In business by late 1941, the Jefferson Machine Tool Co. of Cincinnati was a small, little-known firm that made the "Bulldog" small horizontal milling machine, a swing-frame grinder, machine vises, and a woodworking belt sander.

We have seen a milling machine identical to the Jefferson Bulldog but with the A. V. Carroll name on it. That firm is older than Jefferson Machine Tool so it seems most likely that the Bulldog milling machine originated with A. V. Carroll Machine Tool Co., and when that firm was dissolved the product went to Jefferson Machine Tool. We have been unable to find any confirmation of this hypothesis.

Information Sources

• November 1941 The Tool Engineer, page 116: brief illustrated article on the Jefferson Swing Frame Grinder from Jefferson Machine Tool Co., at Fourth, Cutter and Sweeney Streets, Cincinnati, Ohio.
• December 1941 The Tool Engineer, page 110: brief illustrated article on the Jefferson milling machine, of "Bull-Dog" design.
• From a 1942 issue of School Shop.

  Of particular interest to shop teachers will be the milling machine and the conversion attachments for making and engine lathe into a turret lathe. Copies of the booklet may be had without charge from the Jefferson Machine Tool Co., Fourth and Cutter Sts., Cincinnati, Ohio, or from School Shop.

• The 1966 MacRae's Blue Book lists Jefferson Machine Cool Co., 671 W. 4th St., Cincinnati 3, O. (Tail Stock Turrets for Lathes).
• Article in a 1976 isue of American Machinist on this firm's No. 101 swing grinder, which used 14" wheels.
• A 2019 eBay listing for various Jefferson Machine Tool Co. bulletins, including the Bulldog high speed precision milling machine.