Bandsaw Not Cutting Straight (Causes & Fixes)

Adjusting and correcting the problems of cutline drift on bandsaw.

The other day, my friend called in asking me to look into his bandsaw because it was not cutting straight. I told him that there are several reasons why a bandsaw would not cut straight. It might be a case of a dull saw blade, loose blade tension, improper feeding, or non-usage of workpiece guides like miter gauge or rip fence. So, you should figure out among these reasons the cause of the inability of your bandsaw to cut straight.

Bandsaws, however, come in a wide variety of models and brands. You will find metal bandsaw, meat bandsaw, wood bandsaw, benchtop bandsaw, horizontal and vertical, and many other bandsaw types. Yet, the usual culprits when it comes to a bandsaw not cutting straight are the abovementioned factors.

Primary Causes of a Bandsaw that Is Not Cutting Straight

As mentioned above, some factors cause the blade drift and its inability to cut straight. As an owner of a bandsaw, it will help if you are familiar with the following major causes of the bandsaw blade’s inability to cut straight:

Too Much Force Applied When You Cutting

When cutting materials using a bandsaw, you need to balance the cutting speed and the force you apply. If you force the material into the saw blade, chances are the saw blade might twist while cutting. This twisting produces a crooked cut. Hence, you only need to apply enough pressure when feeding the material you want to cut. In this way, you let the saw blade do its job with not much effort on your part. 

If the saw blade is dull, you will sometimes get impatient and push the workpiece harder onto the saw blade. The saw blade will likely twist, producing a crooked cut likewise. In such a case, you must replace the saw blade or have it sharpened. 

Crooked cuts are sore to look at. Moreover, if the cut is not straight, you need to redo the cut, causing you downtime. But if the saw blade is not dull, you can patiently feed the workpiece without forcing the issue. Practice getting the hang of the feeding process. Remember that the less tension you apply on the saw blade, the less likely it will twist and cut crookedly. Besides, it will help if you also use help guides to steady the material and cut straight.

Loose Blade Tension

Loose blade tension can also be a primary reason why a saw blade is not cutting straight. The saw blade stretches itself between the two wheels, and if the tension is not sufficient, it will not likely cut straight. You can check the blade tension by wearing a gloved finger and pressing in on the blade side. If you see that the blade tension is loose because you can still push it beyond a quarter of an inch, you need to tighten it up. 

To fix this problem, you need to check the tension of the blade, as mentioned above. Wear your safety gloves when trying to push the saw blade. The range of recommended blade tension for a carbon-steel blade is between 15K psi to 20K psi. 

Yet, saw blades vary depending on the materials they are made of. If the tension is higher than the range mentioned above, you can decrease the blade tension. But if it is lower than the range noted above, you need to tighten the saw blade.

Incorrectly Installed Saw Blade

Another reason why the saw blade is not cutting straight is an incorrectly installed saw blade. You can quickly know if the saw blade’s teeth are pointing in the right direction. Using a metal or woodcutting saw blade, the hook points downward, especially for the vertical bandsaw. If you use a horizontal bandsaw, the saw blade’s hooks enter the workpiece first. So, the hooks must face the material. 

You might be asking whether you can flip the saw blade inside out. Yes, you can if you want to get a fresh cutting edge from your saw blade. If your saw blade is a honeycomb-style blade, you will see that the saw blade teeth seem to run backward. 

It will be best to ensure that your saw blade gets appropriately installed and that its teeth are facing the right direction to fix this issue. If it got it wrongly installed, you should flip the saw blade over and re-install it.

Saw Blade Guides Are Wrongly Aligned

The bandsaw blade guides usually feature three components or elements. You’ll find the first two components on each side of the saw blade. Additionally, the other one gets situated at the saw blade’s rear. Guide components can come in forms like sliding blocks, wheels, or a combo of both. The saw blade should not be touching the guides during operation. 

If the guides are misaligned, you can adjust them. Yet, there is no fixed set of measurements for blade guide adjustments. So, you only need to adjust the guides based on the saw blade’s thickness. You can move the guides farther or closer to the blade. Moreover, you can take the block off to move the blade guides. After adjusting, you can put back the block.

Wrong Cutting Speed

You may fail to cut straight using the bandsaw if you are sawing too fast. So, before you start cutting, you should figure out beforehand the appropriate speed for cutting the material. If you cut metal, for example, you can go slower. While if you would cut wood, you can go faster. You should speed up or slow down depending on the material you are cutting and the blade you are using. 

If you are sawing too fast, you should adjust the bandsaw speed. Check the adjustment system of your bandsaw. If you cut wood, you should maintain your speed around 3000 FPM. If you are cutting metal, you can slow down up to 1500 FPM.

Bandsaw Wheels are Incorrectly Aligned

After checking if the saw blade has the proper tension, you should also check if the blade tracks on the wheels. The support wheels of the saw blade in high-speed machines come with a rounded surface or crown. When operating the bandsaw, the saw blade should run on the crown’s center or near the crown’s center. It should not be too close to the read edge or front of the wheel. 

If you see that the saw blade is not on the wheel or barely on the wheel, you need to align the wheels. You should check beforehand the blade guide adjustments before you tinker with the blade wheel adjustments. The reason is that the misaligned guides can also cause the blade to move on the wheels in an incorrect manner.

The bandsaw guides do not hold the saw blade in place. They are there as backups. If your bandsaw is well set, you may not have any need for the bandsaw guides. 

On the other hand, the bandsaw wheel’s crown keeps the saw blade in place. The saw blade will tend to move to the highest wheel point or the crown or its top. If you got worn-out wheels, the saw blade would go awry, not knowing where to go. This is one reason why the saw blade has difficulty cutting straight. You can resurface the blade wheels if they are too worn out before you set the guides.

Wrong Wiring

As you try to learn more about the power setup of your bandsaw, you will discover that your bandsaw necessitates three power phases to operate. Such three phases can make you make mistakes with its wiring. If you run the bandsaw with the wrong wiring, you would find the saw blade running in the opposite direction. 

If you are using a vertical bandsaw, its saw blade should move downward when cutting. This downward movement holds the material on the tabletop. If it moves upward, it will cause the material to get ejected from the tabletop. With the horizontal bandsaw, the saw blade’s edge should move towards the motor wheel. If your saw blade is moving in the opposite direction, it will help to check the electrical wiring of the bandsaw.

Bandsaw Wheels are Worn Out

If you’ve tried checking all the tips for troubleshooting your bandsaw, but still the bandsaw blade doesn’t cut straight, I think it’s high time for you to check the wheels of your bandsaw. The bandsaw comes with a crown for supporting the saw blade. The saw blade ideally should be running at the crown’s center. It is acceptable if it veers off a quarter of an inch to an eighth of an inch from the crown’s center. 

Yet, if the saw blade struggles to stay in the proper position, it will be best to tinker with the wheels and adjust them. But as mentioned above, before you tinker with the wheels, you should first check the blade guide. However, if it is not the guide, then it must be the wheel. Check if the wheels got worn out. Such worn-out wheels can cause the saw blade to deviate much from the right track. You can crown the wheel if needed. Replace your wheels if they are too old likewise.


Tips on Adjusting Your Bandsaw


Conclusion

Like the table saw, the bandsaw may exhibit an issue when cutting in a straight line. Yet, once you experience such a problem, you can always go back to the possible reasons mentioned above and check if any of the reasons noted above causes the inability of the saw blade to cut straight. In this way, you can adequately troubleshoot your bandsaw and zero in on the exact reason for the failure of the bandsaw to cut straight.

You might get daunted when tinkering with your bandsaw, thinking you’re not dexterous enough when it comes to fixing things. Moreover, the bandsaw is a huge machine that could be challenging to figure out. Yet, if you know the possible reasons, you can rule out each improbable reason and zero in on the exact reason behind the inefficiency of your bandsaw blade.

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