Jigsaws are capable of cutting very intricate designs and patterns. But if you’re having difficulty cutting a straight line using your jigsaw, you’ll want to know why.
There are 5 reasons why a jigsaw will not cut straight. These include the use of low-quality blades, putting too much stress on the jigsaw and blade, using an outdated jigsaw that isn’t fitted with a guide bearing, using a cutting edge that isn’t perfectly straight, or a jigsaw that is damaged and contains faulty parts.
I’ll now help you to identify the problem you have with your jigsaw, with a repair guide you can carry out yourself cheaply and simply.
1. Low quality blade
Although you might think it’s a small matter and not something that would make a big difference to your jigsaw cuts, it is always worth buying good-quality blades as cheaper ones do not cut nearly as well as more expensive ones.
This is because more expensive ones are manufactured to higher standards, have much thicker blades, stay sharper for a longer period of time, and are much stronger because of being made from more sturdy alloys.
Cheaper blades are usually made from much poorer quality alloys which are not as tough, bend easily, and do not stay sharp for as long or cut as well.
Always look to purchase blades that have at least twelve teeth as this will result in a much more precise cut.
2. Putting too much pressure on the blade
When you’re using your jigsaw, you should always take care not to put too much pressure on the jigsaw as excessive pressure puts stress on the blade.
If you use too much pressure, you could cause the blade to bend, which could result in a curved cut instead of a straight one.
In addition, even a small amount of lateral pressure could cause your blade to veer off, again cutting where it wasn’t supposed to.
Therefore, when using a jigsaw, you should always use a steady downwards pressure without forcing the machine, pressing against the guide so that the jigsaw remains straight, which ends up in a neat and tidy cut.
3. Outdated and lacking guide bearings
Before the 1990s, it was impossible to cut straight or square with a jigsaw. This was because at that time jigsaws were not fitted with a guide bearing.
A guide bearing is a support point that is designed to prevent unwanted movement of the blade. Without it, there is nothing to keep the blade moving in a straight line.
This is why old jigsaws would often veer off and not cut straight, which spoiled projects and frustrated the user. If you own a jigsaw that is pre-1990s, you’ll definitely need to invest in a modern jigsaw fitted with a guide bearing.
4. Cutting edge isn’t straight
Don’t be tempted to use a piece of wood as a cutting edge. If the edge isn’t perfectly straight, it will probably ruin your entire project.
You should always try to use a metal or plastic straight edge if you can. If you have no metal or plastic edges to hand, a ruler or level is also suitable to be used as a cutting edge.
You should always make sure that you secure your cutting edge with clamps to ensure that there’s absolutely no movement when you’re making the cut. Always cut against the cutting edge and guide bearing so that your cuts are completely straight.
5. Damaged or faulty parts
One of the most important things to consider if your jigsaw stops cutting straight is whether or not the jigsaw is faulty or if any of its components have become damaged. There are many different components that could be the reason why your jigsaw is no longer working properly.
One of the first things that you should consider is whether or not the guide bearing is broken. If it is damaged, then it will no longer provide the support that the blade needs in order to cut straight.
To check whether the guide bearing is the problem, you will need to remove the screws in the jigsaw so that you can open the base.
Once you’ve gained access to the base, you will need to remove any clamps and lift the assembly out of its case. You will also need to remove the reciprocating shaft to locate the control bearing.
If the bearing is broken, it will need replacing. To do this, you’ll need to remove the O-ring from the existing bearing and slide it onto the new one. Insert the new control bearing and reattach the reciprocating shaft.
Now you’re ready to put the assembly back into its case, put the clamps back on (if present), put the case back together, and reattach the base.
If you’ve checked the guide bearing and that isn’t the problem, then you should check the blade support. This is designed to support the blade, preventing it from moving backwards or sideways.
Non-faulty blade support should be in contact with the back of the blade. If it is worn or damaged, then it will fail to support the blade, allowing it to move backwards and sideways.
If it is damaged and needs to be replaced, you’ll need to use a hammer and punch to remove the pin that is holding the support onto the jigsaw. Once you have removed the pin, you can remove the old blade support, install the new one and put the pin back in with the hammer and punch.
Inside the blade support is a roller. Depending on the model of your jigsaw, you might be able to just replace the roller instead of the entire blade support.
If the roller is damaged or worn, you will need to use a hammer and punch to remove the pin that is holding it to the blade support.
Once you’ve removed the pin, you can easily replace the old roller with your new one. Once installed, reinstall the pin with the hammer and punch.
Another reason that your jigsaw might not be cutting straight is if the blade clamp is damaged. The blade clamp supports the blade and absorbs the shock of cutting. If it has become damaged, you will likely end up with curved cuts.
To install a new clamp, you’ll need to remove the cutting blade and the screws that attach the blade clamp to the jigsaw. After you’ve installed the new blade clamp, make sure to secure it tightly with the screws. Now reinstall the blade.
Your jigsaw is fitted with something known as either a base, shoe, or plate. These are all exactly the same thing, but the name changes depending on the manufacturer. Here, we’ll refer to it as the base.
Your jigsaw will not cut straight if the base is bent or damaged, so it’s always a good idea to inspect it.
If you’re not entirely sure whether the base on your jigsaw is damaged, then you need to put it on a flat surface to check whether it’s level. A base that is not damaged will be in contact with the flat surface across all of its surface. If any areas are not making contact, then it is probably warped.
If it is warped, you’ll need to reinstall a new base by removing the screws that are holding the existing base and replacing it with a new one.
Consider a circular saw
If you’ve checked every possible reason as to why your jigsaw isn’t cutting straight and still have not found the answer, then you should consider using a circular saw. Making straight cuts with a jigsaw can be a difficult task even if it isn’t damaged.
Circular saws are better suited to making straight cuts and will make your life a lot easier. Check out the current prices of circular saws on Amazon now.