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Chainsaw Not Cutting Straight: Tips from a Professional

Everybody knows that a chainsaw is an excellent tool for garden owners, woodworkers, and foresters due to its strength and versatility. A well-sharpened chain can help it cut through different types of trees and wood in a matter of seconds. But an ill-maintained bar and chain could result in getting an angled cut than a straight one. I have encountered this problem more than once and will help with why it happens and how to fix it.

Chainsaw not cutting straight:

In general, there are several reasons why a chainsaw is not cutting straight. The chain is not sharpened on both sides, the chain’s tension isn’t adequate. The chain’s thickness is less than the groove’s width. As a result, it doesn’t stay vertical in the groove and cuts at an angle. The bar’s groove may have worn out. The bar rails may be uneven. This causes the chain to rest on the side instead of being vertical.

To better understand the problem and solve it, I will further look into the different causes.

Why does my chainsaw not cut straight?

If a chainsaw cuts at an angle rather than cutting straight, then the problem most certainly lies in the guide bar and chain assembly. The chain might not be sharpened, or the bar’s grooves might be loose. There can be various causes to it. And the bottom line is that the bar and chain aren’t properly looked after. Being a chainsaw professional, I can list down four different reasons that are causing this problem with your chainsaw:

● Reason 1. Chain is not sharpened properly:

It would be best if you begin fixing the issue by checking your chain’s condition first. If the chain isn’t sharpened properly, one side of it has longer teeth than the other. Your chainsaw will most certainly cut at an angle. Sharpening the chain properly would eliminate this problem. As a preventative measure, you should equally sharpen all your chain’s cutter teeth always. Such a condition is also caused when the chain hits a rock abruptly while running. The impact could damage the blades of one side of the chain.

● Reason 2. Chain is loose:

Sometimes the chain is too loosely fitted on the bar and flips on the side, thus cutting at an angle. Most chainsaws now come with a tension adjustment feature that automatically tightens the chain around the bar. Make sure you use it to adjust the chain’s tension so that it becomes snuggly fitted on the bar.

● Reason 3. Chain width is too thin:

The chain has shark tooth-shaped drivers who fit into the groove of the bar. If the chain’s drivers’ thickness is less than the bar’s groove’s thickness, the chain will wiggle in the groove instead of being properly fit. Due to this, it would shift sideways while cutting, thereby giving an angled cut. To check if your chain width matches that of the groove, try to flop your chain sideways. If it moves back and forth quite easily, your chain thickness is slightly less than that of the bar’s groove.

● Reason 4. Bar’s groove is worn out:

In some cases, the chain still flops sideways despite its width being equal to the bar’s groove. This occurs when the guide bar’s groove has worn out after continued use. The groove’s width slightly becomes more than its original width. This usually happens because of repeated impacts being taken by the bar while cutting. As a result, the chain wiggles in the groove and doesn’t cut straight.

● Reason 5. Bar’s rails are uneven:

The two edges that form the bar’s groove are known as rails. These rails support the chain on both sides and keep it vertical. Sometimes, the rails wear out due to fatigue, and as a result, one of the rails becomes higher than the other. Due to this, the chain rests on the lower rail and naturally becomes angled. This is another common reason behind chainsaws not cutting straight.

How do you fix a chainsaw that won’t cut straight?

Now we have looked at the various reasons why a chainsaw is not cutting straight. We will look at how to fix this issue:

● Fix 1. How do you sharpen a chainsaw that cuts crooked:

Before sharpening your chain, you need to inspect the chain links and the cutter teeth to verify if it’s a problem or not. Each cutter tooth has a small line on it which can help you to compare their heights. The line sets a lower limit for the height beyond which the cutter cannot be sharpened.

By inspecting all your cutters, you can get the idea if all of them have the same height or not. If you notice a significant difference, consider sharpening the higher ones. To sharpen the chainsaw chain, you can follow the procedure below:

  • Gather the needed tools: Before you begin, make sure you have all of the necessary tools on hand. A round file and a file guide are required for sharpening. To reduce the danger of injury, make sure the file includes a safety handle.
  • Adjust the chainsaw bar: If possible, adjust your chainsaw bar on a bench before continuing. When opposed to manually holding the chainsaw, this makes filing much easier and more efficient. Ensure the bar’s longitudinal side is secured between the wise fixtures, with the cutter teeth’ top side visible above. Also, while the bar is fixed, your chain should move.
  • File the cutter teeth: Using the round file positioned in the file guide, push firmly on the top surface of a cutter tooth at a 30degree angle. After that, move it across the cutter by pressing it tightly. It is important to understand that the filing should only be done in one direction. Moving the file back and forth repeatedly will cause it to be damaged. When filing, push the file away from the saw and not towards it. Also, keep it pressed forcefully until you feel the metal peeling away from the surface. Repeat the process on the remaining cutter until they are all completely filed.
  • File the depth gauges: While the cutter teeth are being filed, it is also critical to adjust the depth gauges so that we do not lose our cutting depth. Use a flat file and a depth gauge guide tool for this reason, and check that their top surface has been leveled according to the guide tool. Then, for the whole chain, repeat the operation.

● Fix 2. Tighten your chain:

If your saw still cuts crooked despite the chain being perfectly sharpened, consider checking your chain’s tension. If the chain sags unnecessarily, use the chain adjustment screw to tighten it. If it is still loose enough, you may need to break it open and remove a couple of links so that its length is short enough to fit snugly on the guide bar.a

● Fix 3. Find the chain with the right thickness:

Suppose you find out that your chain wiggles sideways in the bar’s groove. Consider checking its thickness and that of the guide bar’s groove. You can find out your groove’s thickness from the owner’s manual. Most chainsaw bars use chains having a thickness of 5/8th of an inch. Using a steel ruler, you can check your chain’s thickness, and if it falls short of 5/8th of an inch, you need to mount the correct chain on the guide bar.

● Fix 4. Flip the groove over:

When the chain still wiggles sideways despite being of the correct thickness. The guide bar is probably has worn out on one side. That side usually is the lower side which makes contact with the wood. It also makes sense as this side of the bar experiences the highest amount of fatigue and is most susceptible to wear.

A straightforward solution to this problem is to flip the bar over and remount the chain on it. Now the upper side of the bar, which has less wear, is on the lower side. Again, try to flop the chain sideways and notice if it still wiggles in the groove. You may notice that now on the lower side, it doesn’t wiggle much but does considerably on the upper side of the bar. That won’t matter to us since we are only concerned with the cutting side of the bar.

● Fix 5. Grind the uneven rails:

If the above steps still didn’t solve the problem, you might need to check your bar’s rails. If the rails seem uneven on inspection, such that one side stands higher than the other, you may need to grind it so that it evens out.

To grind your bar’s rails, I recommend using a powered grinding tool. By keeping it leveled, press it firmly against the grinder till metal has been removed from the higher rail and both rails stand even. If a grinder isn’t available for you, you can use a bench wise and a flat file to even out the rails.

Why does my chainsaw want to cut at an angle?

A chainsaw can cut at an angle due to several reasons:

  • Incorrect chain thickness
  • The dull chain on one side
  • Worn out guide bar
  • Uneven bar rails
  • Bent guide bar

It is important to know that all the cutting teeth of a chainsaw need to be of equal height and properly sharpened. If the chain is dull on one side, it’s most likely to cut crooked. Also, the chain should be snugly fit in the groove to not tilt towards any side. If it does due to any reason (less thickness, worn-out bar), the chainsaw will cut at an angle.

Can you straighten a chainsaw bar?

If you can straighten a chainsaw bar depends on the bar’s type and the damage. In most cases, chainsaw bars that are bent can be straightened by employing a proper technique.

Straightening a kink from a bar can be a tricky job. If not done correctly, you might end up damaging your bar. I will help with some methods which have worked for a lot of other owners and me. Use the following procedure:

For solid bars:

Solid bars are made up of a single sheet of steel. These bars are useful in dealing with hard timber. To straighten the solid bars, you can follow the below procedure:

  • Place the bar in a ‘press’: If a bar gets bent, the best way of straightening it without damaging its metallic structure is to apply a steady force large enough to straighten it slowly. I do not recommend using an impact force, as this may damage the bar’s rails. And the chainsaw wouldn’t fit in it. An arbor press or a hydraulic press are good options that can do this job for you.

    If a press isn’t available, you can use a bench wise and a 24″ pipe wrench to remove the kink. Just make sure it’s tightened enough between the vise grip thickness-wise.
  • Hammer the bar: Once the kink has been removed, place the bar on a flat anvil. Use a 4-pound dead blow hammer to straighten it out completely. Avoid using a ball-peen hammer as it may dent the bar’s surface.

    If neither the vise grip nor a press machine is available, there is still an effective way of straightening your bar simply by using a dead blow hammer and a bar hook tool.
  • Use a bar cleaner handle: A bar cleaner hook tool removes debris stuck in the bar’s rails. Its thickness is the same as the groove’s width. By placing this tool between the rails, you can hammer out the kink without damaging the rails. Make sure you use a dead blow hammer for this job.

For laminated bars:

Unlike solid bars, laminated bars use thin steel sheets riveted or welded with each other. Such bars are effective against kickbacks and provide good cutting control. Removing bends from a laminated bar is quite difficult. However, if the kink is not that significant, you can still give it a try. Just make sure that you have removed the kink using a press machine or a vise grip.

  • Use rubber padding: Hammering a laminated bar can be tricky as it may further the damage to the bar. One method that has helped several users is placing rubber padding under the bar while hammering it with a dead blow hammer. The rubber would avoid causing damage to the bar due to the hammer blows.

If it still doesn’t straighten out completely, it is better to invest in a new guide bar of the correct size.