Bandsaws are of course very useful tools in the world of woodworking, tools that can complete a wide variety of tasks. However, for a bandsaw to be able to complete these various tasks, it needs to be in great condition.
One issue that can arise with older units that are not well maintained, as well as newer ones that have not been set up properly, is that they don’t cut straight. Today, we are here to determine the various reasons why your bandsaw isn’t cutting straight, and what you can do to fix it.
Do You Need to Buy a New Bandsaw If Yours Isn’t Cutting Straight?
If your bandsaw is not cutting straight, unless there is something severely wrong with it, you will usually never need to replace it. Yes, you may need to replace various components, such as the blade guides and blades, but the bandsaw itself should not need to be replaced in most cases.
There may be other reasons why you need to replace a bandsaw, such as electrical issues or problems with the motor, but a saw that is not cutting straight is usually not a cause for complete replacement. As you will see below, there are many reasons why a bandsaw may not be cutting properly, and most of them have very simple solutions.
7 Reasons Your Bandsaw Won’t Cut Straight (and Fixes)
Let’s take a closer look at all of the different reasons why your bandsaw is not cutting properly. There are quite a few of them, and you are in luck because most of them have relatively easy fixes.
1. The Blade Tension is Incorrect
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. This is especially the case if the blade is too loose. A blade that is too loose can wobble around and twist.
This results in the blade going off course and not being tight enough to easily cut through the material. It’s not as much a problem if the blade is too tight (although that causes a different set of problems to arise, mainly excessive heat and the blade snapping.
To fix this problem, you need to check the tension of the blade. To do this, wear some safety gloves and push on the blade from the side. If you can push the blade more than 1/4-inch, you need to tighten the blade. Keep in mind that the recommended tension for your average carbon steel blade is between 15,000 and 20,000 PSI. However, other blades may require up to 30,000 PSI.
You need to check the manufacturer’s indications for the blade in question.
2. You Are Using the Wrong Blade
Another common cause of a bandsaw not cutting properly is if you have the wrong blade for the task at hand. For instance, narrow blades are great for cutting curves, whereas wider blades are best for cutting straight lines through thick stock. Using a thick blade on small stock usually is not much of an issue, but if you are using a very thin blade to try to cut thick wood, the blade can wander and go off course. Different blades have different amounts of teeth per inch, and this matters too.
The easy solution here is to do some research in terms of which blades are best used for specific purposes. Make sure that the blade has the right width, depth, and teeth per inch for the task at hand.
On a side note, related to this cause, if your blade is facing the wrong direction, although it may still cut to a certain degree, it certainly won’t cut as well as if the blade is facing the right direction. This might seem like a really odd mistake to make, but many beginners do mount their blades improperly when installing them. Needless to say, ensure that the blade is facing the right direction.
3. You Are Pushing Too Hard
The beauty of power saws is of course that they do the work for you. However, all too many people still try to really push the wood through the blade with excessive force. If you push the wood into the blade too much, the blade won’t be able to cut fast enough, which then results in the blade twisting, bending, and warping. This then results in the cut being crooked. The blade needs a way to release the added tension you are producing, which results in an uneven cut.
The simple fix to this issue is to just not push quite as hard. Just use light pressure to push the wood into the blade, enough to keep moving it forward, but not enough to bend the blade. On that same note, you do need to push a little bit. Holding the piece in place without moving it forward won’t do you much good either.
4. Your Blade is Dull
Perhaps one of the most common causes of a bandsaw not cutting properly is if the blade is dull. If you use the blade too much, or if you use one blade for the wrong purposes, those teeth will get dull and will not be able to cut as well. This results in added friction, as well as a slower and crooked cut. Moreover, if you are using a dull blade to cut very tough materials, things like resin and plastic, these can in themselves cause a blade to become dull.
A dull blade twists to the left and right because the teeth are forced to the side.
The one simple solution here is of course to replace the bandsaw blade (and make sure that you install the right one for the job at hand).
5. You Are Cutting Too Fast
Something else that can cause a bandsaw to not cut straight is if you are cutting too fast. It is important that the speed of the blade matches the material that you are cutting, as well as the blade that you are using. Generally speaking, metal needs to be cut at slower speeds, and wood needs to be cut at higher speeds. If you are sawing way too quickly, it will be difficult to achieve a straight cut.
The solution here is to do some research to figure out exactly what speed you should be running your bandsaw at for the blade you are using and the material that you are cutting. Usually, if you are cutting wood, the speech should be around 3000 feet per minute. If you are cutting metal, you want the speed to be closer to 1500 feet per minute.
6. Your Blade Guides are Misaligned
Exactly what the blade guides look like depends on the bandsaw in question, although these can be sliding blocks, wheels, or both. There is usually one on both sides of the blade and another guide on the rear of the blade.
If you notice that the rear blade guide is pressed against the blade when the machine is in use, then it is too far forward. If the rear blade guide is pushing the blade too far forward, it can shift the blade and thus cause uneven cuts. In terms of the side guides, if the blade is pressing into those too hard, it can also lead to uneven cuts. If the blade presses too hard into the side guides, it can also wear down the blade really quickly and even cause it to break.
The issue with this problem is that there aren’t any set measurements for adjusting the blade guides to the proper position. It all really depends on how thick the blade is. You will need to use some trial and error to keep adjusting the blade guides until they are in the proper position and at the proper distance from the blades.
This can be a fairly difficult process, so we recommend doing some more research on this front.
7. Things Are Getting Too Hot
Another cause of a bandsaw not cutting in a straight line is if the blade is too hot. If the material you are cutting is pinching the blade from both sides, it will cause a lot of friction, and therefore a lot of heat. When the blade starts to get really hot, it can warp and get bent out of shape very easily, and therefore no longer cut in a straight line.
Therefore, you need to ensure that you are cutting at the right speed, that you are using the right blade, and that everything is properly attached and secured. There are a variety of things that can cause high amounts of friction and heat to occur, so these all need to be accounted for. In order to prevent friction from occurring, you also need to ensure that all of the nuts and bolts are in good shape.
Other things you can try if the blade is getting too hot include slowing the RPMs down, using some lubricant, or taking short breaks in between sawing.
As you can see, there are many different reasons why a bandsaw may not be cutting straight.
That said, all of these problems come with relatively simple solutions that are easy for you to execute on your own. 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.