Which way to pull a bow in a sheet good - Woodworking Talk - Woodworkers Forum
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post #1 of 4 Old 01-04-2020, 02:18 PM Thread Starter
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Which way to pull a bow in a sheet good

So I a making a router sled to flatten a slab for a small table. My base is a 2 foot by 4 foot 3/4 inch particle board sheet. I have 1 inch by 3 inch pine I am putting down the sides as a rail.(Im budgeted on my projects)

The particle has a bow in it length ways about a 1/8 inch with a level across it. My question is, does it matter if I pull the center to the rails or flip it and pull the ends to the rails? I am screwing and gluing it through the particle board to the rails.

I hope I make sense...

Thanks,
Rex

Hit Hard, hit fast and hit often -Admiral Halsey-
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post #2 of 4 Old 01-04-2020, 05:07 PM
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If your rails are stiff enough that their deflection is negligible then it doesn’t matter. Otherwise the only difference will be the direction in which the rails bend. In other words, the magnitude of the forces involved don’t change, only the direction.
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post #3 of 4 Old 01-04-2020, 07:08 PM
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Rails may not help ......

Typically, sheet goods will also have a twist. You'll be lucky if your piece is just curved/bowed in the length alone. Check the diagonal as well as the length. Also, if you have a flat surface like a granite countertop use that to check it. see if it will "rock". Winding sticks will also give you ab indication of any twist.


As to how to fix it, that's a horse of a different color. I'd probably use a Baltic Birch plywood rather than particle board. Two pieces screwed back to back may also work. Gluing generally doesn't help and it's too late then if it doesn't work.



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The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #4 of 4 Old 01-05-2020, 05:58 PM Thread Starter
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Thanks for the replying to my post, the rail pulled the bow out, it probably was more like a 1/16 after I looked at it again. My straight edge didn't show any twist in other directions.

I am pretty happy with the outcome and have flattened my first slab of red elm.


Thanks, Rex
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