Sterling Tool Works Double Square is a precision square supplied with one traditional graduated rule and a dovetailing rule providing a very versatile tool with many uses. The standard rule provides a wonderful compact square with excellent accuracy rivaling common machinist square accuracies of .001” per inch, per U.S. federal standard: GGG-S-656E. Available with either a 4" or 6" precision etched rule with chrome satin finish with blackened etches that is easy on your eyes for excellent contrast and improved accuracy.
The included Sterling “Dovetailing Rule” is incredibly handy for checking the squareness of your dovetails to ensure excellent fit and “gap less” joints after assembly. The reduced size of one end of the un-graduated rule allows precise checking of squareness in even some of the tightest “London style” dovetails. Regular size rules simply cannot reach into the spaces the Sterling Dovetailing Rule can. The Dovetailing Rule is hardened, precision ground and finished with the same satin Chrome finish as the standard rule. The standard precision etched rule is 4” inches with English/Metric graduations = .5mm, 1mm, 32nds, 64ths
The powder coated square casting provides the accuracy required but avoids the stock-heavy feel of a solid machinist's square, providing excellent balance and feel. Rules lock securely in any position from full left to full right with the tightening of the knurled thumbscrew.