laminating clear pine lattice

Hey Y'all!!

First post. Have a kayak project I'd like to wrap up. Hull went together just great using lumber-yard "luan" 1/4" underlay. I want to use the remainder of the scarfed "luan" ply for the deck. (One of my goals is to build this from lumber-yard stuff. I know...I'm strange that way.)

Anyhow, I'm now on my 3d attempt @ laminating curved deck-beams from the clear pine lattice sold in the molding rack. I've cut them to rough dimensions, soaked them for > 48hrs, glued them with polyurethane ("gorilla glue") and bent them over a mold.

1st attempt had significant differences in their curvature and some had twisting that made them obviously unusable. 2nd try 7 of the 10 actually straightened themselves out while drying.

Would rather not try to build a steam-box and find sawing the pieces of the molds enough of a challenge that 'sawn frame' deck beams seem even more of a challenge than laminating them. Anyone have a fool-proof method?

JohnMcC

 

That's got to be the most expensive wood imaginable.

Give the Gorilla Glue to someone you don't like.

Soaking kiln dried wood is not the way. What makes the wood bend is heat. For the sizes you need a steam box would amount to some 3/4" foam pinned together with nails and held together with duct tape or string, set on your kitchen counter with a pipe from your wife's teakettle blasting into it. Or use your BBQ grill.

Or you can use a torch to heat up a piece of pipe and keep rocking the lattice over that while applying pressure, with occasional wetting to keep the wood from scorching.

With either process, you get the wood bent to approximately what you want, and then some other time lather it up with some real glue and clamp it to a form.

Titebond glue would work for what you're doing.

 

You could use the 1/4" ply on edge (bulkhead style) for your deck frames. A single layer molded 1" and filleted will prove fairly rigid. If 1" intrudes too much, your could double them up and go 1/2" to 3/4". If you are concerned about getting the right shape, make a cardboard pattern and transfer it too the ply. Check out the frames in post #6 on this thread to see what I mean.

http://www.boatdesign.net/forums/wooden-boat-building-restoration/11-kayak-loggerhead-42099.html

I don't know what your deck curvature it, but you just might be able to laminate the ply as your were planning to laminate the lattice as another alternative.

I've done the steaming bit and it's a lot of work for what you want to do if your not already set up for it. The steaming itself is easy and I enjoy doing it. It took me several tries and evenings to get my steam box working right.

Good luck.

 

Thanks to both for your thoughts. I had a lengthy sit-and-think session in my little workshop and decided to see if the left-over scraps of luan could be persuaded to take a permanent curve, as Mr LP suggests. And if that flops, to make a steambox. This isn't my last boat (in fact, it's kind of a test-bed) and I bet I'll end up with one sooner or later anyhow.

JohnMcC

 

You don't have to heat or soak thin laminations usually. Epoxy would be the logical choice and over bending the shapes on the jib/mold by about 10% more radius will insure spring back is manageable. Also you want as many layers in the lamination as practical, which also controls spring back too.

 

I have built a few test designs using that stuff. You Must Must Must X1000 seal any exposed edge grain with multiple coats of epoxy and glass the entire exterior surface... and any interior surfaces that will see even the hint of water. If the coating is ever penetrated you must dry it as thoroughly as is absolutely possible and recoat. That stuff will rot, decay and delaminate very quickly, rendering your boat into land fill or bonfire fodder. I have two in the back right now that are waiting for the sawsall and an ignominious cessation of existence.

 

I used this method to pre-bend some gunnels in some kind of fake mahogany...meranti or luan which didn't want to do it. It worked well enough that the strips (still not on the boat...I really have to finish that thing and get it out of my dining room) still have the same sprung back shape they had two years ago.



These were simply soaked in boiling water in a PVC tube for a while then left to dry.

 

On the Tightbond glue, type II is water resistant, type III is waterproof. Type II is pretty much waterproof except for maybe constant immersion or boiling.

A handy trick with those yellow glues is they can be heat activated and also microwave activated. You can buy sheets of the dried glue or you can coat separate pieces and let them dry. I used to make curved marquetry items that were 3-7 laminations of veneer by coating all the pieces and letting them dry. I would then assemble them on the form and wrap it with elastic as a clamp and microwave it for x (Variable, it's a matter of a few minutes) amount of time , let it cool down and it was done. It can also be done with wet glue.

I've also heard of soaking wood a little, or maybe just wetting it, putting in the microwave for a few minutes and then bending to a form.

 

TiteBond II is water resistant and if wet will soften and release, if under load after considerable creep. TiteBond II passes the type 1 WBP test, but just barely and still creeps substantially (wet or dry) and softens substantial when immersed. Neither is considered a structural adhesive, so use what you will with warning.

I've bent more wood than I care to think about and PVA's aren't good for holding shapes, under these types of continuous loads (the curve wants to flatten out). You need something that will not creep, like resorcinol or epoxy. Epoxy (again) is the reasonable choice because the wood working can be fairly cruse and it still works.

If you want a wild curve, laminate it from thin "lifts" and let it sit in the mold/jig for a few days so it's good and cured. It will not spring back much if at all, depending on the number of layers in the laminate. 5 or more is desirable.

The dark red Meranti typically used, doesn't like to bend as much as other species of wood and it's wise to select a species for it's bending properties, if you have much to do.

 

John,

I just made a kayak coaming using cedar in 3/16" laminations using epoxy. The finished piece was 1.5x1.5". The spring back was 3/16" on each end.

No heat, no steam, no problem.

Mostly no problem. Be sure to extend each lamination about 2" on each end to make sure you have plenty to clamp to the tool. The last clamping point should continue the curve of the piece you are making to insure the last inch does not go straight, instead of following your desired path. Be sure and clamp across the thickness to get one side straight.

I used the Rob Macks style form for making the bend. The only problem is that this would required a form for each deck beam, unless they have a constant shape.

Lots of fiddly work, but a good result.

Par is right - Epoxy good.

Have fun.

Marc

 

I have found that a layer of 6oz cloth and epoxy on the outside of a bend of a strip of wood allows a great deal of bend to be applied.

 

A strip of sheet metal will also help a good bit, if placed on the outside of the bend during the clamping process. As with all bends, species, grain orientation, run out, etc. all will influence the success rate.