The patented Spindle Square was developed and patented by Joseph Navarro, an American machinist and tool and die maker, as a response to the demands in his own production machine shop for a more efficient and economical method of squaring the head on the manual milling machine.

It was customary to run over 1000 jobs a year through his shop. The head of the mill had to be squared prior to running each job to ensure accuracy. The lack of trained toolmakers made the task of keeping up with production difficult as apprentices could not tram the head of the mills--only the advanced toolmakers could do it.

So, he consolidated the knowledge of the standard indicator tramming method into the instrument and developed the Spindle Square, initially to make his job easier in tramming the mills.

However, his lead toolmaker noticed the instrument and began using it--and loved it! He wouldn't tram the mill without the Spindle Square. It's ease of use and ability to achieve .001 accuracy quickly, efficiently and without hassle made it a favorite. Soon, everyone in the shop was using it and now thousands of machinists throughout the US and the world are using it.