It is amazing to think about all the groundbreaking devices that were invented in this area over the years. Starting with Robbins and Lawrence in Windsor, in the mid 1800’s, with what came to be known as the “American System”. Looking at it now, it was quite a simple idea: make each part of a machine interchangeable, so that assembly of that machine could be quick and economical. But in the beginning the basic problem was to be able to make parts to close tolerances. The early machining processes did not lend themselves well to this, as the machinery was quite crude. With the building of better, more accurate, machinery, the idea became fact. It started in Windsor, with the manufacture of rifles for the Civil War. When I talk here of “machines”, I mean anything from guns to lathes to automobiles. Once the parts were made “identical”, mass production could be achieved. Much quicker and cheaper, than hand building each gun, lathe, or whatever.

James Hartness had developed a line of threading dies in the early 1900’s, but recognized that the inspection procedures of the time were crude and time consuming. At the time he was the chairman of the National Screw Thread Committee, and his interest in optics (he was an amateur astronomer), gave him an idea. With the help of Russell Porter, a Springfield native who was also familiar with astronomy, they developed the optical comparator around 1920. Using a set of magnifying lenses, and projecting a high powered light beam over the threads, and matching the profile onto a drawn chart, it was possible to measure, within very close tolerances, any feature of the thread, pitch, lead, root radius, etc. The lenses themselves were magnifying type, I.E. they magnified the profile so it was easier to measure on the charts. The optical comparator became a good fit with the other machinery that J&L sold.

The heart of the comparator is the lens system. There were no commercially available lenses that could be bought at the time, so J&L set about to make their own. They set up a lens grinding room and proceeded to grind their own lenses and mirrors to very precise and polished tolerances. The company offered lenses in several magnifications, depending on the job at hand. The basic comparator had a 14″ diameter screen, but sizes up to 30″ were available for larger workpiece inspection.

Because of the success of the TNC lathe product line, and the expected expansion of models, J&L had a serious lack-of-room situation. So a management decision was made to move the comparator product line out of Springfield. Textron had an empty factory building in South Carolina that had been used by Talon Zipper. This happened around 1980 or so. Anyone who was a part of the product line, engineering, sales or assembly, was offered a job in the new facility. Some decided to stay in Springfield, and some in Plant #1 wanted to move south. So there was some “swapping around” to accommodate these people.