Twisting Luan

[MsNomer]

I know Luan is perfectly capable of twisting without any help from me, but I need to control the twist.  This is a trim piece for the van. The entire piece is a bit more than five feet long and 2.25” wide.  It needs a twist at each end to curve around and join the side 45° "crown molds ".   The twist is about 45° from the plys. This template approximates the final shape with the shaker holding down what will be the long center part.  The twisted ends will be screwed to the crown mold.



I can’t easily make a jig.  My plan is to wet the back side, force it into shape, and screw it down til it dries, then remove and paint both sides.

Any words of wisdom?

[Stwood_]

Buy some bendable ply, available at cabinets suppliers.
I know that 1/8" is available and up to 1/2". Bendable ply has all the plys running the same direction.
As an example https://www.columbiaforestproducts.com/p...g-plywood/


Water would probably destroy the glue adhesion on the laun.

[MsNomer]

Since my bend is about 45°, wouldn't the one-way of bendable actually be worse than luan's cross plys? I am concerned about the glue.

[Stwood_]

Hmmm. I wouldn't think so, as I've seen bendable ply bend pretty tight.
But it was a longer radius than what you are showing

[jteneyck]

Why not use veneer, commercial or shop sawn, and glue the layers required to get your final thickness with epoxy or plastic resin glue, even Titebond works according to some.  If you don't have a vacuum bag just wrap inner tubing or stretch wrap around the plies to hold them to the form while the glue cures.  

John

[MsNomer]

I have contemplated whether I could glue up layers of poster paper in place that would remain firm enough to serve as a template for making a form. I guess that would be paper ply, wouldn’t it.

[KyleD]

The Luan from Menards appears to be good for water exposure should you feel the need to press in a form.. I have a piece with a handle that covers a dog poop pail. Exposed edges and all. It has been continuously outside the north side of my house for at least eight years. No de-lamination. Also you could think about belt sanding off the back ply on the ends where it needs to twist. This may give it the flexibility needed to simply be twisted and installed. The twist will make the ends quite rigid with the small width of trim you are talking. Also if you are careful with where you belt sand to on the back of the board you can help define where the twist starts.

[Timberwolf]

I know Luan is perfectly capable of twisting without any help from me, but I need to control the twist.  This is a trim piece for the van. The entire piece is a bit more than five feet long and 2.25” wide.  It needs a twist at each end to curve around and join the side 45° "crown molds ".   The twist is about 45° from the plys.  This template approximates the final shape with the shaker holding down what will be the long center part.  The twisted ends will be screwed to the crown mold.



I can’t easily make a jig.  My plan is to wet the back side, force it into shape, and screw it down til it dries, then remove and paint both sides.

Any words of wisdom?

...............................
Use your heat gun to help it conform.....

[daddo]

Is this going to be exposed and the final surface?

If not, you could use a piece of plastic (Like a beware of dog sign) and heat it to form the turn, then shape wood backer strips to stiffen it and give it depth.

[MsNomer]

You guys have really helped my thinking process even though the thinking is still fuzzy.  

For one, you have forced me to realize that I absolutely cannot form this in place as originally envisaged.  That would require bending both ends at once to even be able to fasten the center.  DUH 
  I must either devise a jig for the bending outside the van or have another material or a separate piece for the ends.  

The most attractive option at this point is a separate small curved trim piece at each end of the long center piece.  It won’t be the ideal seamless look, but it will match trim pieces I’ve had to use in other troublesome places.    

Here is where it will go.  The trim piece to the left is final.  The pieces to the right are templates.  The final horizontal board on bottom will curve around to meet the left trim so that the assembly will be "boxed" and look finished when viewed from the ground.