Plywood can be a bummer can’t it? The chip out/tear out on it is horrible at times. The reason why is because of the veneered layers. I worked at a plywood mill for about 7 years, and when I moved to the glue line, I had a hand in layering the plywood. The top layer on most construction grade plywood, even A and B grade is going to be only 3/16 of an inch at its thickest. But it will also go down to 1/8 on the other side of the sheet.
The results? Disaster when cutting this thin veneer on the table saw. Even though it is laminated with layers, those top layers love to chip. One reason this is worse with construction grade plywood than it used to be is because they make the plywood from hybrid pine. I worked on the green end where they peeled the plywood on these gigantic lathes, and when they started growing and peeling the hybrid pines, they had to reconfigure the lathes. Why is that?
Because the hybrid pine is so soft and weak in comparison to the virgin timber that it would just fall to pieces when they ran it on the original equipment. But even with great hardwoods, you can have an issue with the plywood. So here are some tips to cutting it:
1. Setting Blade Height Properly
When the goal is making clean, consistent cuts in plywood, most tablesaws need a height adjustment to deliver good results. Of course, low blade height is a good habit, as it encourages safety with most jobs. The problem with using a low height setting on plywood is that it cuts through just a few plies at a time. This weakens the plywood’s structure without breaking it and produces rough cuts. Adding a few inches to the blade’s height will produce much cleaner cuts. This way, the saw’s teeth are more or less vertical when they reach the plywood, cutting through the veneer on the face and structural core at the same time.
2. Use A Good Table Saw Insert
A normal insert plate for tablesaws isn’t ideally suited to cutting plywood. A better option is to install an insert with zero clearance; this will sharply reduce (and possibly even eliminate) chipping on the plywood’s lower face. When the blade meets an insert like this, it cuts an opening matching its thickness. This provides complete support to the plywood right up to the edges of the cut. Virtually all saw manufacturers produce zero-clearance inserts for their tools.
3. Score Before And During Cutting
When you plan on leaving both sides of a cut piece of plywood exposed, you’ll want to avoid chipping either side. Scoring passes are the technique you need to master to accomplish this. You should lower the blade down to an eighth of an inch (or even a sixteenth) to make your scoring cuts. Raise the blade per the first tip when it’s time to finish off your cut.
4. Use The Right Blade
Blade selection plays a big role in overall cut quality. Most tablesaws are fitted with combination blades. These perform very well when they’re used at low speed and kept sharp, but for intensive plywood work you can do better. A blade designed to cut sheet stock (featuring 80 teeth or more) will deliver better results. Sheet good blades reduce chipping by cutting in smaller increments, and their teeth have bevels designed to score veneer as they cut. Although these blades need an even slower rate of feed, the results are well worth a little patience.
With handheld saws, the default blade is usually designed for rough cuts on construction-grade lumber. Invest in a plywood-specific blade with carbide tips instead. For an economical alternative, you can also use disposable blades (thin-kerf steel) for smaller jobs.
5. The Last Word In Clean Edges (For This Part)
Sometimes a particular cut defies all attempts and refuses to come out clean. Don’t worry, there’s one final solution. What you need to do is use oversize cuts, leaving yourself a margin of 1/8″ to 1/16″ beyond your finish edge. Attacking this rough edge with a router (using a pattern bit with bearing guidance) and a straightedge will produce the sought-after clean edge.
Keep reading to learn more great tips with the next article!
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Ted Leger –
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