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Re: [MedievalSawdust] Unmedievally OT: Wood glue strengths, and woodworking links

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  • AlbionWood
    More detail needed about the joints: ... Nothing glues well on end-grain, so no surprise if those failed. Cross-grain can hold, if they are well-made. GG is
    Message 1 of 5 , May 5, 2011
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      More detail needed about the joints:

      On 5/4/2011 9:15 PM, Broom wrote:
      > These were end/long-grain and
      > cross-grain joints.

      Nothing glues well on end-grain, so no surprise if those failed.
      Cross-grain can hold, if they are well-made.

      GG is brittle and in my experience does tend to fail under shock loads.
      I gave up on it, and its much poorer-quality imitator from Franklin,
      when I started having to repair long-grain edge-joints that broke
      cleanly along the glueline. I think this is a case where the test
      procedure fails to reveal the true weakness.

      You also mentioned that you had to clean up squeeze-out on "most" of the
      joints. GG and the other expanding PS glues should ALWAYS make a big
      squeeze-out mess; if there isn't a significant and continuous bead of
      foam on both edges of the join, you had a bad joint. (Side note: Never
      try to wipe off the excess, you'll only make a worse mess. Wait for it
      to cure and you can just pop it right off with a chisel. This is also
      true for yellow glue.)

      Better luck,
      Tim
    • Kean Gryffyth
      I ve not had good luck with Gorilla Glue. I stick to Titebond III, unless I m working in a particularly dark wood, in which case I ll use Titebond II for dark
      Message 2 of 5 , May 5, 2011
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        I've not had good luck with Gorilla Glue. I stick to Titebond III,
        unless I'm working in a particularly dark wood, in which case I'll use
        Titebond II for dark wood.

        -Kean

        On 5/5/2011 12:15 AM, Broom wrote:
        > So, I'm building some cabinets, and tried to join them with Gorilla
        > glue, hoping to simplify the process of assembly. Ignore the sense of
        > that first idea, and let's get straight to the results...
        >
        > Some of the joints failed with minimal stress (moderate handling).
        > Others seemed stronger, but I didn't give them a real shakedown. I've
        > decided to back up all glued joint with brads. However, I was left
        > wondering what went wrong...
        >
        > This site:
        > http://woodgears.ca/joint_strength/glue.html
        > ... reinforces the manufacturer's claims that Gorilla glue is very
        > strong. The author suggests that Titebond 3 is the strongest glue of
        > all, but the single-test failure differences are actually rather
        > slight for the "first-tier" glues (Hot glue, Epoxy, and "Varnish as
        > glue" were noticeably weaker).
        >
        > Nonetheless, I had joints fail when dropped a few inches onto cement,
        > all on the glue line (no wood failure). These were end/long-grain and
        > cross-grain joints. The joints were clamped for the recommended 30
        > minutes (usually much longer), and cured for the recommended 24 hrs.
        > The failure was from shock, not sheer force (the above webpage only
        > tests sheer failures).
        >
        > So, any clues what went wrong?
        > * Expanding polyurethane may be very sensitive to shock. Like glass,
        > it may be strong, but brittle.
        > * Maybe I didn't have enough glue. (But good lord, I tried! And had to
        > clean most joints of excess.)
        > * The garage was cool; this slows cure times. However, this wouldn't
        > explain why some joints were strong and others weak.
        >
        > --
        >
        > Someone recently asked for woodworking blog links, This site is pretty
        > fascinating.
        > http://woodgears.ca/links.html
        >
        > ' | Broom IAmBroom @ gmail . com
        > ' | cellphone: 412-389-1997
        > ' | 9370 Shadduck Rd, McKean, PA 16426
        > '\|/ "Discere et docere", which means:
        > '/|\ "We see with our eyes only to the degree that we use journalists
        > //|\\ to read our newspapers."
      • Alex Haugland
        did you wet mating surfaces? the urethane glues rely on moisture to cure properly... --Alysaundre Weldon Barony of Adiantum Kingdom of An Tir
        Message 3 of 5 , May 5, 2011
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          did you wet mating surfaces?  the urethane glues rely on moisture to cure properly...

          --Alysaundre Weldon
          Barony of Adiantum
          Kingdom of An Tir



          On May 5, 2011, at 4:37 PM, Kean Gryffyth <kad.dsl@...> wrote:

           

          I've not had good luck with Gorilla Glue. I stick to Titebond III,
          unless I'm working in a particularly dark wood, in which case I'll use
          Titebond II for dark wood.

          -Kean

          On 5/5/2011 12:15 AM, Broom wrote:
          > So, I'm building some cabinets, and tried to join them with Gorilla
          > glue, hoping to simplify the process of assembly. Ignore the sense of
          > that first idea, and let's get straight to the results...
          >
          > Some of the joints failed with minimal stress (moderate handling).
          > Others seemed stronger, but I didn't give them a real shakedown. I've
          > decided to back up all glued joint with brads. However, I was left
          > wondering what went wrong...
          >
          > This site:
          > http://woodgears.ca/joint_strength/glue.html
          > ... reinforces the manufacturer's claims that Gorilla glue is very
          > strong. The author suggests that Titebond 3 is the strongest glue of
          > all, but the single-test failure differences are actually rather
          > slight for the "first-tier" glues (Hot glue, Epoxy, and "Varnish as
          > glue" were noticeably weaker).
          >
          > Nonetheless, I had joints fail when dropped a few inches onto cement,
          > all on the glue line (no wood failure). These were end/long-grain and
          > cross-grain joints. The joints were clamped for the recommended 30
          > minutes (usually much longer), and cured for the recommended 24 hrs.
          > The failure was from shock, not sheer force (the above webpage only
          > tests sheer failures).
          >
          > So, any clues what went wrong?
          > * Expanding polyurethane may be very sensitive to shock. Like glass,
          > it may be strong, but brittle.
          > * Maybe I didn't have enough glue. (But good lord, I tried! And had to
          > clean most joints of excess.)
          > * The garage was cool; this slows cure times. However, this wouldn't
          > explain why some joints were strong and others weak.
          >
          > --
          >
          > Someone recently asked for woodworking blog links, This site is pretty
          > fascinating.
          > http://woodgears.ca/links.html
          >
          > ' | Broom IAmBroom @ gmail . com
          > ' | cellphone: 412-389-1997
          > ' | 9370 Shadduck Rd, McKean, PA 16426
          > '\|/ "Discere et docere", which means:
          > '/|\ "We see with our eyes only to the degree that we use journalists
          > //|\\ to read our newspapers."

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