Replies

1. 
   kcg99999 | Jun 09, 2002 10:37pm | #1

   Hi Todd,

   You can’t really bend plywood. The plywood making process pretty much guarantees that the cross banding makes a stable panel that can’t be “bent” to hold a shape. Instead you can take advantage of this fact by making your own plywood, but over a curved form. When finished the plywood will be in and stay in the shape you made the form. After the plywood is made you veneer it with whatever veneer you want. This has the advantage of allowing you to take advantage of all the fancy figured veneers out there: for example, you can get mahogany in about a dozen different figures.

   The catch is that you need a vacuum bag system to do this project. But on the plus side, once you have the bag, the whole world of veneer will open to you. Veneered flat and curved panels, bent laminations, and other applications become easy using the bag.

   You make the plywood using “bending plywood” which comes in ¼” and 3/8” 4 by 8’ sheets. But that’s the easy part. The hard part is making the form. The issue is how to make a strong enough form that won’t collapse under the vacuum pressure. I make mine out of birch ply pattern routed to shape. You need enough ribs so that you have one every 4” or so. You tie the whole structure together with cross braces and then cover the form with a layer or two of 1/8” tempered masonite. I just staple and drywall screw everything together. Ease all the sharp corners so they don’t puncture the vacuum bag. You then need to cover the form with wax paper taped with packing tape so the glued up panel won’t stick to it. After the form is made I’d use two layers of 3/8” bending ply, urea resin glue and another layer of masonite on top to act as a caul. Press the whole thing in the bag.

   Once the plywood is made you veneer it using the same mold as a platen and the masonite as a top caul. When the panel is veneered, you can use the mold as a reference edge to joint the piece either with a tablesaw, using the mold as a sled, or with a flush trimming bit held in a router.

   If you need more details, see Darryl Keil’s video tape “Working in a Vacuum” available from Vacuum Pressing Systems.  My book, "Dining Tables" has some basic veneer instruction in it. 

   Hope this helps.

   Best,

   Kim Carleton Graves
   Carleton Woodworking

   
   

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   Edited 6/9/2002 3:41:46 PM ET by Kim Carleton Graves-Carleton Woodworking

1. 
   Jamie_Buxton | Jun 10, 2002 01:11am | #2

   A small tip....   It'll take lots of pieces of wax paper to cover a form as large as this.  An easier approach is to use poly drop cloths.   My local builders' store sells 8'x10' by 1 mil sheets for a buck or so.   It works well for a one-time use.   If you want to re-use it, you can buy 4 mil or 6 mil sheets for a few cents more.

2. 
   LRutherfor1 | Jun 10, 2002 03:11am | #3

   I built a jig for bending breadboard edges on table/bar tops.  I take a piece of the wood to be used for the breadboard edge and slice it 1.5 times the length of the radius needed on the bandsaw in 1/8" strips(be cafeful to keep the pieces in order).  I glue up each strip, place them in the jig, and clamp it up starting at the center and working the way to each end.  Let it dry overnight, and you'll have the radius you need.  Just cut to fit.  If you do it right, you'll never tell it it's never been cut.  I don't see why you couldn't do the same thing with a larger jig.  I'll attach a picture of a cypress bar I built using this method.

   Len (Len's Custom Woodworking)