Getting 1/4 plywood to bend on a 2' Radi - Woodworking Talk - Woodworkers Forum
 
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post #1 of 9 Old 10-17-2009, 11:48 PM Thread Starter
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Getting 1/4 plywood to bend on a 2' Radi

I am working on an island for my kitchen which has a 2' radi. My plan is to frame it out (2x4 @ 6"OC), put down 1/4 plywood ,and then glue a veneer to it. The warping of the plywood is a problem. Any suggesions.....
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post #2 of 9 Old 10-17-2009, 11:54 PM
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That tight a bend is not going to happen with regular
ply. I think the have a bendable ply??

I would build a jig and glue up the end in 1 by's.
Sand it fair and cover with vernier.


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post #3 of 9 Old 10-18-2009, 04:37 AM
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Regular 1/4" plywood will not bend without doing a bit of machining first. With the grain in a vertical direction on the face, make saw cuts (kerf cuts) to the back side also vertically. The cuts have to be deep enough (just to the first ply), and spaced just enough to allow the bending radius.

To know what the spacing will be, make a test piece and make the cuts starting at 1" apart. The closer the cuts are to each other, the tighter of a bend you can get. If they are too far apart, you will have flat spots on the face. On thicker plywoods 1/2" to 3/4" the depth of cuts and their spacing will determine how easy and freely they will curve without flat spotting on the face.

If you are going to veneer the face, the ply can be glued to standing forms that are set up on the curve you want.

The easiest way to do curved plywood is just to buy "bending plywood". It is made with the plys in one direction to allow it to be curved. Usual thicknesses are 1/4" to 3/8". Some distributors carry thicker stock.

This residential bar has a curved front done with bending ply. The main face is a gradual curve and the sides are very tight. You can see the forming braces laid out on the radius used to glue up the plywood. This section is one of the soffit sections.
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This is what the bending ply looks like before being veneered.
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This is a standing end showing the height of the curve. The plywood has been veneered and dyed.
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This is the finished look.









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post #4 of 9 Old 10-18-2009, 06:08 AM
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Now that is a FANTASTIC looking piece of work!

George
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post #5 of 9 Old 10-18-2009, 06:25 AM
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Use bendable luan or bendable MDF. Chuck the 2 x 4s. They are extra weight and bulk that are not necessary and will probably weaken the structure. This can all be done with plywood and glue blocks.

Tony B Retired woodworker, among other things.


"Strive for excellence and settle for completion" Tony B
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post #6 of 9 Old 10-18-2009, 06:39 AM
where's my table saw?
 
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C Man, Beatiful Work

The design is interesting too. Who designed it?
I have A question: On the curved lower face the Omega molding obviously has to have a plan view curve to fit. How did you do that?
A curved curve...Woah! Can't get my brain around that process.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #7 of 9 Old 10-18-2009, 06:42 AM
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Thumbs up

That's impressive work Cabinetman!

Last edited by knotscott; 10-18-2009 at 06:47 AM.
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post #8 of 9 Old 10-18-2009, 07:06 AM
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Quote:
Originally Posted by woodnthings View Post
The design is interesting too. Who designed it?
I have A question: On the curved lower face the Omega molding obviously has to have a plan view curve to fit. How did you do that?
A curved curve...Woah! Can't get my brain around that process.

I don't want to hijack this thread, but the answer to this may be of some help. The moulding on the front had to be removable to do the veneer work, and add the hammered copper field trim below. In order to do that, it had to fit the plane of the front both in a lateral curve while maintaining its shape.

The process for that I've posted before. Here it is again:

This is a procedure to make curved moulding, that is of any profile. If what you want is larger or longer than the solid stock you have, or it's too much to make it out of solid stock, this might work for you. I came up with this method many years ago out of necessity, with excellent results. The idea with this is you will be needing two (2) lengths of identical moulding "A" and "B", to make curved piece "C". Keep in mind this is a lamination method and the final moulding will have varied grain due to it being laminated from two different pieces of wood.

As you see in the drawings, "C" is cut to be glued up and installed along its left side. You can start with buying two identical pieces of moulding or make them. The drawings for this explanation are segmented into 1/8" sections, to facilitate the use of an 1/8" kerf cut. Most woods will bend well in 1/8" thickness. Each segment of "A" and "B" represent a "save" or "saw kerf".

The cross hatched segments represent a "saw kerf". So, after slicing on the TS the segments of both "A" and "B", you will save the segments "a" from "B", "b" from "A", "c" from "B", "d" from "A", etc, for the rest of the profile.

When you have the "saved" segments they will get glued up to form "C" moulding. They can be glued up and clamped all at once or a few at a time. It's imperative to align the moulding up so the profile will be consistant.

Taller curves can be created by just vertically stacking one or more profiles, provided you have made forms for the moulding to glue to. Segments that are covered by another segment can be pin nailed if necessary.
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post #9 of 9 Old 10-18-2009, 07:25 AM
where's my table saw?
 
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Thanks C Man

Now my brain just hurts. Incredibly clever method to achieve the "curved curve". That's why they call you C Man! You Da Man! bill

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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