Again, what delightful scraps end up on the floor of the wood shop! This time, I'll show you how I used scrap to check the accuracy of the angle of beveled edges I cut in plywood using two different methods.
Step 1: Tools
This is good for cross-cutting large pieces that are beyond the reach of a mitre saw.
I use it with a straightedge:
This is good for ripping or cross-cutting much smaller pieces using the mitre gage.
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Step 2: Circular Saw - Set the Angle
In these examples, I set the angle to 45 degrees using the bevel-cutting adjustment knob.
Power tools are no joke. Always use safety glasses and safe practices. Check this out for more tips on keeping your woodworking safe and fun: (click here).
I set a straightedge on a piece of scrap plywood and make a cut as shown.
Step 3: Make Set-up Guides for the Circular Saw
I used some scrap hardboard pieces about an inch longer than needed to reach the straightedge from the newly cut edge. I put them up against the straightedge and glued smaller pieces of hardboard underneath them up against the newly cut edge as shown.
Step 4: Use the Guides to Set Up the Straightedge for New Cuts
At this point, I'm still cutting scrap plywood to check the accuracy of my angle. I use a piece that is cut square and set the guides on the edge I want to cut, then locate my straightedge and clamp everything down. Make sure your piece overhangs your bench enough that your saw won't cut it.
Step 5: Make a Test Cut
Step 6: Check the Angle
In the first photo, I show a bundle of 1-inch (25mm) lengths of the scrap from a bevel cut (with a rubber band). Again, notice the pinwheel shape and the grain direction. This compounds the error, so I get a gap that is a multiple of the angular error. If I want to know how much error I have, I can measure the gap and divide by the number of pieces, in this case 8.
35 / 8 = 4.375
By the direction of the grain, I see I need to tip the saw an additional 4.375 degrees or so away from perpendicular. Of course that's more precise than I can measure, but you get the idea.
After I make the adjustment, I make another test cut.
In the second photo you see a bundle of scrap from a cut that is as close to 45 degrees as I expect to get.
Step 7: Cutting Beveled Edges With the Table Saw
You can also cut beveled edges with the table saw. I show a couple of examples, but unless your table saw is a Shopsmith like mine, your angle adjustment will probably look somewhat different. In any case, you can measure the accuracy of your result as explained in the earlier steps. I use the table saw for ripping and use the circular saw for cross-cutting, but you can also use a table saw for cross-cutting with a mitre gage and a big enough table for the board you want to cut.
Step 8: P.S.
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