For around-the-house use, a combo sq. with a zinc physique is the best choice. It’s dependable and straightforward to calibrate, and if the ruler bends, changing it doesn’t break the financial institution. As Invoice Hylton writes at Rockler.com, the web site of a well-liked woodworking retailer, this stage of combo sq. constitutes the low finish of the class: “Extensively utilized by development staff, tradespeople and DIYers, these are sensible instruments, subjected to job website circumstances, designed for development calls for.” In distinction, high-end fashions just like the Starrett have forged iron our bodies and tempered-steel rulers, however their price is extreme for dwelling use. Subsequent to these top-notch squares, Hylton says, with the zinc mixture squares the “accuracy could also be iffy and their scales a skosh coarse, however they work nicely.” Hylton seems to be talking from the attitude of an completed woodworker, for whom the measurement tolerances are extraordinarily excessive. I’ve performed loads of high-end end carpentry work with a zinc combo sq., and as soon as correctly calibrated, they’re undoubtedly correct sufficient for common use.