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You've probably heard the clich about building your house on a solid foundation. In machining, square blocks are the foundation of many machined parts. As a machinist, you need to know how to construct precisely square blocks and how to check them. It's nearly impossible to hold tight tolerances on subsequent machining operations if your blocks are not square.
Like many things in machining, there are a variety of methods one can use to construct square blocks.
You may think, "What's the big deal? every machinist knows how to make square blocks." There's likely more to it than you think.
Use a modified ball bearing to hold rough sawed stock in your milling machine vise. (See Fig. 12-2)
Figure 12-1: Square blocks are the foundation of many machined parts
Figure 12-2: A modified ball bearing is used to apply pressure to the center of rough sawed stock
A steel ball with a flat can be used to apply pressure to the center of the vise and the center of rough sawed stock. The ball should be used when there are no parallel surfaces on the stock for the vise to close on. You may have to use the ball a few times to get some surfaces roughly square and parallel before you begin the precision squaring process as described in the following paragraphs. The flat on the ball allows the vise to be closed tightly without damaging or indenting the vise jaw. The ball should be large enough so that...
