There are three main reasons for this happening:

1. The blade itself has lost its set on the teeth. By replacing the blade with a good quality blade this problem will be overcome. Losing the set off a blade unfortunately is common when cutting re-claimed timber and the only way to remedy the problem is to replace the blade.

2. The blade is worn and no longer sharp, again by replacing the blade with a good quality blade this problem will be overcome.

3. If the blade however is in perfect condition then the most probable cause is that the blade is undertensioned.