Workshop Teaser – Truing Roubo’s Square

The upper piece is straight off the table saw, and the lower piece has been prepped with a file and abrasive paper.

Once the main body of the square is cut out and the ends shaped it is time to “true” the outside edges.  There will be several opportunities to fine tune the squareness as we go along, but the first thing is to get those outer edges true.  This provides a couple of functions.  First it establishes the square-ness of the tool overall, and prepares the edge for the soldering of the shoe.

The main tools for this process are a clean, new-ish mill file and a granite block festooned with an abrasive belt.  The objective is to both stablish one surface (the beam) amenable to soldering and one (the bade) that is perfectly square to the first one.  Truing the inside edges comes later.

For this task my reference is one of Chris Vesper’s incomparable squares.  I had let him know what I was needing and he prepared one for me with a run-out of only 0.0002″ over the length of the blade.   If you need something more square than that, you are not a woodworker.  You are a jet engine mechanic.