Why Does My Circular Saw Keep Stopping?

Does your circular saw keep stopping? The most likely culprits are a slipping clutch, a lack of power, a loose blade, dust in the power switch, a blown breaker, or a dying motor. 

We’ll look at each of these. 

These are often the first power tools a new homeowner will buy (after their cordless drill).

Three years ago I bought the cheapest circular saw our hardware store had. 

It mostly gets used on random projects where we use it to cut soft pine wood. Come to think of it, I mostly use it to cut shelving for the wife’s Poshmark storage.  

This year, it got a workout.  I used it to build the new ToolTally office — a sheetrocked and insulated section of the garage for my computer. 

See Also: Table Saw vs. Miter Saw

Towards the end of that building project, I finally started dealing with my circular saw getting bogged down and stopping. In my case, it was a combination of a weak motor and a dull blade getting pinched by the wood.

Quick Troubleshooting Tips:

  • Try resetting (or replacing) the battery
  • Are you use the right blade? Is it a sharp blade?
  • Do you have enough power for the material/wood type? 
  • Are you experiencing kickback?
  • Is your kerf sufficient?

REASONS YOUR CIRCULAR SAW STOPS

Loose Blade

This one is simple. If the bolt into the arbor (the little nub that the saw blade goes on) has come loose, it will spin freely separate from the blade.

You need to align the blade with the arbor, make sure it is seated well, and then tighten the arbor nut. 

There should be a washer between the nut and the blade. Make sure that is in place so you get a tight grip. 

If the bolt has been replaced and is too long, this can also prevent a tight hold. 

Dull Saw Blade

This is another common problem. You are already suspicious of your blades. When was the last time you changed them? 

If your blades have been binding and leaving black marks on your finished project, it is likely that they are near the end of their life. 

Hardwoods require a blade with more teeth. These blades with more teeth allow your circular saw to take smaller “bites” of the wood, which is necessary when working with woods like Oak and Maple. 

Installing a new blade can be an easy fix. 

Tripped Breaker

If you are cutting along and your circular saw suddenly goes dead between cuts, look at the breaker box. It is possible that you tripped your breaker. 

Additionally, many garages have a GFCI outlet. Even if the outlet you are using doesn’t have the little “reset” button, it could still be on the GFCI circuit. Check the other outlets in your garage for a tripped outlet, and push the reset button in. 

Blown Fuse

Circular saws rarely have fuses in my experience. (A cheap circular saw will have circuit board components that can short out if overheated, so this acts like a fuse, but forces you to buy a new saw.) 

I haven’t yet found one with a fusible link or fuse that you can replace. 

Power Switch

What is more likely than a blown fuse is a power switch that is full of dust. Disassemble the handle (unplug the saw first!) and use an air compressor to blow the dust away. 

If your saw suddenly goes dead, and you didn’t blow a breaker, a dusty power switch is your chief culprit. 

Unsupported Wood

OSHA would have a hey-day with my unsafe practices. 

So often I make my cuts with one end hanging off the front step of the house. 

It’s dangerous, and it causes the board to sag in the middle where I am cutting, pinching the blade. 

Get yourself a couple of sawhorses and support both sides of the wood while making your cut.  Enlist someone to help when managing a large piece of wood. 

Don’t be like me. I’m dangerous. 

Depth of Cut

I often forget to adjust the depth of the cut. As long as the blade is adjusted low enough to give me a clean-cut, I don’t think about it. 

When using sawhorses, this can lead to me cutting into the sawhorse and stopping the blade. The same thing can happen with studs in the wall (only more disastrous!) 

This one is an easy fix: readjust the depth of cut if the blade keeps stopping. 

Clutch

Most circular saws have an anti-kickback device called a clutch which disengages when too much torque goes to the blade. The circular saw clutch protects the user and the saw from overload conditions. 

Kickback is generally a reaction to a blade that is pinched that causes the saw to lift suddenly as a reaction. 

Since an out-of-control saw would be deadly, the manufacturers install the blade two washers to create a clutch that allows the motor to “slip” when the blade is overloaded. 

This prevents the motor from burnout when the saw blade becomes locked by material. 

It is important to not over-tighten the circular saw blade since this can override the clutch behavior. 

The clutch is generally more of a symptom than a cause. Motor dying? The clutch will slip. Is the blade catching on the surrounding blade guard? The clutch will slip. Dull blade? The clutch is going to slip. 

I suppose the clutch could be worn, but it is generally a symptom, not the issue.  

Motor Problems

Saw motors tend to last forever. It is common for a good-quality circular saw to last 10-20 years. 

However, cheap saws can fail after a few years. 

If you are like me, you probably swung by Harbor Freight and picked up their cheapest circular saw to do that one-time task.  

If that is the case, then the motor may go bad more quickly. This is due to inferior ball bearings used in the motor housing and cheap brushes on the motor. (Most Harbor freight tools come with replaceable motor brushes). 

These cheap tools work well initially for straight, 90-degree cuts. 

But if you start trying to do beveled cuts, the saw is likely to bind. 

I hope I don’t come across as hating on cheap circular saws. Hell, I own one. Something like this Drill Master with a 10-amp motor is great for the occasional task around the house. 

But these cheap saws are also going to love softwood and sharp teeth.

If you suspect the motor, unplug the saw and try replacing the motor brushes. Also, test the motor for excessive play by wiggling the blade. Then, see how the circular saw runs when it isn’t under load. 

Weak/Dead Battery

Cordless circular saws use a lot of power. It is common to need to replace their battery with a fresh one. 

Try the old battery swap and see if you get going again. 

Sometimes, if you have dirty contacts, some rubbing alcohol on a Q-tip will clean those right up and restore power. 

But batteries have definitive end-of-life and it is possible that you need to get some new ones, especially if your charger displays a warning light when you try to charge it. 

STEPS TO SOLVE A STOPPED CIRCULAR SAW.

Whether you have a CraftsmanDeWaltSkilsaw, or some other power tools brand, here is a general troubleshooting workflow for blade stops

STEP 1: DISCONNECT POWER SOURCE

If you are unplugged (or the battery is removed), you won’t have to worry about accidentally triggering your circular saw into action and taking off a finger.  This is a quick way to prevent unexpected hazards.  

STEP 2: CHECK THE BREAKER

While unplugged, take a moment and check your breakers and GFCI’s. 

I like to keep a shop light handy that I can run around and test in the outlets. 

It’s so easy to make a dangerous mistake when checking for a flipped breaker while holding a circular saw in the other hand. Using a standard light that plugs into a household outlet is a much safer way to check for a working outlet.

cordless circular saw needs its batteries checked.

STEP 3: REPLACE OR TIGHTEN THE BLADE

Do you have the right blade for your type of wood? Is it sharp? Straight? 

Is it tightly attached? 

Wiggle it. Is there a lot of play in the motor? Does it turn well by hand?

Try tightening it a quarter turn and see if that resolves your issue. You’ll need a hex wrench and possibly an arbor wrench to keep the arbor from spinning (these normally come with your saw at the time of purchase). Some circular saws have a lock button in the housing that holds the motor in place when tightening. 

Keep in mind that worm drive saws require you to turn the nut clockwise to loosen it. 

Or, replace it with a new one.  

STEP 4: CLEAN THE POWER BUTTON

closeup of saw power button

If your circular saw is still not working, try taking the handle apart and blowing it out with an air compressor. 

You can also blow an air compressor into the motor vents and ensure that it is cleaned out well to prevent overheating. 

STEP 5: TEST IT OUT! 

Now, it’s time to test your your DIY efforts. Once your saw is back together and everything is in place, you can put the battery back as it should be and test it out with your woodworking project.

The majority of the time, one of these steps will have solves the problem. 

If these steps don’t work, your circular saw‘s motor is likely worn. It might be time to go shopping for a new tool!

FREQUENTLY ASKED QUESTIONS

My Circular Saw Blade Sticks and Burns My Wood. What do I do?

It’s time to put a new blade on your saw. Also, make sure the wood is supported during the cut and that you have the correct tooth count for the cutting you are doing. 

How do you keep a circular saw from binding?

The best way to avoid binding is to make sure that the pieces you are cutting are sufficiently supported to prevent blade pinching. 

How long do circular saws last?

A good saw should last 10 years. A cheap saw might die in a weekend of hard use.  How long they last really depends on the type of work you are doing and the quality of the circular saw.