Architectural Woodworking Forum

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

Grain Orientation for Circular laminations

2/27/14       
Joe Wood  Member

Website: http://woodsshop.com/

I'm going to be gluing up twenty 1/4" thick x 6" wide x 22' long pieces around this circular jig, which has a 4' radius.

it'll be tight grained wr cedar direct from the Vancouver Island mill. They'll slice all my pieces out of a single timber cut from a 3' + log.

I plan on having them cut this all plain sawn as it bends a lot easier then quarter sawn. My question is, should they cut it straight across the plain sawn timber like this drawing shows, or should they cut rift sawn?


View higher quality, full size image (800 X 600)


View higher quality, full size image (800 X 520)

2/27/14       #2: Grain Orientation for Circular lami ...
Joe Wood  Member

Website: http://woodsshop.com/

Here's a better drawing of the laminations.

seems to me that with plain sawn the grain might come apart when it bends.

with the rift sawn it would have straight grain on the faces. I don't think bending will be an issue with the 4' radius.

what grain pattern would you use for this?


View higher quality, full size image (800 X 520)

2/28/14       #3: Grain Orientation for Circular lami ...
Mick Steele

Either will work fine with the 4' radius. Make the decision based on what you want the wood to look like, or the cost of rift sawn verses plain.

2/28/14       #4: Grain Orientation for Circular lami ...
JeffD

I generally just re-saw the slices from plain sawn…..though I've only done hardwoods, not softwoods. I guess if your worried you could always make the laminations thinner and therefore easier to bend.

good luck,
JeffD

2/28/14       #5: Grain Orientation for Circular lami ...
Keith Newton

I'm going to go out on a limb here, and guess that this is your first attempt at a bending project like this, judging from your question, and the fact that you made a full round form.

I'm wondering if you are planning on trying to make this up as one unbroken circle, with no single splice point to all those layers. I have to ask how you plan to manage getting them glued and clamped, and if you have made a choice for the adhesive?

If my math is right, you should end up with a 5" thick x 6" cross section. Have you tried bending a single piece around yet, to see how much pressure that will take, then multiply by 20?

Just dropping down to 3/16" each will probably cut that by half.

Where I live, and I think it is common all across the country to ship and sell WRC green, or wet. Most wood will be twice as limber wet as when dry. Of course trying to glue wet would be foolish. The good news is that it should dry pretty quickly at that thickness.

It always helps to get good advice on these unusual projects to share what the intended use will be for this circle, so anyone offering their advice will be on the same page.

I'll wait to hear more before offering any suggestions.

2/28/14       #6: Grain Orientation for Circular lami ...
Gene Wengert-WoodDoc

When bending, quartersawn will give fewer defects. Moisture content is important...at 25% MC, the wood is more bendable. Adding heat, without drying, also helps.

2/28/14       #7: Grain Orientation for Circular lami ...
Joe Wood  Member

Website: http://woodsshop.com/

Oh I've done this about 5 times now, but with a slightly smaller form, and using 20' laminations. I've glued up 11 laminations without any major problems

http://woodsshop.com/MoonGate/HowtoBuildaMoonGate.htm

This time I'll probably glue up 10, then after it cures, another 10.

yeah the timber will still be green when it's sliced at the mill up there. I'll let it dry out a bit more.

this is a new larger form, and no, won't be bending it all the way in to a circle, it will have about a 4' wide gap at the bottom.

I plan on using TB III. This moon will have two 4x6 posts let-in to the moon, be restrained at the bottom until the posts are put into concrete footings so no chance of springback.

I think I'll go for rift sawn, or quarter if I can get it out of a 6x10 timber.

Gene, what do you mean by "Adding heat, without drying, also helps"

thanks all for the great replies and advice!


View higher quality, full size image (1000 X 650)

3/1/14       #8: Grain Orientation for Circular lami ...
JeffD

That's a nice looking product! I would have thought epoxy for outdoor use though? Have you been using TB3 all along?

JeffD

3/1/14       #9: Grain Orientation for Circular lami ...
Keith Newton

I'm with Jeff, I would certainly be using epoxy for this. I'd use vacuum bag to clamp it as well.

When I do large laminations, I measure out however many cups of resin I expect to need, then mix in however much colloidal silica to thicken it. The hardener can be measured by the mixing helper using the same cup over and over.

Rather than pouring the epoxy into a paint tray, I find it to be faster to just pour a stream ahead of the roller, as I walk down the length of the laminates. I then go back over with the roller to make sure it is all covered.

There is plenty of open time to do it in one session, using epoxy, if it isn't too stiff for you and your helpers to bend the 20 plus at once. The epoxy acts as a very good lubricant, which allows the plys to slip by each other while the bend is being made.

Rather than trying to stuff this long slippery stack of parts into a long bag, I lay out a long strip of plastic, with the dry stack on top of it. I start by pouring the epoxy on ahead of the roller, as stated above, then flip that piece over to do the other side, and just transfer the parts from one stack over to the next, doing both sides, until I'm through the whole stack.

It is already on top of the bag, so I just fold it over and seal it. I have done this just using carpet tape, which is already on one side, ready to be peeled before sealing. However, any wrinkles can cause a leak, so I always have butyl or rope caulk to mash into the wrinkles. Now, I think I would just go ahead and have a couple of caulking tubes of butyl and just go with that to stick the bag.

With a good pump, you will get 1000 pounds of clamp pressure per running foot, of perfectly even pressure, so you could get by with just two clamps at each end to hold it around the form while drawing the vacuum.

Back to your original question, I think the glue lines are less obvious on the QS, or rift edge of plain-sawn plys, than when you have the broad rings scattered across the glue lines.

3/1/14       #10: Grain Orientation for Circular lami ...
Joe Wood  Member

Website: http://woodsshop.com/

oh I've never had a problem clamping, don't need a vacuum bag, you just got to Work It around as you clamp, this one we used weldwood plastic resin glue.

not worried about springback really, you can see the temporary cleat holding it together.


View higher quality, full size image (900 X 675)


View higher quality, full size image (900 X 675)

3/11/14       #11: Grain Orientation for Circular lami ...
Jim Lewis

If you are gluing partly dried wood you won't have to worry about springback, just the opposite. The circle will tend to close as the wood dries. Think of the change in geometry and you will understand why.

You will be helped by the fat that cedar doesn't shrink very much, and that a thick section like that will take some time to dry. However, if you wait to long to install it your posts will no longer be parallel.

That said, in answer to your question, I agree. Rift will look nicer by far and neither will be a practical problem to bend.

3/12/14       #12: Grain Orientation for Circular lami ...
Dan Bloomer  Member

Website: http://www.handrailing.com

I think Joe is perfectly justified using TB III. I've used epoxy a lot and still do, but in many cases I think it's at least as prone to failure as the cross-linking or plastic resin. This may be particularly so in the case of bent laminations where there's a likelihood of heavy clamping pressure. Epoxy should not be heavily clamped at all.

3/12/14       #13: Grain Orientation for Circular lami ...
Joe Wood  Member

Website: http://woodsshop.com/

appreciate all the input fellas, I'm still waiting on my supplier to get back from BC ..

3/14/14       #14: Grain Orientation for Circular lami ...
Philip Nereo Member

Website: http://nereowoodworking.com

For exterior millwork -- especially when the wood has a higher moisture content -- We LOVE Titebond polyurethane (like goriila glue, but sands better) -- Seems to be pretty much waterproof

  • 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)