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Thread: glueing up red oak, strength concerns

  1. #1
    Join Date
    Mar 2008
    new york city burbs

    glueing up red oak, strength concerns

    Its obvious I havent done much of this.
    Ive glued up a few small tables and a cabinet or two.
    My question, for a project coming up.
    The top of the cabinet/credenza will be approx 60 inches in length, and 20 inches wide.(I do not want oak ply, solid wood is much better on the eye)
    Will it make much of a difference if I glue up 1x4s the lengthwise, 62 inches or so, or would it be much stronger if I glued up the 20 inch length and glued that many more together?(I will rotate end grains and use bisquits)

    *there will be support under the top since there may be a small weight load on top of the credenza top.

  2. #2
    Join Date
    Apr 2007
    No, not all of SoCal is Los Angeles!
    I would prefer them glued the long way, visually. Structurally, for a credenza, I don't know that there is much concern.
    Any sufficiently advanced technology is indistinguishable from magic.
    - Arthur C. Clarke

  3. #3
    Join Date
    Dec 2006
    RETIRED(!) in Austintown, Ohio
    Glue it the long way, and don't worry about strength. The glue joint will actually be stronger than the wood itself. Unless you're parking your car on top of it, strength, and under support won't be any problem. Red oak is a very strong wood, and is one of the easier hardwoods to work with.

    Regarding alternating the grain - Don't do it! It just makes it that much harder to sand and plane it after gluing. The top isn't going to warp if it's installed properly. Besides, keeping the grain oriented in one direction makes for a much nicer looking top.

    Biscuits - not necessary. They won't add any strength to a long grain glue-up, and don't really help all that much with alignment, either.
    Jim D.

  4. #4
    Join Date
    Nov 2006
    Southern Louisiana

    not an expert here, but had a little experience with glue up. think about this. wood expands and contracts the most along its width (perpindicular to the grain). so if you glue up 16-4" x 20" strips to get your
    60", that top will probably have a tedency to grow more than if you glued up 6-4" x 60" boards to get the same top.

    also think about the appearance of the end grain, all those boards glued together, that edge would become the front of your top, unless you band it.

    the last thing is that you will find if you glue the 20" long boards, the chances of that board wanting to warp across it's width are much greater.

    hope that all makes sense.

    in the end I think visually, the 5 - 6 long boards would look better

    good luck

  5. #5
    Join Date
    Nov 2006
    Delton, Michigan

    well allen

    ya got info from some very wize folk there but i will chime in and agree whole heatedly on there advice,, have glued a fair amount of oak up and like chris said your idea of running them the short way would be no wheres close to as purty.. and i also agree with the no biscuits.. but i would suggest a caul if you can do it to help in the flatness of your top.. the shifting while gluing up and the slight differnce between the boards your using can be frustrtating and cauls would help solve that for you.. if this is one of your first large glue ups you dont want to have more headaches than nesscary... "bow clamp" makes some good cauls but you can make your own or just clamp the ends together with smaller clamps which help alot..
    If in Doubt, Build it Stout!
    One hand washes the other!
    Don't put off today till tomorrow!

  6. #6

    Good advice already. The long way. Too many wood movement concerns the other way as Chris says. Long way looks better, too, as everybody says.

    I can tell you what I would do to achieve a 60x20 top glued up from 1x4's. Get six 1x4s 6ft long. What would be even better is to get them rough-sawn (4-quarter) and surface them yourself, because surfaced 1-by is about 3/4" thick and I'll give you 20-to-1 you won't get them glued up so evenly that you won't have to take some off to get it flat. So you'll end up with a top that's less than 3/4. Which is probably okay with a credenza because you can provide enough internal support. Just saying. Why 1x4s?

    Long grain glue joints (ie, side-by-side) are very strong, as Jim says. If you bang a long grain glue joint apart it probably won't break at the glue line. Biscuits in this case are to help alignment, not strength.

    Also as Jim says, pay attention to grain direction. Two things about grain here...when you get your boards lay them out side-by-side and decide which direction they should be milled (ie, find the "uphill" direction on each board). Keep them aligned in this direction...if you don't, when you plane them after glue-up you'll wonder why some are tearing out and others aren't. After deciding that, choose the juxtapositions that afford the most pleasing affect...then mark them. You can move them around and turn them over, but don't flip them end for end.

    Will you be using a jointer to prepare the edges?...if so, keep in mind that no matter how careful you are it's not likely that you'll get the fence exactly perpendicular to the table (you'll put your Starrett square against it and think it is, but it won't be). If you joint each board such that the error accumulates you'll find that you can't slide them together and have them cozy up without a gap...then when you try to pull them together with clamps you'll have a built-in cup. The solution (well, one solution, works for me) is to figure out for any two mating boards which side goes against the fence and which direction through the jointer so that when they are side-by-side the error cancels. This will require you to joint some boards in the "wrong" direction, so keep the final pass light to minimize tearout (on the other hand the tearout is inside the joint so it doesn't matter).

    There are various ways to do this kind of a glue-up. Long ago I sprung for the Plano vertical glue press after trying many different kinds of clamps, and if you wanted mine you would have to come armed...anyway, I can't offer much here. Larry has some good suggestions. Lots of stuff on the internet about spacers to keep the boards off the glue table, alternating clamps, cauls, etc. If you do the jointer thing and use biscuits for alignment it will minimize the heart palpitations. There is no glue-up like this that is not accompanied by heart palpitations. Something I saw recently..."I don't wanna be a cabinetmaker no more...the chest pains are now five minutes apart". Consider the glue you will use, and pick one you like with a long open time. I've long used Gorilla glue mainly because of the 15-minute open time, but it does do the polyurethane ooze. On a flat surface this isn't so bad since a scraper makes quick work of cleanup (after curing). The pieces can creep on you, so watch them for about 20 minutes. Recently I've tried Titebond III and so far no complaints...less mess. I think they may be stretching their open time claim a bit though.

    Good luck. Would like to know how it turned out.


  7. #7
    Join Date
    Mar 2008
    new york city burbs
    I dont own a planer.
    If I buy rough wood, I have the lumber yard plane it for me, I pay, but I have no choice.
    I try my best to get straight ends on the tablesaw.
    I havent had much bad luck with a few short glue ups, nothing longer than 24 inches though.
    Ive already dropped the biscuit idea.

    Thanx for the comprehensive advice, I will reread all the responses a couple of times.

  8. #8
    Join Date
    Dec 2007
    Billings Missouri near Springfield Mo
    Buy your lumber hit and miss planed just to see the grain use your table saw with a good blade on it to get glue edges. Glue up the top and then find a cabinet shop with a widebelt sander to level it out for you. I see your in Long Island area and not sure what it would cost but it probably wont be much more that buying s4s lumber and trying to get a flat glue up.

    I would have charged around $20-35 to run it through mine when I had it. There time shouldn't take more that 15min to run but they may have a time minimum


    I sure miss my shop and the big boy toys

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