Clean Miter Saw Crosscuts

Any type of crosscutting tends to leave splintered ends on lumber, because the wood fibers run lengthwise in the board. Ideally, the metal edge of the blade should be sharp enough and spinning fast enough to sever the fibers before the blunt force breaks them off. This is easier to accomplish on the “front” of the board, where the saw teeth enter the surface and push the surface fibers into the wood. On the “back” face, where the saw teeth exit the wood surface, there’s little to support the wood fibers, so most of the tearout occurs there.

The simplest remedy with a miter saw involves using a sharp crosscut blade (with 60 or more carbide-tipped teeth) and keeping a board’s “good” face (the one that will show when the project is completed) oriented up so the blade enters on that surface. This doesn’t address tearout on the back side where the blade exits, but often that will not be visible after assembly. And normally those small imperfections will not affect the strength of the joinery.

If not getting clean end cuts still bothers you or presents aesthetic problems for a particular project, there are other options. For occasional cuts, you can apply masking tape to the cut line (front and back sides), which will help keep surface fibers from tearing before they are severed cleanly by the blade. This is a time-consuming solution, though, so it’s not practical for frequent cutting.

The real trick lies in making sure the surfaces of the board are supported right at the cut line, especially on the back face. See if your saw base has adjustable plastic inserts that form the slot where the blade enters the turntable. Most miter saws have these, and you can adjust them so the gap is narrower than the blade kerf; then make a test cut without any boards to let the blade cut its own precise slot. This creates what’s called a “zero clearance” fit, and it will help reduce tearout by providing that critical support right at the cut line. Finally, you can simply use a sacrificial backer board behind your workpiece; press down firmly during the cut so there’s no gap between the stock.