The Modified Square isn’t an easy tool to wrap your head around — I’m still trying to completely understand it myself. At first glance it looks like a framing square that got into a bad accident, but upon closer inspection there are some intriguing uses for it, like transferring measurements from the underside of a workpiece to the top and finding the quarter points on round stock.
The Modified Square is similar to a framing square in that it’s a powder-coated steel rule with a primary blade and tongue set at 90° to each other, but after three inches the primary tongue takes a right-hand turn to form the secondary blade, and then the secondary blade takes a left turn after another four inches to create a tool that looks somewhat like a lopsided question mark.
Every edge is covered with graduated markings in 1/8″ increments. The primary blade is marked in a scale from 0 to 12-1/2″ on one edge, and it features a centering scale on the inside edges where the center corresponds to the inside edge of the secondary tongue. The markings on the secondary blade continue 90° around the secondary tongue.
There are a ton of uses for the Modified Square like marking notches for 2x4s and marking notches for stairs on stringers, but just listing them doesn’t do the tool justice. That’s why I’d refer you to the Corporate Site to see their demonstration pictures, rather than trying to explain them all.
You can purchase the Modified Square from the corporate site, some local retail locations listed on the corporate site, or at Woodcraft for $25.