Cutting, Not Hacking
Marking and guiding moves that put the cut where you meant it, on pipe, tube, trim and paper.
Metal & Pipe
3 rulesCircle center + 12 points
Set the heel of a framing square on the circle and mark where both blades cross it; those two points are the ends of a diameter. Draw two diameters and they cross at the center. Then step the radius off as a straight chord from each of the four quarter points to get 12 points at 30°.
Mark an angle on a pipe
Turn the angle into a distance around the pipe: arc length = outside diameter × π × degrees ÷ 360. Mark that distance on a thin paper strip, wrap the strip around the pipe from a 0° reference line, and transfer the mark. On a 2 in (50.8 mm) OD pipe, 25° is 0.436 in (11.1 mm).
Speed square Portaband guide
Clamp a speed square across the tube as a fence, set back from your cut line by the distance from the blade to the edge of the saw's shoe, on the keep side. Run the shoe along the square the whole cut and the blade tracks your line square instead of wandering.
Guides, Gauges & Templates
3 rules
Ido AgassiMagnetic ruler hold-down
Put a magnetic knife bar flat under the cutting mat along the cut line, shim the rest of the mat level with cardboard, and lay a steel ruler on the mat over the magnet. The magnet pins the ruler along its whole length, so it holds paper or one sheet of board without you leaning on it.
Pocket door jamb gauge
Glue two strips of scrap together with an offset to make a stepped gauge block. Hook the block on the pocket-door frame, push each split jamb against the step, and fasten it there at several heights. Every jamb lands the same distance from the frame, so the gap stays even top to bottom.
Scan to trace a part
Lay the part flat on a flatbed scanner next to a sheet of paper of known size, import the scan into CAD, scale it off the paper's long edge, and trace the part over it. Anything touching the glass scans at true scale, with none of a phone lens's distortion, so outlines and holes come through right.