If angle-cut work pieces don't fit together, you may need to adjust blade alignment, the bevel positive stops or the bevel pointer. If the angle cuts have ragged, torn, splintered or burnt edges, you may need to replace the saw blade.
The blade must be parallel to the miter gauge groove to achieve clean angle cuts. Check blade alignment using a combination square and adjust the blade to parallel with the miter gauge groove if blade alignment is off.
Next, check the 90-degree and 45-degree bevel positive stops and adjust those stops if necessary so blade angle is accurate.
Check the accuracy of the bevel pointer and adjust the pointer to accurate indicate blade angle.
The saw blade must be clean and sharp to make clean angle cuts. Check the condition of the saw blade for damage or residue. Clean gum or pitch residue off the blade using turpentine and steel wool. Replace the blade if it's worn or damaged.
