Not all slide rules are formidable wood and plastic monsters. Some of the most useful and commonly used rules are inexpensive cardboard or thin plastic "purpose built" devices. One of the original, and largest makers of these specialized rules was Perrygraf, originally based in Maywood, Illinois. They were very ingenious at adapting basic slide rule concepts into product selectors, parameter analyzers, and dedicated calculators of all kinds. Perrygraf was sold in 1968 to Nashua Corporation, which moved the company operations to Los Angles, California, and to Puerto Rico. James E. Johnson, formerly of Perrygraf, didn't want to move in the new re-organization, and continued to make and design slide charts in his home. He also eventually took on the private customers of Perrygraf founder Oscar Perry after he passed away, and founded American Slide Chart in 1970. American Slide Chart was very successful, and eventually took over former competitor Perrygraf itself in 1988, making it the largest producer of this type of slide rule product, as well as pop-up 3D calendars. Founder James E. Johnson died in 1988 and the business is now run by his three sons, James D., David and Craig Johnson. Perrygraf and American Slide Chart ran and operated as individual companies, and often competed for the same customers, but ar enow one entity. Datalizer is another major slide chart/wheel chart player, also in Illinois (Addison), the state that seems to be the birthplace of most US activity in this area. Datalizer offers a unique capability in the form of a wide range of very useful commonly requested stock designs which can be bought in small quantity (as low as 100 pieces non-imprinted), either printed or non-imprinted with your company information.
Datalizer Stock Examples
Some of these rules started out being fairly primitive, but many are very sophisticated such as the Planisphere above, and extremely useful for specific problem solving. The electronics industry has been a big user of these devices as product promotions and component specifier guides. The examples shown at the bottom of the page are mainly from my own personal collection over the years, and give a good idea of what is possible with this technology. These devices are still made today, and are one of the very few slide rules still in production. Where applicable, both side of the rule are shown. Clicking on the THUMBNAIL will bring up a larger view.
Notes: Sizes are given as the over-all size of the rule itself. CAUTION, the images while compressed JPEGs, are large in size to show the rule details, and may be slow loading from remote sites.
YOU CAN STILL GET THESE! This type of rule, often called a "Slide Chart" (or Wheel Chart if it's circular), is still manufactured in large volume, and here's where to go and get them. Thanks to Craig Kielhofer and his excellent detective work, we can now give you this contact information on current manufacturers. They even have WEB SITES! just click on the company name below to go there.