Table saw burn marks are caused by excessive friction between the blade and wood. This most often results due to misaligned table saw components or poor technique; however, there are several other causes that are less common. Below are 7 causes that may explain why your table saw is burning wood.
- Misaligned rip fence
- Poor technique - too slow of a feed rate
- Dirty blade
- Dull blade
- Incorrect blade type
- Arbor out of alignment
- Warped blade
Besides the above, there are other factors you’ll want to consider, since these will influence your saw’s performance. The below are less likely to cause burn marks or even affect the performance of your table saw and its blade, except in some unique circumstances.
- Type of wood being cut
- Internal stresses in the exact piece of wood you’re cutting
- Build up in the dust collection system
Rip fence out of alignment
One of the most common causes of burn marks when using a table saw is using a rip fence that’s out of alignment.
In an ideal world, your rip fence would be almost 100% perfectly parallel to the blade. ‘Almost,’ in that, towards the end of the fence, it tapers off slightly, as in a millimeter, maybe 1.5 millimeters.
This helps to prevent the wood from binding on the blade. The slight taper ensures you will not pinch the wood between the rear of the blade and the fence. Second, the slight taper allows just enough room for the wood to expand if there are any minor internal stresses being released.
When the fence gets closer to the blade, the farther to the rear it gets, the fence is creating a choke point for the wood between the blade and fence. This creates unneeded and dangerous friction the blade has to spin through. The added friction causes burn marks.
How to realign your rip fence
For any table saw, realigning the rip fence follows the same general steps below:
- Reset the fence by fully extending it or removing it and reconnecting it.
- Measure the distance from the front of the miter slot to the front of the fence and then from the rear miter slot to the rear of the fence.
- If there is a significant difference between these two numbers, adjust the fence accordingly.
- Adjust the fence as you normally would and move 8”-10” closer to the blade. Measure again.
- Assess the measurements and compare them to the previous measurements.
Realigning the rip fence starts with diagnosing why it came out of alignment to begin with. This starts with understanding the mechanism your table saw uses. For lower end models, like this Craftsman table saw, it’s a clamp like system, which doesn’t tend to be incredibly accurate to begin with.
For others, like the Dewalt DWE7491, a rack and pinion system is used. Finally, for the professional grade table saws, a ball bearing system is typically used.
Rack and pinion style fences can wear out over time or have debris built up in the rack or pinion teeth. What we have found is that these fences have just enough ‘play’ in them out of the box that they may cause some issues. This is rarer, but it is possible.
To fix any alignment problems, start by cleaning and waxing the table top, rip fence, and any components top to bottom. If you can disassemble your rip fence, do so and clean the parts with warm soapy water and dry immediately. Use compressed air to blow out any hard to reach places.
Poor technique - too slow of a feed rate
Feeding stock too slowly through the table saw results in added friction that causes burn marks on the workpiece. If you are feeding the wood smoothly at a good pace without causing kickback, your issue may be related to the sharpness of the blade or an alignment issue.
However, if you’ve gone through and re-aligned your rip fence and you know your blade is sharp, the issue is likely your technique. Always use a push stick when possible and push the board through the saw efficiently, but smooth.
The wood should not have time to sit near the blade after the cut has been made. Continue to push the stock all the way through and past the riving knife.
Dirty, dull, incorrect, or damaged blade
If the blade is dirty, dull, damaged, or you’re using the incorrect blade, you may see burn marks appear on the wood. Each of the aforementioned factors can affect how the blade moves through the wood and its overall interaction with the wood.
A blade that is dirty and has a buildup of glue, sap, or other gunk cannot move as smoothly through the wood you’re cutting. The build up can heat up and either cause additional marks or retain heat through the wood. Luckily, this is an easy fix.
A quick bath in a tool detergent like Trend’s Tool and Bit Cleaner or CMT’s blade and bit cleaner will do the trick.
Trend Tool and Bit Cleaner
Gently releases grease and grime without the need for harsh abrasives, lye, phosphates, bleach, dyes or perfume, making it safer and easier to use than other cleaners.
A dull or damaged blade will have the same effect. If you are still using the stock blade that came with the saw, you’ll want to consider upgrading - the stock blade often isn’t worth sharpening and, for some models, can’t be sharpened.
Warped Blade
This is a lesser common issue and is rarer to find on modern blades. An easy way to rule out a warped blade is to remove the blade from the table saw and then place it on a flat surface.
If the blade has any wobble or you can see it bowing above the surface, you have a warped blade.
Another option is to take a combination square, place it perpendicular to the miter slot and then run the edge of the ruler to the tip of the blade. Unplug the saw. Lock the ruler in place and slowly spin the blade by hand. Be careful not to cause the left and right movement in the blade as you’re spinning it.
If there’s significant contact between the tip of the blade and combination square, you may have a warped blade. Other possible causes of misalignment here may include misalignment of the arbor or a non-flat arbor washer.
Warped blades tend to be less common on modern blades because better materials being used, designs in the blade (ex. Heat expansion slots), special coatings, and other features.
Incorrect Blade Type
The stock saw blade that is included with your table is likely a general purpose blade. Something that has around 24 teeth and is good enough for general cutting - think standard plywood or 2x4s.
This blade cuts coarsely and cuts fast. However, a rough finish isn’t probably what you’re looking for.
Let’s take a deeper look.
Most blades are labeled for ‘ripping’, ‘crosscutting’, ‘combination,’ or ‘general’. Others may be labeled as ‘laminate’, ‘fine finish’, ‘melamine’, etc. All these labels are useful to narrow down your decision quickly.
However, I encourage you to look at the details of each blade you’re purchasing so you can understand how exactly it’s going to perform when spinning.
Here are the points you want to pay attention to:
- Tooth grind and shape
- Tooth angle
- Hook, aka rake
- Tooth count
- Kerf
- Coating (if applicable)
Woodcraft.com has an excellent article that better breaks down the topic, but here’s some general advice for the burning issue you have currently.
- If, up until this point, you’re satisfied with the performance of the blade you have, buy one that’s in the same category and has the same tooth count.
- If you’re frequently working on projects and this is an investment, it’s worth spending $100 to $150 on a good blade. You’ll notice a significant difference in performance. Higher end blades can be re-sharpened several times before needing to be replaced.
- If you’re completely lost and don’t know what to buy, a higher-end combination blade will solve 80-90% of your issues and probably get very close to the results you want.
Arbor out of alignment
This is a rare issue, but if you have tried everything else, here’s how you’ll troubleshoot it.
- Raise the blade to its highest setting, then remove the blade, arbor nut, and arbor flange. If your arbor nut is stuck, check out this article to help remove it.
- Set a drop dial gauge so that it just barely makes contact with the flat side of the arbor.
- From underneath the saw, rotate the arbor and watch for any movement on the dial.
Any movement on the drop dial beyond 0.002” is likely to be contributing to the alignment issues you’re seeing on your saw.
How to remove table saw burn marks from wood
- Make a thin second cut
- Run the edge through the jointer
- Hand sanding
Unfortunately, there isn’t an easy way to remove scorch marks from the wood unless you make a secondary cut to remove the layer of burned material.
If you’ve corrected the issue on your saw and ran another test piece through, you may move the fence a hair over to remove the edge that has been burned. The burn is likely not deep and all that needs to be removed is a saw blade’s width or half a saw blade’s width to get rid of the burn mark.
Otherwise, you will need to sand the mark out by hand.
This will take some time and it’s not easy.
The issue with using a belt sander or random orbital on the edge is taking off too much. It’s harder to control these tools on a small surface area and it’s very easy to remove too much material.
FAQ
What causes a table saw to burn wood during cuts?
A table saw blade spins up to 6,000 revolutions per minute, which creates enormous amounts of heat from the friction between the blade and wood. If there is excessive friction due to misalignment, a dull blade, or other causes, the increased friction will generate enough heat to burn through the wood.
Is it dangerous to continue cutting when the wood starts to burn?
Yes, if the wood is burning during your cut, something is wrong. It could be your equipment, your technique, or something else. It’s recommended to discontinue any cutting, disconnect the saw from power, and troubleshoot the issue.
Can a dull blade lead to burning, and how often should I sharpen or replace it?
Yes, a dull blade can lead to burning. If the blade can be resharpened, you should seek to sharpen the blade when you rule out all other issues and continue to require additional force to make the cut. The frequency of sharpening will depend on how often you use your saw, the types of wood you are cutting, and your maintenance habits.
How does the type of wood influence the chances of burning? Are hardwoods more susceptible?
Some species of wood are more susceptible to burning than others. How well the wood is seasoned also is a factor. Softwoods that have a higher sap content can ‘gum up’ the blade if not seasoned well enough. Hardwoods like Cherry, Maple, and Purpleheart are notorious for getting burn marks.
What role does the fence alignment play in preventing wood burn?
Fence alignment is a major contributor to creating excessive friction on the wood. If your fence gets closer to the blade as it nears the end of the table, even by just a few hundredths of an inch, this is enough to create excessive friction that results in burn marks.
