Results 1 to 15 of 15

Thread: What Glue To Use For Bent Laminations

  1. #1
    Join Date
    Sep 2006
    Location
    Northern Illinois
    Posts
    739

    What Glue To Use For Bent Laminations

    I am building a snow sled for my youngest grandchildren. I'm planning on using ash strips to make several bent wood laminations for the runners and rails. I've done some bent laminations out of cherry for a crib and know the basic process. For the crib I used Titebond 3.

    However, since this sled will be used outside in a wet environment I'm wondering if I should be using TB3? Should I go to epoxy?

    If I do use epoxy, what do you use to keep the glue from sticking to the forms? Can I line the form with packing tape, or will simply waxing the form work?
    Wood'N'Scout

  2. #2
    I have done laminations with both Titebond 3 and epoxy. Once cured, I don't know there is much difference. The Titebond 3 (when cured) will be waterproof and stronger than the wood itself. When gluing up runners or something similar, I use strips of wax paper between the wood and the form. Works well without the hassle of adhesive the you have to deal with later.

    I think your bigger issue will be the finish of the sled, because it won't matter WHAT you use for the laminations if the wood becomes saturated and starts to weaken. If it were me, I would build the sled with Titebond 3, and then finish it with a penetrating epoxy (like what you use for boats / canoes).



    Last edited by Gregory Peterson; 01-15-2014 at 10:36 AM.

  3. #3
    I have a slightly different perspective than Gregory. I think all things being equal, they are both fine adhesives, however the Tight Bond, like any glue in that class should have strong even clamping along its entire length, where epoxy is much more forgiving, just a firm contact along the mating pieces takes care of clamping. When we attach gunwales to boats or make stems, we typically only need to use spring clamps every 4 to 6 inches depending on the pressure of the curve with epoxy.

    Epoxy also has the benefit of filling the voids between the layers so you do not want so much clamping pressure that you push the epoxy out of the joint. When I glue with epoxy, I first coat each mating surface with clear epoxy, let that sit for a few minutes, and then add some wood flour to the remaining mixture and paint over the surface again.

    As far as keeping the layers separated, simply use painters tape between the layers you don't want to stick together. The picture to the left shows a canoe stem being made, you can see that there is blue painters tape on the stem form and there is tape between the 2 and 3 lamination as they will be separated when dried. Been doing it this way for 30 years and it works every time. I just use a chisel or screwdriver to pop them apart when done and then give them a sanding.
    If it is going to be outside for long periods of time (and hopefully a project like this will be), remember to put a good coat of UV protection over any epoxy.stem_glue_up.jpg
    Jackbat

  4. #4
    I should change my user name to Greg_P. Only my mom calls me Gregory

    The only comment I would make is about the painters tape. I find when I clamp painters tape it leaves adhesive behind. The wax paper works better for me. Then again, I am probably clamping harder than you are so it may just depend on the application. Because I am building custom furniture I can't have even the slightest gap showing in any of my joints so I really make it tight.

  5. #5
    You are absolutely right Greg about the tape leaving a residue behind. I always give a quick sanding when done. Wax paper is a better way to go, my problem has always been keeping the layer of loose separator like wax paper from moving around while I am clamping. Pretty much all of my bends are 90 degrees or more and at least 50" long. Between the layers of lamination, wax paper slipping off my form and a cup of rapidly curing epoxy I find that I am simply not as nimble as I used to be.
    I am definitely open to new ideas if you have a special trick to keeping the paper in place.
    Jackbat

  6. #6
    Join Date
    Aug 2008
    Location
    Southern California
    Posts
    179
    I used Unibond 800 for my bent laminations and a skateboard vacuum press for my Morris chair back slats. Spring back was minimal. It worked out quite well for me. A thin epoxy should be a good choice too.
    IMG_0905.jpgIMG_0932.jpgIMG_4946.jpg

  7. #7
    Join Date
    Dec 2010
    Location
    Evanston, IL
    Posts
    1,424
    +1 on Unibond 800 if preventing creep over the long term is an issue. I don't know if it would be on a toboggan; I recall the toboggans I rode as a kid all had chains that supported the bend.

  8. #8
    OK, now I want to build a toboggan, thanks Steve. Broke my first bone on a toboggan, ah, good times.

    And yes, there was a chain that wend from the end of the bend to the deck of the riding surface if memory serves.
    Jackbat

  9. #9
    Join Date
    Oct 2013
    Location
    Attica, OH
    Posts
    86
    This is a timely post. I found an old toboggan plan that ran in Popular Mechanics and plan to build a couple down the road.

    Jack, in that canoe stem photo, how many layers of wood are in each piece? Or are they just single pieces that have been steamed?

  10. #10
    That particular boat has two laminations on the inner stem and two inner laminations on the outer stem for a total of 4. so what you see there is 4 each of 1/4" X 3/4" pieces of Ash which were steamed and bent around the form with a piece of painters tape between the two upper and two lower. When you steam like that you need to give them a day to dry out before applying epoxy to them. So after a day to dry, just back off the clamps, apply the epoxy and put the clamps back on.

    If you don't have a steamer, you can just build a box out of plywood with dowels through the sides to create a platform to get the wood slats up off the bottom of the box and use a Wall Paper steamer to supply the steam. Less than a hundred bucks if you have to buy everything.

    You bring up a good point though, there are companies which like to use cold laminating techniques instead of the way that we do it. For many things it works fine. In fact we use that technique for making coamings for kayaks. I wouldn't do that here though. Remember that epoxy is a brittle substance, so using lots of thin pieces cold bent and laminated will be a much more brittle finished product than just a couple of steamed and bent pieces. For stationary objects this isn't a big deal, but for a sled which will be taking a pounding I would stay away from that technique.
    Jackbat

  11. #11
    Join Date
    Sep 2012
    Location
    Wapakoneta,Ohio
    Posts
    427
    What about polyurethane glue,is that a good glue for curved work?

  12. #12
    Join Date
    Oct 2008
    Location
    Webster Groves, MO
    Posts
    261
    I don't think I'd rely 100% on glue but would add some mechanical fasteners and plug the holes to hide them or use dowels in a contrasting wood.

  13. #13
    Max, Polyurethane is great for holding (especially if you read the instructions on how to use it correctly), but it leaves some pretty unsightly joints. I use it when clamping is particularly difficult and the joint won't bee seen.

    @ Stephen, if properly applied, the epoxy joint will most definitely be stronger than the wood itself. Just about every time we make laminations here, I take the cutoffs and beat them with a hammer to try to break them. I have never cleanly broken the epoxy joint without taking wood. The deeper the epoxy penetrates the wood, the stronger the joint. That is why I avoid doing laminations using fast hardener, use clear epoxy on surfaces before using thickened epoxy, and don't make laminations in a cold shop as it will reduce the viscosity of the epoxy mixture. If you are working in an unheated shop, get yourself a hot pot of water (from the tap), and set the cup of resin (without the hardener) and hardener (without the resin) in it for a few minutes to warm it up before adding them together. You can thin them out chemically but that will weaken the strength of the epoxy and it typically only done for saturation coats or barrier coats.
    Jackbat

  14. #14
    Quote Originally Posted by Jack Battersby View Post
    The deeper the epoxy penetrates the wood, the stronger the joint.
    This is an important point - particularly if you are using hard wood with tight grain, or working with wood with higher moisture content. I use thin epoxy always with wood - I find the normal store-bought epoxy "cement" to be much too thick.

    If you are looking for a good source for marine grade epoxy, I recommend this company. I have used them in the past for numerous applications, and their product works - plus they have great customer service.

  15. #15
    Join Date
    Oct 2008
    Location
    Webster Groves, MO
    Posts
    261
    Sorry, I read it wrong - I was thinking of the actual joinery of the toboggan - didn't realize it was only about the bent lamination.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •