Believe it or not, it’s the nature of a bandsaw. There are several possibilities would result in bandsaw not cutting straight.
- BLADE IS DULL
A dull blade will twist when cutting the work piece and cut the piece crookedly. You'll also need to push the work piece harder to move it through the cutting area when the blade is dull.
- BLADE IS INSTALLED INCORRECTLY
For most blades it is obvious if the blade teeth are pointing the correct direction. On a typical wood cutting blade the hook or of point of the blade should be pointing down. This forces the workpiece down into the table. Otherwise, the blade is trying to lift the workpiece up from the table. Typical bandsaw blades can be flipped “inside out” to make the teeth point the other direction.
- INCORRECT BLADE TENSION
Loose blade tension can cause the blade to twist and veer off course when cutting the work piece. Check blade tension by pressing in on the side of the blade using a gloved finger. Tighten blade tension if you can easily push the blade in more than a 1/4-inch.
- BANDSAW WHEELS ALIGNED INCORRECTLY OR WORN
The blade should run at or near the center of the crown and not excessively close to the front or rear edge of the wheel. Being ⅛ or ever ¼ inch from the exact center of the wheel is generally not a problem. Before making any adjustments to the blade wheels check the adjustment of the blade guides. Improperly aligned guides can cause the blade to track improperly on the wheels.
- BANDSAW BLADE GUIDES ARE MISALIGNED
Typical bandsaw blade guides have 3 elements, one on each side of the blade and one to the rear of the blade. For the side guides the ideal is a close but free running fit, about the thickness of a dollar bill. The rear guide should be ⅛to ¼ inch clear of the back of the blade. If push harder then the blade may start to twist or buckle, it will hit the side guides. The side guides will assist in keeping the blade cutting straight, but they are not an iron lock on the blade forcing it to cut straight.
- IMPROPER FEEDING
Using too much force when feeding the work piece through the cutting area can cause the band saw blade to twist and cut the piece crookedly. Use light pressure when feeding the work piece through the cutting area to achieve a straight cut.