Glue for Curved Trusses

[mishle]

This is what I'm trying to accomplish

The wood is HEM-FIR

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So what type of glue titebond 3 or 2? Maybe something else?

I'm building a camper and it will only have 1/2 ply on top

 

[Guy Ashley]

The biggest issue you may encounter with Titebond is "spring back" where your curved piece will move a little.

I always use Cascamite, a urea formaldehyde powdered resin glue, but I dont think you can get that in the US, (dont think UL can be blamed for that though)!

An Epoxy resin such as the West System would be my choice.

http://www.westsystem.com/ss/

used primarily in the boat building industry and it is bomb proof!

 

[Deansocial]

jmb has been using something called soudal constuct that i hear is very strong, maybe he will chip in

 

[jmbfestool]

jmb has been using something called soudal constuct that i hear is very strong, maybe he will chip in

Love the stuff!  Best glue if u dont want to hang about and are not able to clamp (apply pressure)  as the glue holds super strong with out pressure!  BUT BUT it sets really quickly  you will only have like 4-5 mins tops! Which isnt ideal with something like doing a curve  cus by the time you have got the glue and spread it about on all the layers and get them into place and start putting the clamps on the bend it round you will be to late and it will have bonded.

Something like Titebond should be fine the more layers you have the less spring back you will get I have found out.  I did a curve with 3 layers and it didnt hold its shape any where near as  good as the 6 layer curve i did after.

JMB

 

[bruegf]

West System would be my pick.  Decent work time, especially if you float your mixing container in an ice water bath and use the slow hardener.   The ice water bath is especially helpful when mixing larger batches.

Has high strength, very good gap filling properties so clamping is not nearly as critical as with a regular wood glue, and impervious to water.

Fred

 

[peter halle]

The biggest issue you may encounter with Titebond is "spring back" where your curved piece will move a little.

I always use Cascamite, a urea formaldehyde powdered resin glue, but I dont think you can get that in the US, (dont think UL can be blamed for that though)!

An Epoxy resin such as the West System would be my choice.

http://www.westsystem.com/ss/

used primarily in the boat building industry and it is bomb proof!

You can get urea formaldehyde glue here.  It is used by woodworkers who lay up their own veneer panels.  

Here is a source for you:  http://vacupress.com/veneerglue.htm    

You might also want to check out this product:  http://www.veneersupplies.com/products/Ultra-CAT-PPR-Veneer-Glue-Size-5-lbs.html

As others have said, you need a rigid glue to minimize spring back.

Peter

 

[davee]

I've used Titebond for rocker laminates with about 10 layers and had no issue with springback.  Being a camper, I'd go with Titebond 3.  You will be interested in having enough time to get everything in place.  I'd recommend dry clamping as well to make sure you have all the spaces well clamped. Good excuse to buy just a couple more clamps as well.

 

[mishle]

 I'd recommend dry clamping as well to make sure you have all the spaces well clamped. Good excuse to buy just a couple more clamps as well.

I was thinking this very thing.

I am leaning towards Titebond 3 even though it is for non load bearing. I found out Gorilla glue the foam stuff is load bearing glue but I have had it fail to many times to trust it.

Thanks everybody for the links.

I'm still thinking on what glue to use but because I had titebond 3 on hand i did the test run as shown to to what I thought and I think more clamps

 

[mishle]

Mishle,

I'd recommend DAP Weldwood.  It will form a rigid bond and has a generous open time. CP Adhesives makes a similar product (min. 5lbs, however) if you can't find DAP locally.

Joe

I looked up the msds on the dap and it made of

01 Barium Chloride          10361-37-2  1.0-5.0 %
02 Formaldehyde              50-00-0      1.0-5.0 %
03 Urea-Formaldehyde Polymer 9011-05-6  90.0-95.0 %

What's the smell like on this? 

Researching this product I found it's what they use years ago in making lam's for airplanes.

Any one else have experience on the above product.

I took the first test of 4- 1/4 inch lams out and it sprung about 2 inches.
I noticed that I needed more clamps as I could see air gaps between each clamp.

So the next try I'm doing 7-1/4 inch lams The final ones I am going for 3.5 inches thick so 14- 1/4 inch layers
Now I have one clamp every 4 inches instead of every 8inches, I found 12 more clamps

Should I make the lams thiner would that help for strength / springiness?

 

[monte]

Unibond 800 is the only adhesive I used for curved stuff.

http://www.vacupress.com/veneerglue.htm

 

[tiralie]

Researching this product I found it's what they use years ago in making lam's for airplanes.

Any one else have experience on the above product.

I took the first test of 4- 1/4 inch lams out and it sprung about 2 inches.
I noticed that I needed more clamps as I could see air gaps between each clamp.

I used Gorilla glue on the one curved (ogee) lamination that I did. I hated it (lamination's slid all over the place) but it has held up.
I would suggest a form (bottom and top) rather than clamps on the edge.  A form allows you to put even pressure across the width and length of the curve eliminating voids or air pockets.
While there will be some bounce back it won't be as much and you won't get any voids in the lamination's. There is a way to calculate bounce back. Search on the web.

So the next try I'm doing 7-1/4 inch lams The final ones I am going for 3.5 inches thick so 14- 1/4 inch layers
Now I have one clamp every 4 inches instead of every 8inches, I found 12 more clamps

Should I make the lams thiner would that help for strength / springiness?

I used thiner laminations (3/16") but your curve doesn't look too radical.
tim

 

[jmbfestool]

Researching this product I found it's what they use years ago in making lam's for airplanes.

Any one else have experience on the above product.

I took the first test of 4- 1/4 inch lams out and it sprung about 2 inches.
I noticed that I needed more clamps as I could see air gaps between each clamp.

I used Gorilla glue on the one curved (ogee) lamination that I did. I hated it (lamination's slid all over the place) but it has held up.
I would suggest a form (bottom and top) rather than clamps on the edge.  A form allows you to put even pressure across the width and length of the curve eliminating voids or air pockets.
While there will be some bounce back it won't be as much and you won't get any voids in the lamination's. There is a way to calculate bounce back. Search on the web.

So the next try I'm doing 7-1/4 inch lams The final ones I am going for 3.5 inches thick so 14- 1/4 inch layers
Now I have one clamp every 4 inches instead of every 8inches, I found 12 more clamps

Should I make the lams thiner would that help for strength / springiness?

I used thiner laminations (3/16") but your curve doesn't look too radical.
tim

Na gorilla bond ain't the glue to use it starts to foam up and is a little thick so greater chance of not getting your joint lines tight together as well as proper messy when it starts to foam up!  

Also gorilla glue is a rip off and claim their glue is better but its no better than any other brand PU glue  it's just a brand hype.
Often placed at the till  in the tool store with a large gorilla display making you think it must be a better glue.

I agree another former is a good way to clamp the curves like Tim said.  I have done that cus I don't own many clamps and so would not be able to use the clamp method.  Also straps is an easy way to clamp your work piece back to your former as long as you don't have a flat spot the strap will apply pressure along your curve.

 

[mishle]

http://www.egcc.biz/workshop/s/springback.htm Found this for spring back.

Thanks for letting me know its out there it it's about right on to my first two tries the more layers I do the less spring back.

The first try I did to see if everything looked like I wanted I did 4 layers with a calculated spring back of 1.125 Which mine reads a little more @ 1 3/8 but I did not use enough clamps.

The second try (with double the clamps) I used 7 layers with a calculated spring back of .367 with an actual of 1/4inch

The Measurement that was not on the drawing is 18"

So next I think I will try using 3/16 with 19 layers giving me a calculation of .049861496=18/192

 

[nickao]

Hey nice little formula thanks for that!

I always thought the glue was a factor as well, I guess not.