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.
Having the blade ride centered just behind the gullets between teeth makes a huge difference, as well as learning to set the blade tension properly. Normally the bearing behind the blade should not be in constant contact with the blade, except when you are pressing the work into the blade. You can check this with a transparent protracter, but making one cut with a wood block, then flipping it upside down, checking to see if the blade still fits in that slot.
Dull blades require more power to feed into the blade, which can cause it to turn left or right – and that’s when crooked cuts take place. Setting up the blade guides properly also helps in easing the situation, but it may still allow some crooked cuts since guides are not the main issue. The point of the edge should face down for a vertical bandsaw blade, then the hook of the teeth for horizontal bandsaw should point in a way that they enter the workpiece as the blade moves.
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.
There are a lot of cutting forces working on that thin piece of metal that is a bandsaw blade, so if you can’t attain sufficient tension then nothing will be right! Generally speaking we recommend 30,000 PSI of tension for bimetal blades, though in most applications you won’t start running into serious problems until you have half that tension. Tooth chipping would in fact be the #1 cause we see for blades not cutting square, and particularly where they cut on a curve. Just as happens with a worn blade, too many teeth actually reduces the material removal power of the blade and if combined with an over-optimistic down feed rate, won’t speed up the cutting so much as cause the band to twist and writhe itself crooked within the cut.
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.
why does my bandsaw cut crooked Related Question:
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 band saw 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.
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 is my horizontal band saw not cutting straight?
Make sure the blade is running in the correct direction. On machines powered by three phases power so it is common to get the wiring reversed and have the blade running the wrong direction. On all vertical blade bandsaws the working portion of the blade should go down. This forces the workpiece down into the table.
How tight should my bandsaw blade be?
The blade should deflect no more than 1/4 in. A good place to begin is to tension the blade until the meter reads proper tension for the next wider blade. For example, if you’re tensioning a 3/8-in.
How do you straighten a bandsaw blade?
How to straighten a bandsaw blade? It is risky but if it’s absolutely necessary, a temporary fix to straighten a bandsaw blade can be done by placing it on an anvil and gently tapping it flat with a nylon head hammer/mallet or using a pair of gas pliers to straighten out the blade.
Why does my bandsaw blade wobble?
The blade on a saw left idle for long periods of time can leave an impression in the rubber tire which might cause erratic tracking. Purchase and install aftermarket replacement tires. (Search for “bandsaw tire” at woodcraft.com.) If you still see a back-and-forth motion, the culprit is probably the wheel itself.
Why does my bandsaw cut to the right?
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.