On a typical wood or metal cutting blade the hook or of point of the blade should be pointing down for a vertical blade bandsaw, or for a horizontal blade saw the hook of the teeth should be pointed such that they enter the workpiece first as the blade moves. During regular cutting on a well set up bandsaw the blade will move or bow backwards a bit as you press the workpiece into it. 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.
This in turn causes the blade to not cut in a straight line. With a dull blade, there is an expectation for it to cut slower and cut crooked. The main thing that normally goes out is the crown, which is what is holding the blade in place, Most of the time the blade is right at the center, but if the crown begins to wear out, it may start allowing more and more movement, causing the blade to not cut in a straight line.
If the blade twists and the work piece is harder to push through the cutting area, replace the blade. Loose blade tension can also 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.
Being a happy bandsaw owner has a lot to do with your approach to coping with the fact that a bandsaw simply will not cut straight, or, in the sage words of veteran woodworkers, “Adjusting for drift.” Even the top performing 14″ bandsaw on the market, Powermatic’s 14 Bandsaw 1791216K, comes with a no-frills fence with 4 bolts on top rather than easy and obvious thumbscrews or knobs that say, “Adjust me here!”. Making the bandsaw cut nice and straight with this fence is a snap.
The original question of the saw not cutting square vertically is due to the fact that the blade cuts in the direction its pointing. What has been missed so far is that if the arm doesn’t fall square to the vice table, the blade, even if adjusted as above, it will still not cut square vertically. To know if you’ve got this problem, using 6″ engineers square like in the photo above, place it so the blade of the set square just touches the tip of one of the teeth that is set toward the vice and clamp it up hard.
One of the most common reasons why a bandsaw is not cutting properly is because the blade does not have the proper amount of tension on it. Another cause of a bandsaw not cutting in a straight line is if the blade is too hot. As long as you have the right blade, the right blade tension, and everything is properly attached, your bandsaw should cut in a straight line.
bandsaw not cutting square Related Question:
Why won’t my band saw cut straight?
Band Saw: Why won’t my band saw cut straight? When the band saw cuts crooked, a dull blade, improper feeding, loose blade tension or not using a work piece guide could be the cause. Use the rip fence or miter gauge to guide the work piece uniformly through the cutting blade to make straight cuts.
Why is my band saw cutting at an angle?
A bandsaw has a spring that you tighten to keep the blade under tension. Your saw will probably have instructions for how tight to make the blade. This spring can loose its ability to properly tension the blade after some time, allowing the blade to twist in the cut.
What causes bandsaw drift?
Drift is cause because the blade buckles under the load. You can see that by stretching a ribbon between 2 points and applying a pressure to one of the edges, it will turn sideway easily. A sharp blade and high blade speed will help a lot with that.
How much tension should a bandsaw blade be?
For carbon steel toothed blades (cutting blades) this is typically 15,000 to 25,000 PSI. Slitting type blades typically are tensioned in the range of 12,000 to 20,000 PSI. In general bandsaw blades are never tensioned past 35,000 psi.
Why are my bandsaw cuts wavy?
The clasic cause for wavy lumber is pushing a dull blade past it’s limits. Sharp don’t get it.
Why do bandsaw blades break?
Even the best blades can fail if there is something else wrong with your bandsaw, and even a small misalignment of bearings or guides can put a twist in the blade as it goes around. Resulting in tension being applied in all the wrong ways which will lead to early breakage.
How long should a bandsaw blade last?
On average your bandsaw blade should last 6 months to as long as a few years depending on what your cutting with it. Make sure to match your blade strength and quality to the project and material your cutting.
Why do bandsaws wander?
Tim Inman: Because band saw blades ride on crowned wheels, they always have a little “camber” angle relative to the vertical axis of the wheel. This causes the blade to tip a little and makes the cut “pull” to the side.