How to Sharpen Your Saw Blades

How to Sharpen Your Saw Blades

Woodworking projects become a lot easier when you’ve got sharp blades to cut your material with. Sure, you can hack your way through a piece of lumber with a dull cross-cut saw or circular saw blade, but it tends to tear up the material and won’t give you the kind of clean edges you’re looking for in your finished piece.

When things start to get dull, you don’t always need to replace your saw blades — just sharpen them. Here are some tips and tricks to help you sharpen your tools so they’re always ready when you start a new project.

Identify Your Blades

First, before you break out the files and sandpaper, you need to identify what type of blade you’re dealing with. There are 31 different types of saws, and while you probably won’t come across all of them in your woodworking — or even in your lifetime — it’s helpful to be able to identify them so you know what you’re trying to sharpen. For the purposes of woodworking, you’ll likely spend most of your time using circular saws, cross-cut saws, and rip saws, so, for now, we’ll focus on how to sharpen these three.

Sharpening Circular Saw Blades

There are two common types of circular saw blades on the market — steel-toothed, and carbide-tipped. The latter needs to be sharpened professionally or re-tipped if they start to become dull. The material is hard enough that it would destroy most steel sharpening files. You can sharpen them with a diamond file but you need to be careful not to round the tips.

For steel-toothed blades, you need a sharpening file. Again diamond files are probably going to give you the best result. Pay attention to the bevels. They’ll alternate between the teeth, so you’ll want to sharpen one side of the blade, using the file on every other tooth, before flipping it over and sharpening the other side. Hold the file at a 20-degree angle and give each tooth four to six consistent strokes.

They do make automatic sharpeners for circular saw blades that do the job faster but these can be harsh on the metal, weakening the temper by heating the metal and making the teeth lose their edges that much faster.

Sharpening Cross-Cut Saw Blades

Cross-cut saws are designed to cut across the wood grain and have teeth with alternating bevels at about 30 degrees along the length of the blade. To sharpen these blades, you need a flat file, a triangular file, and somewhere to secure the saw so it doesn’t move. Then look at the teeth. You’ll see the bevels alternating along the length of the saw. Start by moving down the length of the blade along the top of the teeth with the flat file. This evens them out and gives you a starting point. You should now have a shiny flat spot on the top of each tooth.

Then take your triangle file and fit it in between the teeth at a 30-degree angle. You will be able to feel and see where these bevels sit. Then use a few strokes on either side of the bevel — still, at that same angle — you should see that flat shiny spot disappear as the point returns.

Sharpening Rip Saw Blades

Rip saws, unlike their cross-cut cousins, are designed to act more like tiny chisels, chipping through the wood instead of cutting it. Instead of alternating, their teeth are straight and you sharpen them by filing flat across the blade. Just like with the cross-cut saw, you’ll start by taking a flat file across the top of the teeth to create that flat spot. This is called jointing.

From there, you’ll file across the flat of the tooth, eliminating the jointing by holding your file at a 5-10 degree angle. As soon as the flat spot from the jointing disappears, you know the tooth is sharp again.

When to Replace Your Blades

Sharpening can help you get the most out of your blades, but eventually, they’ll reach the point of no return. When should you replace your saw blades?

Unfortunately, there is no exact timeline for replacing blades, but in general, if your blades are burning or chipping the material, binding frequently while cutting or causing kerf tearout, it might be time to replace them.

Don’t throw away your dull blades though! While they might not be useful for your projects, they can help prevent you from tearing up your good blades if you’re cutting through lumber that might have nails in it.

Looking Forward

You will use and replace many saws and saw blades in your lifetime. Learning how to sharpen them can help you get a little more bang for your buck and keep you from spending all your hard-earned cash on woodworking tools.

Scott Huntington is a writer from central Pennsylvania. He enjoys working on his home and garden with his wife and 2 kids. Follow him on Twitter @SMHuntington

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