This one is SIMPLE! But don't underestimate it. I've seen a lot of people damage shears by cutting sandpaper with them.
Materials you need:
- Straight edge
- Scribe (this one is carbide)
I did this at TechShop Detroit: "Build Your Dreams Here"! Using your tools safely and to their best advantage!
Step 1: What To Do
Step one: TURN YOUR PAPER OVER so the gritty side is facing down. Mark any size and shape you need on this smooth paper side.
Step two: Use your scribe along a straight edge (or maybe a template if you want to make curves or complex shapes) and SCORE the paper. Don't try to go through, we don't want to dull the scribe with grit.
ta-dah! You'll see that the paper weakens so it will tear with a very clean edge.
Step 2: What Not to Do
PLEASE don't use edged or shearing cutting tools. Sandpaper is meant to WEAR AWAY METAL. Why dull and ruin your tools?
Don't use knives, scissors, or shears.
Step 3: In A Pinch
If you need "just a strip" or you're not concerned about a clean, clean edge, fold and crease your sandpaper very well, with the paper back to the outside. This will tear nicely, though be prepared for uneven creasing or feathered edges, especially with coarser grits.