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Thread: Oh hey, wood moves! (Aka, don't glue things cross grain)

  1. #1
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    Oh hey, wood moves! (Aka, don't glue things cross grain)

    Hey guys.

    So, my awesome new sloyd bench, which I planed dead flat 3 months ago, is now cupping with a concave on the top.

    But, I realized the reason why, and just planing it flat isn't the solution.

    If you look at the design of sloyd benches like I built, you'll see that on the underside, there is a "width wise stretcher" attached to the underside of the bench where the leg assemblies go, to raise the leg assemblies above the vice hardware. Well, I glued those on cross-grain, like an idiot. You can imagine what happens as winter comes and the humidity drops off drastically: the width wise stretchers don't shrink, staying the same length, but the width of the bench (long grain) shrinks. Because the top of the bench is able to shrink in width, and the bottom is not (glued to the long grain stretchers) the entire bench top, over 2" thick, cups! And in so doing, it even bends those stretchers along with it, meaning they've become slighly convex on the underside, which is not great for width-wise stability, allowing some potential see-saw like rack to take place.

    If I want to correct this, I need to remove my vise hardware and rip those stretchers off and replace them. Yikes.

    This doesn't just happen with this bench though. I inspected a quick and dirty benchhook I made, which I also glued cross grain. Same thing, cupping! And each end cups a different direction, because the stops are on opposite faces.

    Wood shrinks in one direction and not the other. Plan on it. We all know this, of course, and I think all of you more experienced guys don't need to hear this, but I've been doing this on and off for years now and still made these huge, and very rookie mistakes. So, to all my fellow rookies, take this seriously! You can't just overcome the power of wood with glue and fasteners and expect to tame it. It'll move however it wants to, so you had better count for that and work with that tendency rather than against it.

  2. #2
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    Woodworking 101, but often ignored by the generation that learns from TV and Youtube.

  3. #3
    Yeah I'm sure older woodworkers never made the same mistakes because they just always knew better.🙄

  4. #4
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    Yea, over all a pretty crass comment. If we start to see younger people stop being interested in hand tool woodworking (fortunately, it doesn't seem we are), I know why.
    ~mike

    life in a mud hut

  5. #5
    Well…..you can get away with some things, but slabs are a totally different story.

    One of the first projects I ever made 30 years ago was a coffee table - simple design with aprons. I mounted the top using dowels all over. The darn thing never moved until my son got it and put it on his patio - the. It split in 2 places. Go figure humidor outside is much higher.

    I’ve seen plenty of antique furniture built with drawer runners glued to a side panel that are not cracked and always wonder why?

  6. #6
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    Quote Originally Posted by Richard Coers View Post
    Woodworking 101, but often ignored by the generation that learns from TV and Youtube.
    What's the issue with TV or YouTube? I have learned a lot from Roy Underhill. There are also good videos on YouTube, and there are also bad. I read lots of books, but sometimes watching how something is done is an easier reference than reading how something is done.

    I am about to turn 30 this year, and I am the only one of my friends and family that works with hand tools, let alone woodworking. YouTube, tv, books, and this forum have taught me a lot. Especially in today's world, when taking an in person class is a hard thing to do. I didn't grow up in a time when I had the benefit of learning from someone who had no choice to use hand tools and not a table saw and CNC machine.

    I appreciate that he shared his mistake, because we all make mistakes. Today on Instagram and Facebook people don't share real life experiences, they only show perfection to see how many likes they can get.

    A wise man learns from his mistakes, but the wiser man learns from others mistakes.
    Always put the crappy side against the wall

  7. #7
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    Robert, I could guess a few possibilities. The ones that crack get thrown away. The panels that survive may have been quarter sawn pieces.

    Many of the howtos found in the internet or YouTube pay little attention to taking wood movement into account in a design. The focus is on giant glue up assemblies or high precision flattening w some fancy tool.

  8. #8
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    Luke, did the plans for your bench call for the stretchers to be glued?

    Wood does move length-wise. Check out the wood database for the different rates according to species.

  9. #9
    Everything needs to be done in proper proportion to avoid the issues the OP experienced.
    Adding supports perpendicular to the grain on the underside of tables and benches is common. The problem comes when they are too small, there's not enough of them or both.
    A 2" thick top can require a lot of reinforcement if it's going to be restrained from cupping, depending on all the variables like grain orientation, relative humidity etc.

  10. #10
    I have an Armoire that I made 25 years ago that I think I made every possible wood movement mistake on. It happens to all of us at some point, usually earlier than later

  11. #11
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    Quote Originally Posted by Rafael Herrera View Post
    Luke, did the plans for your bench call for the stretchers to be glued?

    Wood does move length-wise. Check out the wood database for the different rates according to species.

    See, that's the problem. I didn't have plans.

    I was going for a Sloyd bench, which is not a popular bench to build, and for which there aren't any plans available to my knowledge.

    Even when I want to find plans on a bench, I find it extremely hard to find plans that are 1) meant for Neanderthals, and 2) actually what I want to build. The more I study old furniture or workbenches in construction and think about how to approach my own projects, the more I appreciate just how much thought goes into the traditional designs. Unfortunately, I'm always left with unanswerable questions because I never have the real pieces to inspect, only pictures to go by.

    "Filling in the missing pieces" as a novice, even an experienced novice, often results in more than a few mistakes.

    How do you guys do this? Where do you even find plans meant for Neanderthals, let alone any plans for the specific thing you want to build? I was scouring the internet looking for "Scandinavian / German / Dutch / Swedish" workbenches and couldn't even find plans for traditional, all joinery construction not using modern methods -- much less anything on Sloyd benches or turn of the century "Cabinet Maker's Benches" like these, which are what I'm interested in:


    I'd love to know the construction of the underside of this cabinet maker's bench, and how the thin board is supported or joined to the rest of the piece, as well as how that tool well and "apron" going around the sides and back are joined and constructed. I can only guess and make stuff up.

    Or this:


    EDIT: The above picture isn't appearing for some people, so here it is again:
    z-sloyd-workbench.jpg

    You can see the offending stretchers on the Sloyd bench, where the mallet and spokeshave are hanging. Guess I should have cut some sort of sliding dovetail and not glued it? Or just used a bracket or nails or something?
    Last edited by Luke Dupont; 01-27-2022 at 7:53 PM.

  12. #12
    If I got things right, what you're saying are strechers, are infact end caps?, regarding a Scandi bench.

    You might have some luck by searching for Frank Klausz workbench, many plans on google
    Here for example
    https://vdocuments.net/frank-klaus-workbench.html
    Rob Cosman has two benches should you want to see,
    https://youtu.be/DqhYuMq8_ko
    and
    https://youtu.be/U-3c5UNgDBo

  13. #13
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    Luke, I have had these books in my library for many years. I know they were reprinted in the 1970s. I didnít check but you may find them for sale on the net or may be available at your local library. They are for the most part hand tool reference books. I still get them out on occasion to help my memory. I may have done something a long time ago and have just forgotten, thatís an age related thing Iím told. I think they may be just what you are looking for.
    Jim
    Attached Images Attached Images

  14. #14
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    Quote Originally Posted by Tom Trees View Post
    If I got things right, what you're saying are strechers, are infact end caps?, regarding a Scandi bench.

    You might have some luck by searching for Frank Klausz workbench, many plans on google
    Here for example
    https://vdocuments.net/frank-klaus-workbench.html
    Rob Cosman has two benches should you want to see,
    https://youtu.be/DqhYuMq8_ko
    and
    https://youtu.be/U-3c5UNgDBo
    Thanks! I will check out the links.

    Well, in regards to the first picture, the turn of the century cabinet maker's bench, yes, the end caps and also what's underneath the bench and how the thick part at the edge attaches to the thick edge (where the dogs are) on one side and the tool well on the other (is there a vertical piece separating them? and how is that attached if at all to both the thin top and the end caps?) are unclear to me.

    But the bench I built is the second one, and the problem piece that I describe is not an end cap but rather the "raiser" for each leg assembly, again, if you look where the mallet is hanging.

    I will be using this bench as is for quite some time and probably need to do some surgery on it, but at some point I may opt to make a simplified scandinavian bench, of the type in the first picture I posted, without the complicated end vise (which is not a good use of space on a short bench anyway, and is more versatile, I feel).

  15. #15
    I only see one diagram in the post, I don't know what you're trying to compare.

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