Setting blade tension and tracking.

Tension and tracking decide whether a bandsaw cuts straight or wanders, and whether its blade lasts or breaks early. Tension is how tightly the blade is stretched between the wheels. Tracking is where the blade runs across the width of the wheels. Both are set with the upper wheel, and both come before the guides. Your manual’s method and settings come first; this page explains what they are for and how to check them.

Tension.

Most saws have a tension knob or lever that raises the upper wheel, and many have a scale marked with blade widths. Wider blades need more tension than narrow ones. Start with the setting your manual gives for your blade’s width.

Treat the built-in scale as a guide rather than a measurement: it reads the compression of a spring, which changes with age and differs between saws. Woodworkers commonly check the tension in two further ways:

• The sideways push. With the saw unplugged and the upper guide raised, press the blade sideways with a finger halfway between the table and the upper guide. A properly tensioned blade moves only a little and springs straight back; a slack one moves easily.
• The flutter test. Some woodworkers lower the tension with the saw running until the blade starts to flutter, then raise it until the flutter stops and add a little more. Only do this if your manual allows tension changes while the saw runs, and keep your hands well clear of the blade.

Signs of too little tension: the cut wanders, bows in deep stock, or the blade slips on the wheels. Signs of too much: blades crack early and the wheel bearings and tension spring wear faster. Some manufacturers recommend releasing the tension when the saw won’t be used for a while, which also takes the load off the tyres; check your manual.

Tracking.

1. Back the guides off. Move the upper and lower guides and thrust bearings away from the blade so they don’t influence it.
2. Tension the blade to your setting first; changing tension later changes the tracking.
3. Turn the upper wheel by hand and watch where the blade settles on the tyre.
4. Adjust the tilt. Turn the tracking knob, which tilts the upper wheel, a little at a time until the blade runs where your manual says: often near the centre of a crowned tyre, but some manuals give another position for wide blades.
5. Close the covers and check. Run the saw briefly, switch off, and check that the blade stayed in place.
6. Set the guides back to the clearances in your manual. Guide blocks or bearings should sit just clear of the blade and behind the gullets so they never touch the teeth; the thrust bearing should only turn when you cut.

If the blade won’t stay put however you adjust it, look at the tyres (see bandsaw tyres), then the blade itself: a blade with a bad weld or a kink never tracks well.