threaded "nut". This was improved upon in 1868 by Charles Amidon ( 73,279) the rights eventually owned by the Millers Falls Company of Millers Falls, Massachusetts, and eventually became the standard, widely used by other manufactures.

Two very similar patentees, John S Fray and Co  of Bridgeport, Connecticut in 1888 (395222)  and Joseph P Bartholomew in 1904 ( 777,657) designed a pair of jaws connected by a U shaped spring running through a hole in the base and running up the back of each jaw. These jaws were available both plain and toothed. Joseph Bartholomew was an employee of the Stanley Rule and Level Company which is where, on December 12th 1911, Charles Mitchell came into the picture. 

In his patent description Mitchell drew attention to the failure and breakage, in the middle section, of current alligator jaws, usually from over tightening, and proposed that his design would result in jaws having more strength in the central area.

Mitchell's  Jaws, US Pat 1,011,227, Dec. 12th 1911.

Mitchell's design called for a raised, toothless section between two sets of teeth to substantially strengthen the central section of the jaw. 

This new style of jaw was used by Stanley, not only in the USA and Canada, but also in England ie No's 73, 75 and 144 and here in Australia, No's A78 and A144. This style, also, has been adopted by manufacturers world wide.

There are a number of different modern jaw types and in the Stanley Catalogue No 34 of 1927 no less than 81 braces are listed and of five jaw types available Mitchell's is used in about 22 of them.

Many hardware merchants offered replacement jaws for braces and for this reason attempting to date a brace from its style of jaw is quite risky.