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Thread: Maple bowed after planing

  1. #1
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    Maple bowed after planing

    I was milling down some 4/4 maple to 1/2 and ended up with some bowing in the wood after planing. I am a novice so I'm trying to troubleshoot where I went wrong with my process. The maple has been in my garage/shop for a couple of months now though hasn't been touched until today. I started by rough cutting the maple to 26" and then ran it through the jointer which only needed a few passes to get a flat face and square edge. I then ran it a bunch through the Dewalt lunchbox planer to get it to final size and unfortunately only noticed the bowing at the end.

    In doing some reading after the fact it sounds like planing so quickly after jointing could be contributing to the bowing. I also removed the majority of the material from one side of the board which also sounds like a mistake. I'm also wondering if taking 50% of the wood off could be another factor. Thoughts?

  2. #2
    I think removing most of the wood from one side is the cause. Best to look at the board after each pass, then remove
    wood from the convex side.

  3. #3
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    I normally joint, then leave the wood for a couple of days on edge on the bench.

    If the wood is still straight I then plane it, and as Mel indicated I try to remove similar amounts from both faces....Rod.

  4. #4
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    If it's an issue of uneven moisture content in the wood they might straighten up some in a few days. If it is release of internal tension in the wood they probably won't, or will even continue to bend. Equal removal from both sides is the rule of thumb, but doesn't always solve the problem. I don't wait between jointing and planing, but if I have time, I will wait after resawing a board to see what it does. If having the boards stay dead flat is critical you'll have more success if you choose quartersawn (vertical grain) boards for those components.

    Some boards just seem prone to bowing; trying to force them to stay put is just an exercise in frustration. Even if they are flat one day they are not the next. Best to relegate those to an application where it doesn't much matter.

  5. #5
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    Guys above got it.

    Best bet is to do a rough mill first equally on both sides, sticker the wood so it can breathe for a week or so, then final mill on both sides and keeping it stickered in between days in the shop.

  6. #6
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    Quote Originally Posted by Matt Day View Post
    Guys above got it.

    Best bet is to do a rough mill first equally on both sides, sticker the wood so it can breathe for a week or so, then final mill on both sides and keeping it stickered in between days in the shop.
    +1. I also add a little weight on top of the stack to help keep the top most boards straight.
    Brian

    "Any intelligent fool can make things bigger or more complicated...it takes a touch of genius and a lot of courage to move in the opposite direction." - E.F. Schumacher

  7. #7
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    Quote Originally Posted by Mel Fulks View Post
    I think removing most of the wood from one side is the cause. Best to look at the board after each pass, then remove
    wood from the convex side.
    This. Always. Bowing/cupping after milling is most often because of uneven moisture resulting from taking off a lot more wood from one side of a board than of the other. It's good to get in the habit of flipping for each pass, keeping the "show face", if that applies as your last pass. IMHO, of course.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #8
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    Quote Originally Posted by Jim Becker View Post
    This. Always. Bowing/cupping after milling is most often because of uneven moisture resulting from taking off a lot more wood from one side of a board than of the other. It's good to get in the habit of flipping for each pass, keeping the "show face", if that applies as your last pass. IMHO, of course.
    That makes total sense and thankfully I didn't mill everything in one go so I can still course correct. Does the amount taken off relative to the overall thickness of the starting board matter in your opinion?

  9. #9
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    Quote Originally Posted by Mel Fulks View Post
    I think removing most of the wood from one side is the cause. Best to look at the board after each pass, then remove
    wood from the convex side.
    I need to add that to my flow and make it a habit. Does it matter if I need to do a number of passes before that side is flat and parallel with my jointed face?

  10. #10
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    Quote Originally Posted by roger wiegand View Post
    If it's an issue of uneven moisture content in the wood they might straighten up some in a few days. If it is release of internal tension in the wood they probably won't, or will even continue to bend. Equal removal from both sides is the rule of thumb, but doesn't always solve the problem. I don't wait between jointing and planing, but if I have time, I will wait after resawing a board to see what it does. If having the boards stay dead flat is critical you'll have more success if you choose quartersawn (vertical grain) boards for those components.

    Some boards just seem prone to bowing; trying to force them to stay put is just an exercise in frustration. Even if they are flat one day they are not the next. Best to relegate those to an application where it doesn't much matter.
    Is there any way to gauge the internal tension prior to milling? I was caught off guard because the board was more straight prior to milling. Granted the faces were rough but it wasn't bowed like it had at the end.

  11. #11
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    Quote Originally Posted by Matt Day View Post
    Guys above got it.

    Best bet is to do a rough mill first equally on both sides, sticker the wood so it can breathe for a week or so, then final mill on both sides and keeping it stickered in between days in the shop.

    I agree, but this really is a viable option only for hobbiests. No commercial shop could afford it. I'm a hobbiest, too, for the most part, but I'm too impatient to wait several days between processing wood for a project; just not in my DNA. I've found that if your stock is at EMC with your shop it stays flat after jointing, no matter how much you take off each side. The exception is reaction wood, but that's a different animal. I'm lucky in that the RH in my shop is reasonably well controlled and changes slowly. Wood stored in my shop is always close to EMC and I have very few problems with wood bowing after jointing or planing. Nevertheless, I never joint one side and then let it sit. If there is a difference in the RH vs. MC of the wood that would cause it to bow. IMHO, it's better to joint and plane in one process, whether or not you bring it to final thickness or can afford to sticker it and wait a few days.

    John

  12. #12
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    Quote Originally Posted by Gabriel Marusic View Post
    That makes total sense and thankfully I didn't mill everything in one go so I can still course correct. Does the amount taken off relative to the overall thickness of the starting board matter in your opinion?
    It can matter in the sense of moisture content...depending on the specific board. I've had boards that scan with a meter at an acceptable MC from the outside, but once the faces are taken off, the numbers are very different. Now that's usually thicker stuff obviously, but even 4/4 material "can" have an imbalance. So other than some special cases where the exposed figure on one side is more important than the risk involved with asymmetrical thicknessing, I always try to be as even-handed as possible when reducing thickness.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  13. #13
    Hi Gabriel,

    I'm assuming the piece of maple you have is Flatsawn? A good majority of the maple out there is not Quarter Sawn, so it's tougher to keep straight. Cutting it down 50% to around a 1/2 inch is pretty thin.

    Taking some of each side may have helped. But then again, even if you did, a relatively thin 1/2" thick piece of maple will probably not stay straight for very long.

    Especially if it's flatsawn maple.

  14. #14
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    Quote Originally Posted by Robert London View Post
    Hi Gabriel,

    I'm assuming the piece of maple you have is Flatsawn? A good majority of the maple out there is not Quarter Sawn, so it's tougher to keep straight. Cutting it down 50% to around a 1/2 inch is pretty thin.

    Taking some of each side may have helped. But then again, even if you did, a relatively thin 1/2" thick piece of maple will probably not stay straight for very long.

    Especially if it's flatsawn maple.
    It is flat sawn maple. I'm using it to make drawer boxes, take it my wood choice wasn't the best for the task at hand?

  15. #15
    You don't use the "best stuff" for drawer boxes. Using "secondary woods" enhances the beauty and perceived value
    of the cabinet woods.

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