PB Cohen Creations

The width of a saw cut is called a kerf. The smaller the blade, the thinner the kerf. You can see the difference in the photo below (click on the photo for a bigger version):

In the top strip, the line between triangles on the left (making "arrows") was made with a size 2/0 saw blade; the line between the triangles on the right was made with a size 5 saw blade. In the bottom strip, both lines have been finished with the size 5 saw blade. You can see how the kerf from the bigger blade becomes a design element — that thicker line is more visually interesting than the thin line. On a practical level, since I was sweat-soldering this strip onto another piece of metal, the thicker line would be much less likely to wick up solder, and get filled in.

It would be possible to make a cut with a thin blade, and then enlarge it with sandpaper carefully fit into the slit — but it would be slow, and the less straight the cut, the more difficult that method would be. However, cutting relatively thin sheet metal with a relatively thick saw blade is also pretty tough. It was a little easier to use an intermediate size blade before jumping to the biggest one (that is, use a 2/0, then a 2, then a size 5). But what made it easier for me was to cut into the bench pin, and cut through the metal as a side-effect. Those big blades are just annoying to use on thin sheet metal!