Why Do My Sanding Belts Keep Breaking?

When you are sanding and making some of the best possible-looking things you can imagine, you will usually reach a point where the belt breaks. Understanding why the sanding belt has worked perfectly before suddenly breaks can help you make smooth and perfect finished work. 

Your sanding belt breaks because you use one specific spot while sanding instead of using the whole belt. If the belt is tensioned too much or too loose, you can cause enough damage to the belt that it will snap as soon as you try to sand something even slightly hard. (Source: Wood Magazine)

These are just the most straightforward reasons that the belt on your belt sander may suddenly snap or break; however, the full range of reasons is a bit more complex. Each belt sander has its way of working, with many owners having to learn just why and how a belt broke with experience. 

What are the most common reasons a sanding belt breaks?

The reasons for your belt breaking are varied, it can be for something simple, or it can be because you have not done maintenance correctly. Understanding each reason and learning how to prevent them will help you to get more use out of all of your belts. 

Each reason can cause a different kind of breaking, with some belt snapping as soon as tension is applied to them. To prevent your belts from being damaged, even when not used, you need to know each of the reasons they may be damaged and how to prevent them from snapping in the future.

(Source: Stack Exchange, Saw Mill Creek, Lumber Jocks, Own Experience)

  • Age: A mistake that is often made is using a sanding belt that has been hanging for years on the nearby rack. Sanding belts have expiration dates, once they become too old, the sanding material may become crusty, or the belt itself will easily crack. 
  • Heat: The heat of the room and the heat that the sanding belt is exposed to will drastically affect the overall health of the belt. Ensuring that the piece you are working on does not become blisteringly hot and that the room is not constantly heated will prolong the belt's life. 
  • Humidity: Humidity is like heat, it needs to be perfectly balanced, or the belt will age faster, with high humidity weakening the structure. A too dry room causes the sanding surface to become too dry and cakey, causing the belt to become almost useless. 
  • Wear: All sanding belts will start showing wear and tear as you use them; belts cannot last forever. Even if you are using the belt, ideally, each time, the natural wear that you are applying will cause the belt to start breaking and losing much of the grit that it should have. 
  • Focused use: The most common issue, especially with first-time users, is the focused use of only one side of the belt. This causes a line to quickly form and the belt to cut through with the material you are trying to sand. 
  • Improper use: It may be surprising to those who have used their sanding machines for anything they can think of, but improper use can damage the belts. Finer grits will be damaged by still rough material, while the trick of polishing materials with the back of a belt will cause damage to the material. 
  • Too tight: Your belt machine may apply too much pressure when you are tightening the belt; this places constant stress on the belt. Once you come in with something to sand, it is similar to pulling something tight and cutting it, which is why belts in this position usually fail at their joins. 
  • Too loose: Usually, you can quickly tell when a belt is too loose as it slaps against the machine as it is spinning. When you start the machine, the belt will be prone to climbing off, snapping, or jumping around unexpectedly, causing damage to you and the machine. 
  • Wrong materials: A rough grit wood sanding belt may be able to scratch the surface of a piece of metal, but it will fail quite fast. While metal sanding belts can be used on wood, they will become clogged quite fast. Using the wrong sanding belt will quickly cause it to snap. 
  • Sharp edges: An unexpected nail or just a sharp edge on your metal piece that you need to make sharp will quickly cause the belt to break. Many people assume that there is little to no preparation required to use a belt sander, but anything unexpected can cause your belt to snap. 

How do you prevent a sanding belt from breaking?

Prevention is always better than simply looking for a way to fix things, with belt sanders and sanding belts usually working the best when adequately cared for. The knowledge to ensure that your sanding belts are always working correctly will enable you to save a lot of money.

Each issue with your sanding belts can be fixed with a few simple steps to ensure that they are always ready for you to use. We recommend applying each to ensure that you never have to grab a sanding belt and end up with something that spools wildly and out of control. 

(Source: Stack Exchange, Saw Mill Creek, Lumber Jocks, Own Experience)

  • Airflow: While working with your belt sander, you must ensure proper airflow to keep the machine and the belt cool. You will need to ensure that there is a fan providing constant airflow and that the belts are not constantly being dried out when not in use.
  • Proper Storage: Storing your sanding belts is an essential part of preventing them from being damaged. Usually, hooks on a wall within an enclosed room work the best as this saves the belts from being exposed to overly humid or hot situations that can cause damage. 
  • Check before use: Before simply throwing the belt onto the machine, it is always good to look at it, making sure there are no cracks or weak spots. Allowing you to comfortably use the machine without having your belt come flying out at top speed. 
  • Use entire belt: When you use the belt's entire width, you will get the full use out of your machine. The best way to do this is to move the parts you are sanding slowly from side to side, ensuring that the entire width of the belt is used.
  • Proper tensioning: The tensioning of your belt depends on the type of belt sander you have. You must ensure that you are doing it correctly and that the belts you are using can handle the tension you are applying, with an older belt sander relying on a swivel arm to provide the tension. 
  • Change belts: It's almost always a lot of work for people that want to get something done as fast as possible but changing belts will always be best. Using the right belt for the right job will mean that your belts will not simply snap or break as they are being used. 
  • Hand file: Not always a problem or solution with wood, but when using a belt sander with metal, we highly recommend that you deburr the edges. This will ensure that the belt is not cut up by sharp edges that would cut a little bit of the belt each time you use it. 

Why should a belt sander be kept moving?

A belt sander does not work unless it moves, having the belt being turned by large wheels, which allows the belt sanding surface to move rapidly. When moving at full speed, the belt sander can rapidly eat through a material, easily smoothening the edges of the material. (Source: The Spruce Crafts)

If the belt sander is not moving, you cannot sand anything; if you try to use the machine to hold onto the sanding belt, you will not be successful either. The belt will simply more or bend away as you are trying to sand the material, causing you to damage the sander and the sanding belt. 

If the belt sander is not moving even after turning it on, something else is wrong, and you will have to fix it. The fault is often over tensioning of the belt or a few loose bolts that are stopping the motion from the motor from turning the machine. 

How do you adjust the tension in a belt sander?

Belt sanders either work with a gravity tensioner arm or an adjustable tensioner arm, with the adjustable arm usually being installed onto smaller machines. Adjusting the tension with an adjustable arm requires turning the bolt, while gravity tensioner arms rely entirely on gravity. 

The more complicated a belt sander is, the more adjustable it will become, with many machines allowing you to adjust each roller with a simple knob. Adjusting on each part of the system will allow you to comfortably loosen the tension, change the belt's position, and re-center everything. 

Adjusting the tension of the sander will help to make your sanding belts last much longer, have the entire belt be more in the center, and allow you to sand at different angles. Many belt sanding machines allow you to sand at different degrees by adjusting the roller and the sanding platform. 

What happens when you are sanding on one spot?

As you are sanding in one spot, the sanding surface becomes worn down, eventually reaching the belt portion of the sanding belt. Once you have done this, it takes very little pressure to cut through the material with your workpiece, causing the entire belt to snap or become unthreaded. (Source: Fintech)

This happens most of the time when people with little to no experience with belt sanders use the machine. As they are not aware of the danger, they naturally focus so much on the material they are trying to sand, forgetting to look at how the machine they are using is reacting. 

In a few select instances, the sanding belt splits down the middle, leaving a piece of perfectly usable sanding belt on the machine. While it is tempting to keep using this piece, there is a higher chance of getting snagged or the belt jumping off the wheel when it can no longer be centered.

Can You Clean Up A Sanding Belt?

Yes, sanding belts can quite easily be cleaned off from all the material that would cause it to no longer be as abrasive. A belt-cleaning stick will easily allow you to clean the sanding belt while it is running by brushing away all the clogged materials on the belt. (Source: Fintech)

This is only something that has recently gained widespread popularity as the technique and technology to do it has been refined. Before using cleaning sticks, people would usually wash the belts using specialized cleaners that would not save time but would drastically help to save money. 

It should still be noted that while the sanding belt can be cleaned if there is a large piece of it missing or cracked, you need to put a new belt on. The cleaning techniques are meant to extend the life of a sanding belt slightly, but they will not make it last forever. 

Why Can't You Use Just Any Sanding Paper For The Machine?

Sanding belts have unique backing materials that allow them to withstand the tension and speed provided by the machine. Further, the grit is slightly different, not needing to be wetted once you reach finer sanding levels to have the sanding still work at the same level. 

While there are ways of turning normal sandpaper into something that can be used on a belt sander, these are not permanent solutions. If you have some waste sanding belts, it would be worth checking how thick they really are and how much they are different from normal sanding paper. 

Fortunately, you can use scrap sanding belts for sanding to be cut up to be used with other projects. This is something that a lot of people should note, as even with the best belt sanding machines, you will need to use some elbow grease to get the perfect finish. 

What Can Cause A Sanding Machine To Burn?

The most common cause is because the current belt you are using is quite old and worn out, while others may find that their belts are stored improperly. The burn can be from the machine being clogged with dust or that the belt is tensioned wrong, causing extra friction instead of turning. (Source: Fintech)

When replacing the sanding belt, you must clean out any of the machine parts that would usually not be exposed. This keeps the machine cool and stops it from burning and becoming a significant fire hazard that could cause many issues in the future. 

If you suspect that the machine or the belt is starting to run hot, it will always be worth it to check on everything. The machine can catch fire, and the materials you have sanded off can also easily catch fire, which will cause months of headache and trouble. 


Your belt sander and the belt running on it should last you quite a while, but you will find it breaking if you are not using or maintaining it properly. Many people have made the mistake of not properly caring for their machines and equipment causing sudden breaks while in use.

Whatever you do, please don't try to use the wrong side of the belt to sand something down; you'll only get headaches and sadness as the belt eats through the machine!

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