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Plywood has many uses from subflooring to cabinets. While there are some projects that you can get away with a bit of splintering on the edge, there are others that you’ll want to cut cleaner.
With this guide, you’ll learn how to cut plywood with a circular saw without splintering.
What Causes Tear-out and Splintering on Wood
Splintering and tear-out are often used synonymously – and they’re more likely to occur when you’re making a crosscut in the plywood.
This is because the wood fibers in the veneer are oriented so that they run the length of the board, so you have to cut through all of them. With a rip cut you’re more likely to slice along with the fibers.
But why does cutting across the grain lead to splintering? Your compact circular saw rotates clockwise and the teeth come up through the wood.
This puts an upwards force on the fibers, and splintering occurs because the fibers aren’t supported on either side so they bend.
As the fiber bends, it pulls up at the edges of the cut and eventually breaks off instead of actually being cut by the blade.
The two causes of splintering therefore are the lack of support by the surrounding fibers, and the blade bending the fibers before it cuts them.
How to Cut Plywood With a Circular Saw Without Splintering
There are exactly two ways to prevent splintering: increase the support between the fibers, or make the blade cut the fibers before it bends them.
With a couple of exceptions you can’t change how the wood is structured and supported, so most of the following tips and tricks are aimed at making your blade cut better.
1. Use the Right Blade
The blade that came with your mini circular saw is great for hacking through 2x4s, but for making smooth, finished cuts on plywood you’re going to need an upgrade.
There are a few different things you want to look for in a blade:
- High tooth count
- Carbide-tipped teeth
- Thin kerf
When it comes to saw blades the higher the tooth count, the finer the cut. A blade with fewer teeth will make the cut faster but you’re much more likely to get splintering and tear-out.
Carbide is an alloy of tungsten and carbon and it’s commonly used for saw blade tips. This is because carbide is stronger and more durable than other metals, and it also takes a lot longer to dull. The main benefit of carbide-tipped blades, however, is how fine they cut.
As for the kerf, or how wide the saw’s blade is (and therefore how much material is removed by the cut), thinner is better. A thinner kerf means less material lost, less sawdust and debris, and also helps prevent splintering.
At the end of the day you could have the best blade in the world, but it still isn’t going to cut well if it’s dull. Making sure you have a newer or recently sharpened blade will do just as much to prevent splintering as the type of blade will.
One last thing is to make sure that the blade you choose fits your saw. It doesn’t matter how well the blade cuts if you can’t use it.
2. Use Tape
You can’t change the wood fibers and how they’re structured, but you can give them some extra support to prevent bending and splintering.
Once you’ve measured and drawn your cut line, place a line of painter’s tape on either side of where the kerf will be. Painter’s tape helps keep everything in place while cutting and it pulls up without grabbing anything after.
3. Make a Zero Clearance Base
You’re probably familiar with zero clearance bases for table saws, but you can also easily make one for your circular saw.
These bases offer even more support to the edges of the kerf as you cut, helping prevent splintering.
To make the base, make a plunge cut in a piece of ⅛ inch hardboard, then cut the board around it to fit the shoe. Attach the board to the shoe with double-sided tape, and you now have a zero clearance base.
There is one important thing to note when using this – the guard on the cordless circular saw is lifted for as long as the base is attached, so for safety purposes, you’ll want to remove the base if you don’t actually need it.
4. Score the Cut Line
Use a sharp knife blade to score right down your cut line on both sides of the plywood. Instead of letting the fibers decide the point that they’ll break, you’re making the decision for them ahead of time and keeping them from bending first.
5. Place the Best Side Down
Whichever side you want showing for your DIY project, you’ll want to place that side down when you cut. Since the blade comes up through the bottom the teeth will make the cleanest cut on the bottom side.
Other Tips for Cutting Plywood
Now that you know how to cut plywood with a circular saw without splintering, these tricks will help the overall quality of your cut in other ways.
- Use a guide to make sure your cut stays straight
- Make sure the plywood is supported on all sides, or cut it on the floor with a layer of foam underneath
- Adjust your saw blade depth so that it’s ¼ inch deeper than what you’re cutting
- Always use proper safety equipment and follow proper safety procedures
If you have a table saw handy, you may want to use your circular saw to make rough cuts first and then the final cuts with the table saw.
You can employ many of the same tips for preventing splintering, but using the fence will help you make even straighter cuts.
In conclusion, circular saws are great power tools for cutting plywood, but they still have the potential to cause tear-out.
So, for how to cut plywood with a circular saw without splintering: use the right blade, support the fibers along the cut line, score it first, and make sure your finished side is down.