Popular Woodworking 2000-06 № 115, страница 14
Choosing the 'Right' Triangle For the Job For benchwork, we can mark things at 90 degrees with various squares, but if we get outdoors to lay out the foundations of a workshop, the base for a playhouse, or just a plot of land, squareness becomes a different problem. The corner of a 4 x 8 sheet of plywood is usually square and used to mark anything within its range, but many outdoor projects are bigger than that, and the best method to use to get a large square corner is the 3:4:5 technique. In a triangle with the sides in the proportion 3:4:5, the angle between the two short sides is 90 degrees. So, 1) Choose units in which one short side, usually the "3," is longer than the finished length you want. As an example, choose five feet. Stretch a baseline string 20 feet (four "units") between pegs or nails. 2) From the corner point of the triangle, stretch your tape measure 15 feet (three units). 3) From the other point measure 25 feet (five units) with another tape measure. 4) If you don't have two tape measures handy, a five unit (25') and a three unit (15') string starting from the A and B corners will meet on a direct line to the A corner point, which will be square to the baseline. You can then measure other positions from these square lines. Percy W. Blandford Stratford-on-Avon, England A Piece of Tape Makes your Miter Gauge More Accurate Attach a 3/4" x 21/2" x 28" board to your miter gauge (not an original idea), then put a piece of masking tape on the table saw in front of the blade insert. Then cut partway into a board using the miter hold down. Shut the saw off and slowly pull the board back until the board is half covering the tape. Mark a thin line on the tape to indicate both sides of the kerf. Now when you want to make an accurate cut, line up the mark on the workpiece with the mark on the tape. Change the tape when you change blades. PW Bernard H. Derbyshire Newtown, Connecticut |
