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I need to cut some plywood down to size and it will require that I take it down from a 4'-wide sheet to 30" wide. This means I will need to find a saw guide that will support a steady, 8' rip from end to end. I am not finding any 8'-long guides and am wondering if I am going to have to make one out of scrap plywood. The thing is, I can't be 100% sure that it would be completely straight. It would be much better to find a guide that is built for longer rips.

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    What's wrong with this 98" guide?
    – Tester101
    Dec 28, 2012 at 13:57
  • Wow... how did I miss that? I am going to check it out. Thanks! Dec 28, 2012 at 20:56

3 Answers 3

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The factory edge on a fresh sheet of plywood is very straight. So use that.

Option 0: Snap a chalk line and cut by hand. Fine if you're doing sheathing, but not accurate enough for many other tasks.

Option 1: Use 2 sheets of plywood. Stack one on the other, offset by ~32". Use the top one as a guide to cut the bottom one.

Option 2: Make an 8' ripping guide.

You'll need the factory edge of a sheet of plywood, the full 8' long. Approximately 6" wide. Thicker is good. This will be the guide.

Also, a piece of doorskin (single-ply, 1/8" plywood) or 1/4" plywood, 8' long, approx 8" wide.

Glue & screw them together. Make sure to countersink the screws slightly.

Run your circular saw along the factory edge of the thicker piece, to cut the thin lower piece to match your saw.

Now you can put the fresh-cut edge on your material and know exactly where it will cut.

This jig is specific to the saw you used to make it.

There are many videos covering this on YouTube.

For bonus points, make it double sided (one narrow, one wide), so you can cut on either side of your circular saw.

Option 3: A guide that attaches to the saw, like the Kreg Rip-Cut

Option 4: Festool Track Saw These circular saws fit on special tracks to make straight cuts. Not only do they cut through heavy, thick wood with ease, but they cut through wallets even faster!

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    You can also buy 8' ripping guides; I have one made out of aluminum... Dec 28, 2012 at 1:48
  • I have some leftover 8' planks of plywood from a failed shelving project. I am going give one of those a try this week and will report back with my results. Dec 31, 2012 at 5:36
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    Just reporting back that the factory edge of a sheet of plywood worked great. Jan 15, 2013 at 0:47
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If you have yet to purchase the sheet, your local lumber yard or big box store will likely make a cut for you using their panel saw at no extra charge.

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    Just be aware that your local big-box store employee may not make that cut as precise as you'd like it to be. Also, there's no guarantee that their saw is actually still square (if it ever was).
    – FreeMan
    Feb 7, 2023 at 18:22
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I've cut a lot of plywood using a level clamped to the board. Perhaps you could use this as an excuse to get one of those sweet 8 foot levels.

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