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Thread: how flat is flat enough?

  1. #1
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    how flat is flat enough?

    I'm working on flattening one face of a 6' board by hand before feeding it to the thickness planer. Ultimately to be used as a table top glue up.

    I'm using a 48" (4') level as a straight edge. There is light showing in the middle of the level. Using my calipers, zeroing for the height of the level, I get 0.05" as the greatest deviation from flat.

    Would you guys keep moving iron or decide that the wood might well move more than this through the planer and call it flat enough to proceed?

    By the way, just in case there is someone in this forum that doesn't know, flattening a face by hand is hard, sweaty work!

  2. #2
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    why don't you just take a piece of plywood, place your board on the plywood, shim the voids, run it through the planer to get one side flat.

    then flip the board over runt that side through and get your desired thickness

  3. #3
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    Because I tried that before and one of my pieces ended up too bowed for use. Not sure if it was technique or movement after milling.

    Also, I've been on a bit of a hand tool buying spree lately and want to play with the new toys.

  4. #4
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    Personally, if I was within 0.05" of flat in 6' of length, I'd call it good and head to the planer. But that's just me...others with more flatwork experience might disagree.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  5. #5
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    Quote Originally Posted by Vaughn McMillan View Post
    Personally, if I was within 0.05" of flat in 6' of length, I'd call it good and head to the planer. But that's just me...others with more flatwork experience might disagree.
    0.05 is 1/20th of an inch. I'd try for about half that before heading to the planer. A well tuned #7 or #8 will take care of the problem with just a few minutes more work. Don't use a shorter plane because it'll just ride the existing contour.
    Jim D.
    Adapt, Improvise, Overcome!

  6. #6
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    Depends what that board is being used for, a stair tread, I'd not worry so much, but some things might need a bit tighter tolerances
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
    William Arthur Ward

  7. #7
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    Quote Originally Posted by Jim DeLaney View Post
    0.05 is 1/20th of an inch. I'd try for about half that before heading to the planer. A well tuned #7 or #8 will take care of the problem with just a few minutes more work. Don't use a shorter plane because it'll just ride the existing contour.
    I've been going across the grain with my #6. Thank you for the suggestion to move to the #8.

  8. #8
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    keep us in the loop mark!!!
    If in Doubt, Build it Stout!
    One hand washes the other!
    Don't put off today till tomorrow!

  9. #9
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    no matter how you flatted the board when you flip it and run it in the planner it will move again, you are removing the stress on the back side. if you want a board that is true and that will stay that way. you need to sneek up on it. i flatten with my 8" jointer then peal a little off the back with the planner and set it aside for a few days and go back to the jointer again. i will do this a few times till i get to the size i want. i then will do my glue ups. ive never had a door or table go south on me yet.

  10. #10
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    Guys if its off by 1/20" just go set down and wait about an hour or two then it will ether be right on or 1/10 of an inch off.

    Hate to be the one that tells y'all this but wood moves and cannot hold that tight of tolerance.

    Put'er thu the planer and get on with the project. :

    (DISCLAIMER)
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    A Turn N Time
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    Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you're a mile away and you have their shoes.

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