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Glue for Bent Laminations?

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Forum topic by CubsFan posted 11-22-2011 01:52 AM 6770 views 0 times favorited 22 replies Add to Favorites Watch
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CubsFan

26 posts in 2476 days


11-22-2011 01:52 AM

I’m working on the Morris Chair from Wood Magazine 112 ( http://www.woodmagazine.com/woodworking-plans/furniture/mission/ )

I’m to the point where I need to glue the arms to the form. My question is: what’s the best glue? I was just going to use normal Titebond II, but I was at a woodworking show this weekend where Jim Heavy from Wood Magazine was talking about bent laminations, and he recommended polyurethane glue. He likes the extended open time mostly. Now to be fair, he was talking about laminating a drawer front with 10-15 pieces, I’ve only got 3 pieces total. So open time would be slightly less of an issue for me.

Anyway, any thoughts on the best glue?

Thanks!


22 replies so far

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Loren

8296 posts in 3109 days


#1 posted 11-22-2011 03:39 AM

Yellow glue can creep from the joints. White glue is less prone to
creep but it still can. I use plastic resin glue for laminations with exposed
edges because it dries hard and won’t creep.

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a1Jim

115202 posts in 3038 days


#2 posted 11-22-2011 03:44 AM

I use resin glue also. Here’s a readily available brand.

http://www.amazon.com/00203-Weldwood-Plastic-Resin-1-Pound/dp/B001003J16

-- http://artisticwoodstudio.com Custom furniture

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DLCW

530 posts in 2116 days


#3 posted 11-22-2011 05:05 AM

I always use plastic resin glue (DAC Woodweld) on all bent lamination work. It has virtually no springback and literally welds the pieces of wood together to become one piece. Another nice feature is the really long open/working time. Upwards of 45 minutes. But you do need to keep it in clamps over night and it needs to stay warm. I use a simple electric blanket drapped over the glue up to keep it warm. You can clamp with conventional clamps or a vacuum press/clamping system. Just make sure you have good even pressure.

I get my Woodweld from my local Ace Hardware. It is a powder and gets mixed with water. Wear a mask!!!!

-- Don, Diamond Lake Custom Woodworks - http://www.dlwoodworks.com - "If you make something idiot proof, all they do is make a better idiot"

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Byron

92 posts in 1842 days


#4 posted 11-22-2011 06:50 AM

Everyone has their preferences but all glues have their problems. Resin glue requires a TON of pressure compared to yellow glue, but has more open time and less spring back. I know many many people that have had problems using resin glue. Yellow glue seems to always be a surefire glue in general applications. Any time you can use yellow glue I would recommend it, keeping in mind the benefits of the other forms of glue. Epoxy does not introduce moisture into the wood since it is not water based and when working with thin stock is usually a good idea. The downside to yellow glue besides adding moisture is how flexible it is. This flexibility causes cold creep when the layers of laminations expand at different ratios. Yellow glue is the easiest glue to work, there’s no toxic particles to mix in, and I would recommend it for normal bent laminations.

-- Byron Conn, Woodworking/Furniture Design at Rochester Institute of Technology, http://byronconn.com

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Byron

92 posts in 1842 days


#5 posted 11-22-2011 06:55 AM

After looking at this chair it seems like there’s not really a need to bend the arms, you can cut them without much if any short-grain, does not really make sense to me.

-- Byron Conn, Woodworking/Furniture Design at Rochester Institute of Technology, http://byronconn.com

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Viktor

456 posts in 2880 days


#6 posted 11-22-2011 09:03 AM

What Loren said. Titebond and such are PVA glues that creep under significant and constant load. Hide glue does not creep, but it is brittle. In practice this should not make any difference unless you are making a bow.

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rance

4245 posts in 2622 days


#7 posted 11-23-2011 01:50 AM

This is gonna sound, uh, creepy, but What is creep? I thought once you glued something, it stayed there.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

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CubsFan

26 posts in 2476 days


#8 posted 11-23-2011 01:55 AM

Thanks everyone! I’ll swing by the store tomorrow and grab some glue. Also, I second rance’s question

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Byron

92 posts in 1842 days


#9 posted 11-23-2011 02:03 AM

If you ever look at a dried glob of yellow glue you will notice it is still pretty flexible and rubbery, but when you look at resin glues and epoxies they are extremely stiff, this means that even though yellow glue gets absorbed into the grain of the wood the bond is still a flexible one, adding much strength to the joint but also allowing the joint to move slightly, so when two different pieces expand and contract at different ratios the joint is allowed slight movement. This is also something that makes epoxies and resin glues slightly less reliable due to the fact they are more brittle and can crack, Idk how much of a problem this actually creates, I don’t think I’ve been alive long enough to know for sure let alone make something that has had to face the standards of time.

-- Byron Conn, Woodworking/Furniture Design at Rochester Institute of Technology, http://byronconn.com

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a1Jim

115202 posts in 3038 days


#10 posted 11-23-2011 02:03 AM

I think of it as wood moving after being under clamp pressure. Here’s some Ideas

http://www.craftkb.com/Uwe/Forum.aspx/woodworking/41034/Glue-Creep-Was-Bent-Lamination

or better yet

http://www.adhesivestoolkit.com/Toolkits/DesignGuidance/Creep.xtp

-- http://artisticwoodstudio.com Custom furniture

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shipwright

7165 posts in 2259 days


#11 posted 11-23-2011 03:23 AM

My choice for bent lamination under pressure would be urea formaldehyde or hide glue. Either would be very strong with excellent characteristics. UF would give far more working time but does require good clamping pressure. That said, bent lamination requires good clamping pressure.

Epoxy is the wrong glue for bent lamination unless you are prepared to add a thin cloth or the like between pieces. The pressure required to compress curved laminations will drive too much glue from the joint and it will be dry. Epoxy will not function this way.

Sorry Byron, no offence intended but if you are finding epoxy brittle, you are using poor epoxy. One of the great advantages that epoxies have over polyesters is their flexibility.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

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rance

4245 posts in 2622 days


#12 posted 11-23-2011 07:34 PM

Never too old to learn. Thank you all for the explanations.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

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Nels

41 posts in 1090 days


#13 posted 12-19-2013 01:00 PM

Not to happy this morning. After gluing 2 chair backs up yesterday afternoon, I unclamped and both failed. Used Titebond III. One broke both glue joints and went back to straight boards. The other one is still curved, but one joint failed. Back to the drawing board!
The gap in the middle board is for the slats on the back of the chair.

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Hammerthumb

2532 posts in 1436 days


#14 posted 12-19-2013 11:17 PM

How thick are the pieces your laminating? Can’t really tell from the picture, but I think the pieces may have been too thick. Maybe try with thinner laminations. As far as glue, I have had real good luck with urethane glue or hide glue, depending on the project.

-- Paul, Las Vegas

View JAAune's profile (online now)

JAAune

1637 posts in 1778 days


#15 posted 12-20-2013 01:28 AM

A few tips that might help.

Use an odd number of laminations. This prevents a useless glue line in the middle that does nothing to help maintain the shape of the part.

You should be able to flex the laminations with your hands close to the shape of the form. If you can’t even come close to doing this, the laminations are too think and will be under too much stress. Make them thinner and use more pieces to get the needed thickness.

I prefer epoxy or Unibond 800 for the most critical laminations. Those that aren’t under as much stress or those that will be used in places where they are firmly held in place get glued up with Unibond 1 or Titebond III.

If using those powdered resin glues like Weldwood be sure to buy it from a place that moves a lot of product. I’m not positive but I think that’s the product only has a 1 year shelf life. If it gets much older than that it’ll cause joint failures. I’m also pretty sure the same product will go bad if the lid is left open since it will soak up moisture from the air. Get exactly what you need out of the container then shut it tightly again before proceeding to mix your glue.

-- See my work at http://remmertstudios.com and http://altaredesign.com

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