In 1908-9, John H. Dorman, who had been a machinist for a typewriter manufacturer, patented a reversing tapping head for a drill press and by September 1908 he was manufacturing them in New York City under his own name. He manufactured them in three sizes and subsequently he introduced a series of multi-spindle tappers. and then a series of multi-spindle combined drilling and tapping heads. By 1919 son Edward A. Dorman had joined the business which operated as John H. Dorman & Son. In 1921 Edward patented an automobile jack which they also manufactured.

From 1920-06-24 American Machinist

Strangely, the two men and their products seemed to disappear from the early 1920s onward. In about 1947 the Dorman lineup of tapping and drilling heads were being produced by Dorman Machine Tool Works, headed by Walter E. Dorman. In 1948 Walter was granted a patent for an improved method for attaching chucks and heads to spindles. Then in 1949 the Dorman Machine Tool Works merged with Thriftmaster Products Corp., continuing under the Thriftmaster name although the Dorman name was used by Thriftmaster on the drilling/tapping heads and Walter was their general sales manager.

Information Sources

• September 1908 Machinery.

  John H. Dorman, 1 Bethune St., New York City. Tapping attachment for use in sensitive drill presses. It will drive taps up to and including 3/8 inch in diameter. A stop is provided which, when the desired depth of tapping has been reached, reverses the spindle and backs the tap out. A friction device has been incorporated into the attachment.

• July 1910 Industrial Engineering.

  Tapping attachment for drill press.—John H. Dorman, 1 Bethune St., New York. An effective and durably built device handling all sizes of taps up to 1 in. in its three sizes.

• April 1919 Machinery.

  Tapping Attachment: John H. Dorman & Son, 1-9 Bethune St., New York City. A list of multiple-spindle tapping attachments which are made with various numbers of spindles to meet the requirements of special cases. The attachments are provided with a tapered shank, by means of which they may be mounted in an ordinary drilling machine. The case is made of aluminum to reduce weight, and the spindles are gear driven.

• 1923-02-28 American Machinist has an article on the Dorman Multiple-Spindle Drilling Head being produced by John H. Dorman, 5148-5152 Hudson Boulevard West, West New York, N. J.
• 1946 Industrial Directory of New York State, page 459. "Dorman Machine Tool Works, 357 Canal St., NYC, NY—Machine Tools"
• 1949 Machinery (p. 228).

  Dorman Machine Tool Works, Mount Vernon, N. Y., and Thriftmaster Products Corporation, Lancaster, Pa., have consolidated their manufacturing and sales activities. Hereafter the complete lines of Dorman tapping attachments and Thriftmaster adjustable- and fixed-center drill heads will be manufactured at the Thriftmaster plant, 1034 N. Plum St., Lancaster, Pennsylvania. Walter E. Dorman, partner in the Dorman Machine Tool Works, has been appointed general sales manager of the Thriftmaster Products Corporation.

• 1949 Modern Machine Shop (vol. 22 p. 190).

  The complete lines of Dorman tapping attachments and Thriftmaster adjustable and fixed center drill heads will be manufactured at the Thriftmaster plant, 1034 N. Plum St., Lancaster, Pennsylvania. Walter E. Dorman, partner in the Dorman Machine Tool Works, has been appointed general sales manager of the Thriftmaster Products Corporation.