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Thread: glue problem

  1. #1
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    glue problem

    I've been working on a "planter wagon". Made entirely of white oak and using Elmer's Ultimate poly glue. I became suspicious of the strength of a glue joint this morning and started looking real hard at them. Went through the scraps and cut-offs that had glue joints in them. Every one of these joints is going to fail because the glue didn't perform.

    I can go back and re-do the wagon box and seat without too much time and effort. What makes me sick is the wheels. They're done and ready for final sanding. The outer rim of the wheel was constructed using 8/4 stock and then cutting eight equal pieces to shape with the ends mitered so that when you lay all eight together you form a circle. The pieces are edge glued together with a spline in them to help me line them up during gluing. The splines were 1/4" thick which is fairly thick but won't hold that joint by itself.

    Any ideas on how to save the wheels? The front wheels are 17" in diameter, the back ones are 24" in diameter. Right now I'm thinking of making a steel rim to fit tight to the outer circumference and hope that holds the wheel together when the glue fails, but right now I'm just sick and that may not be a good solution.

    Any ideas and thoughts would be greatly appreciated. (there's four bottles of Elmer's Ultimate in my trash)
    Feel the wind and set yourself a bolder course

  2. Can you cut a curved rabbet with a router along the faces, then cut a hardwood inlay in sections that would overlap the sections of the wheel? Glued in place on both faces, that would add quite a bit of strength. In a contrasting wood it may even be a decorative element.

  3. #3
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    Polyurethane glues generally perform well unless they are either old (they have a short shelf life) or if the gap is too wide. (the foam has no strength) Further, they are usually moisture cured, so wetting one side of the joint and applying the glue to the other side is SOP with these adhesives.

    Larry, can you be more specific about what you are concerned with on your joinery with the poly glue?
    --

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

  4. #4
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    Frank, thank you, I like that idea and it's definitely possible

    Jim, the glue came from a local borg, could be old, how would you know? I don't see any kind of date stamp on the bottles.

    Gap too wide? Ah, you've seen my work. I am definitely guilty of poor joinery. However, if I take my time I can produce a tight joint and I thought I did with these wheel rims as I knew that they needed to be tight for strength and they would all be visible. I did dampen one side of the joint prior to glue up (maybe I should have dampened both sides?)

    After the wheels were assembled and glued up I cut the outer circumference on my bandsaw. That produced some offcuts which were 8/4 wide by about 1" thick at the widest. Obviously the offcuts were curved and varied in thickness. Any rate the offcuts had the joints in them which are in the wheels. Taking an offcut with about one inch of thickness I don't think I should be able to break that joint by hand. I could, every one of them, they all failed at the glue joint, not one of them broke the wood.
    Feel the wind and set yourself a bolder course

  5. #5
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    Larry, will the inside of the wheels be visible? I have an idea if they won't.


    Larry

  6. #6
    Any ideas on how to save the wheels?
    I'd sure take the glue out of the trash...it wasn't the glue. WO can be difficult to glue, but dollars to donuts it was insufficient clamping pressure.

    If you have some gaps there, poly reglues fairly well with marine epoxy, which shoulda been your first choice if the joinery isn't real tight. Poly requires tight joints, a tad of moisture, and a lot of clamping pressure....and it's very difficult to get clamping pressure circularly, that's why we use epoxy with thickener to make spars:



    You can't steam apart poly, so you're in a bit of bind here. Thin cyano will get into the gaps, but it, too needs some clamping pressure. Your best bet is to use unthickened marine epoxy and play a heat gun gently over the gaps to thin it so it seeps deep into your joints. Then I'd probably laminate a veneer "tire" to those wheel circumferences to aid in holding them together.

    The good news is that you used a glue that can be glued over. My issue with glues is rarely strength....it's usually repairability. Can its residue be successfully glued over in a repair? Nobody I know, either manufacturer or the USDA has tested that, let alone FWW....so I'm gonna play with it a bit and write an article on it.



    I focus on boatbuilding, but it certainly applies to general woodworking. If your joints can't be reglued, then your work has limited life and attendant limited value.
    Last edited by Bob Smalser; 06-25-2005 at 8:18 PM.
    “Perhaps then, you will say, ‘But where can one have a boat like that built today?’ And I will tell you that there are still some honest men who can sharpen a saw, plane, or adze...men (who) live and work in out of the way places, but that is lucky, for they can acquire materials for one third of city prices. Best, some of these gentlemen’s boatshops are in places where nothing but the occasional honk of a wild goose will distract them from their work.” -- L Francis Herreshoff

  7. #7
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    makes great sense to me Bob
    let us know the results of your "tests"
    very few of us give glue much of a thought until a problem arises.
    regards
    mike

  8. #8
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    Maybe I'm missing something, because you did say the joints were "edge glued together with a spline in them", but re-reading a couple of times I'm having a hard time seeing how this would be edge glued. The mitered joints would be 22-1/2 degrees ?? This would be at least partially end grain and you're being able to break the joint wouldn't especially surprise me. That's the reason for using the splines. I would think those should have been strong enough to hold the joint together unless the grain orientation went the wrong way - in which case those too could snap. Was the grain on the splines running perpendicular to the spline slots? Even with NO glue I would think it would be difficult to break that spline if the grain was running in the right direction.
    I know this doesn't help you fix your problem, but I'm just wondering if that's the problem and not the glue.
    Use the fence Luke

  9. #9


    The diagram makes me think of something else....end grain. If you can get the wheels apart:

    End grain ain't a gluing surface....but where there is no other choice, decent results are achieved by filling the end grain with marine epoxy using the heat gun like I described above.....then letting that epoxy cure. After curing, the epoxy is scuffed up with 100-grit and reglued using more marine epoxy.
    “Perhaps then, you will say, ‘But where can one have a boat like that built today?’ And I will tell you that there are still some honest men who can sharpen a saw, plane, or adze...men (who) live and work in out of the way places, but that is lucky, for they can acquire materials for one third of city prices. Best, some of these gentlemen’s boatshops are in places where nothing but the occasional honk of a wild goose will distract them from their work.” -- L Francis Herreshoff

  10. #10
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    Thanks for all the replies.

    Larry, yes the insides of the wheels are visible, there are spokes from the hub to the rim. Just as in Bob Smalser's last post Step 5 with the difference being my outer rim is in eight sections not four, and my splines run "vertically" through the rim and are visible both on the outer surface of the rim and the inner surface of the rim.

    Mike, you're right.

    Doug, I think the grain on the spline is oriented correctly, perpendicular to the slot. What's happening in the cutoffs I "tried for strength" is that the spline is pulling out of the slot and not breaking any wood, just looks like glue failure to me.

    Bob, yes, it is difficult to clamp a circle, and I used web clamps to do it, and I know I didn't get much clamp pressure on the joints as they were being put together. So, looks like I'm going to be giving West System some business and trying to reglue with that. I think that with Frank's idea will provide the strength I'm looking for. You didn't convince me to take the Elmer's out of the trash though.

    Thanks to all of you.
    Feel the wind and set yourself a bolder course

  11. #11
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    Quote Originally Posted by Larry Reimer
    ...
    Doug, I think the grain on the spline is oriented correctly, perpendicular to the slot. What's happening in the cutoffs I "tried for strength" is that the spline is pulling out of the slot and not breaking any wood, just looks like glue failure to me.

    Bob, yes, it is difficult to clamp a circle, and I used web clamps to do it, and I know I didn't get much clamp pressure on the joints as they were being put together....
    With that added bit of info, I'd have to agree you. Glue Failure. From your earlier description I just assumed the spline was breaking at the same point as the glue joint.

    As to clamping, the Merle clamps might be worth looking at. I've had pretty good luck using them to glue up frames. I think you can get a bit more pressure on them than the web clamps.
    http://www.mlcswoodworking.com/shops.../merlclmp.html
    Use the fence Luke

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