Solid Wood Machining

You are not logged in. [ Login ] Why log in
(NOTE: Login is not required to post)

Warping

5/13/20       
Joe Member

I have been working with wood all my life. Since the 1960's. And I have always had in my head, when you look at the end grain of a board, by the way the circles are, you can determine if it was to warp, what direction it would.

But my latest batch of wood I have gotten has gone the other way. ODD! So my question to all the smart folk here when you see wood as in the image,

"N" if it was to warp what way would it most likely warp "A" or "B"?

5/13/20       #3: Warping ...
Tom Gardiner

I would expect B. The way to remember is the rings are trying to straighten out. That is if the wood is drying after milling. The opposite is true if the wood is gaining moisture.

5/13/20       #4: Warping ...
Joe Member

That's what I always remembered thinking the grain circles want to flatten out so make a hill like "B" bit I got some that is behaving like "A" sooo odd.

Joe

5/13/20       #5: Warping ...
David R Sochar Member

Remember - wood only changes shape in response to changes in moisture in its environment.

While the terminology is anything but precise, where I am, the defect you describe is cupping. Warp has to do with curving along an edge.

5/14/20       #6: Warping ...
D Brown

It is possible that the lumber was surfaced or brought to the current thickness by removing more from one side than the other , now the moisture is not centered, maybe that is helping the cupping happen.

5/14/20       #7: Warping ...
David R Sochar Member

D Brown is right, but....

That is true only if the lumber is not dried properly. Hardwoods often have a final step in the drying schedule - called conditioning - that causes the wood to be a bit over dry on the surface, while the center comes right down to the right MC. Then the kiln operator adds some humidity to the load, putting back the water vapor that was taken in the short overdrying step.

Look up casehardening on this site and you can test some of your lumber in a few easy minutes.


View higher quality, full size image (600 X 314)

6/1/20       #8: Warping ...
Jessica  Member

Website: finecraftsmanlumber.com

Wood movement is entirely related to moisture loss or gain. Most moisture content related issues come from the lumber being too wet. But the thing to remember is lumber will swell if it's too dry.
What it comes down to is the orientation of the grain. What you have pictured below is a flat sawn board. The flat sawn surface is known in the wood science world as the tangential surface. Every flat sawn board has two tangential surfaces, with one being more tangentially orientated than the other. The surface that is more tangentially orientated is the surface that would be closest to the bark. We say the tangential surface shrinks and swells the most out of the three surfaces of wood. But because one surface is more tangential than the other, that surface will shrink or swell more than the other. This is what causes cupping.
So when lumber looses moisture, the surface that is closest to the bark will shrink more than the other. This causes the board to "cup towards the bark." This is what is depicted in image B. But if the lumber gains moisture, the more tangentially orientated face will swell more than the other, causing the board to "crown toward the bark." This is what is shown in image A.
It's true that this could be happening do to removing too much material off of one face, but only if the lumber wasn't conditioned properly. But if you have rough sawn or even S2S lumber that came through you're door looking like this, chances are it picked up moisture.

  • Post a Response to this thread
  • notify me of responses to this topic
  • To receive email notification of additions to this forum thread,
    enter your name and email address, and then click the
    "Keep Me Posted" button below.

    Please Note: If you have posted a message or response,
    do not submit this request ... you are already signed up
    to receive notification!

    Your Name:
    E-Mail Address:
    Enter the correct numbers into the field below:
     

    Date of your Birth:



    Return to top of page

    Buy & Sell Exchanges | Forums | Galleries | Site Map

    FORUM GUIDELINES: Please review the guidelines below before posting at WOODWEB's Interactive Message Boards (return to top)

  • WOODWEB is a professional industrial woodworking site. Hobbyist and homeowner woodworking questions are inappropriate.
  • Messages should be kept reasonably short and on topic, relating to the focus of the forum. Responses should relate to the original question.
  • A valid email return address must be included with each message.
  • Advertising is inappropriate. The only exceptions are the Classified Ads Exchange, Machinery Exchange, Lumber Exchange, and Job Opportunities and Services Exchange. When posting listings in these areas, review the posting instructions carefully.
  • Subject lines may be edited for length and clarity.
  • "Cross posting" is not permitted. Choose the best forum for your question, and post your question at one forum only.
  • Messages requesting private responses will be removed - Forums are designed to provide information and assistance for all of our visitors. Private response requests are appropriate at WOODWEB's Exchanges and Job Opportunities and Services.
  • Messages that accuse businesses or individuals of alleged negative actions or behavior are inappropriate since WOODWEB is unable to verify or substantiate the claims.
  • Posts with the intent of soliciting answers to surveys are not appropriate. Contact WOODWEB for more information on initiating a survey.
  • Excessive forum participation by an individual upsets the balance of a healthy forum atmosphere. Individuals who excessively post responses containing marginal content will be considered repeat forum abusers.
  • Responses that initiate or support inappropriate and off-topic discussion of general politics detract from the professional woodworking focus of WOODWEB, and will be removed.
  • Participants are encouraged to use their real name when posting. Intentionally using another persons name is prohibited, and posts of this nature will be removed at WOODWEB's discretion.
  • Comments, questions, or criticisms regarding Forum policies should be directed to WOODWEB's Systems Administrator
    (return to top).

    Carefully review your message before clicking on the "Send Message" button - you will not be able to revise the message once it has been sent.

    You will be notified of responses to the message(s) you posted via email. Be sure to enter your email address correctly.

    WOODWEB's forums are a highly regarded resource for professional woodworkers. Messages and responses that are crafted in a professional and civil manner strengthen this resource. Messages that do not reflect a professional tone reduce the value of our forums.

    Messages are inappropriate when their content: is deemed libelous in nature or is based on rumor, fails to meet basic standards of decorum, contains blatant advertising or inappropriate emphasis on self promotion (return to top).

    Libel:   Posts which defame an individual or organization, or employ a tone which can be viewed as malicious in nature. Words, pictures, or cartoons which expose a person or organization to public hatred, shame, disgrace, or ridicule, or induce an ill opinion of a person or organization, are libelous.

    Improper Decorum:   Posts which are profane, inciting, disrespectful or uncivil in tone, or maliciously worded. This also includes the venting of unsubstantiated opinions. Such messages do little to illuminate a given topic, and often have the opposite effect. Constructive criticism is acceptable (return to top).

    Advertising:   The purpose of WOODWEB Forums is to provide answers, not an advertising venue. Companies participating in a Forum discussion should provide specific answers to posted questions. WOODWEB suggests that businesses include an appropriately crafted signature in order to identify their company. A well meaning post that seems to be on-topic but contains a product reference may do your business more harm than good in the Forum environment. Forum users may perceive your references to specific products as unsolicited advertising (spam) and consciously avoid your web site or services. A well-crafted signature is an appropriate way to advertise your services that will not offend potential customers. Signatures should be limited to 4-6 lines, and may contain information that identifies the type of business you're in, your URL and email address (return to top).

    Repeated Forum Abuse: Forum participants who repeatedly fail to follow WOODWEB's Forum Guidelines may encounter difficulty when attempting to post messages.

    There are often situations when the original message asks for opinions: "What is the best widget for my type of shop?". To a certain extent, the person posting the message is responsible for including specific questions within the message. An open ended question (like the one above) invites responses that may read as sales pitches. WOODWEB suggests that companies responding to such a question provide detailed and substantive replies rather than responses that read as a one-sided product promotion. It has been WOODWEB's experience that substantive responses are held in higher regard by our readers (return to top).

    The staff of WOODWEB assume no responsibility for the accuracy, content, or outcome of any posting transmitted at WOODWEB's Message Boards. Participants should undertake the use of machinery, materials and methods discussed at WOODWEB's Message Boards after considerate evaluation, and at their own risk. WOODWEB reserves the right to delete any messages it deems inappropriate. (return to top)


  • Forum Posting Help
    Your Name The name you enter in this field will be the name that appears with your post or response (return to form).
    Your Website Personal or business website links must point to the author's website. Inappropriate links will be removed without notice, and at WOODWEB's sole discretion. WOODWEB reserves the right to delete any messages with links it deems inappropriate. (return to form)
    E-Mail Address Your e-mail address will not be publicly viewable. Forum participants will be able to contact you using a contact link (included with your post) that is substituted for your actual address. You must include a valid email address in this field. (return to form)
    Subject Subject may be edited for length and clarity. Subject lines should provide an indication of the content of your post. (return to form)
    Thread Related Link and Image Guidelines Thread Related Links posted at WOODWEB's Forums and Exchanges should point to locations that provide supporting information for the topic being discussed in the current message thread. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related Link that directs visitors to an area with inappropriate content will be removed. WOODWEB reserves the right to delete any messages with links or images it deems inappropriate. (return to form)
    Thread Related File Uploads Thread Related Files posted at WOODWEB's Forums and Exchanges should provide supporting information for the topic being discussed in the current message thread. Video Files: acceptable video formats are: .MOV .AVI .WMV .MPEG .MPG .MP4 (Image Upload Tips)   If you encounter any difficulty when uploading video files, E-mail WOODWEB for assistance. The purpose of WOODWEB Forums is to provide answers, not to serve as an advertising venue. A Thread Related File that contains inappropriate content will be removed, and uploaded files that are not directly related to the message thread will be removed. WOODWEB reserves the right to delete any messages with links, files, or images it deems inappropriate. (return to form)