An Engineer‘s Tee-square

摘要

This tee-square was made to complement my spring parallels [MEW223) which were designed to facilitate the setting up of workpieces in the machine vice. The spring parallels are simple and effective, but since they do not show when the desired setup has been achieved, separate tests must be carried out as part of the adjustment process. While it is possible to obtain good results by using a surface gauge or sticky pin to pick up a line scribed horizontally across the job, a positive mechanical indication is to be preferred, and this means setting the side of the job vertical. Almost immediately, however, a snag is encountered, for it is found that the most obvious tool for the task - the engineer's try-square - cannot be used, owing to a lack of space. Meeting with this very difficulty 30 or more years ago, George Thomas conceived the idea of making his own special tee-square, the blade of which was mounted on, rather than in, the stock, so that when the stock, which was narrow, rested upon the top edge of the fixed jaw-plate, the blade passed down between the jaws and could be brought into contact with the side of the job.