June 6, 2010

 

Veneering



     
      Veneering is a great way to maximize the use of available material and to get the continuity of pattern that is not available  using solid stock. Shop cut veneers also allows me to use local materials or other solid stock not available in veneer form. Commercial veneers, although usually sold at 1/42", offers such materials as burls, crotch, and other figured material not available as solid stock. There are some veneers sold at 1/16", although not many species are available.
     Often, I cut  veneers on my 26" Laguna band saw. A vari-tooth carbide tipped blade from Lenox assures a consistent cut, in hardwoods, even at the saws maximum throat capacity of 16".  An axillary fence helps to stabilize the material at the maximum height. Folks that come in to the shop are amazed at the thinness of the cuts. Even other woodworkers, used to standard blades are impressed with the end product.  There are ceramic blade guides helping the blade to track through the cut. Traditionally, a ball bearing  type is used, but one cannot tighten the guides enough to prevent any side to side movement. The ceramic guides do this most effectively. I primarily veneer for panels for doors and end panels. Typically I cut at 3/32". This allows plenty of stock for thicknessing and sanding.
     Once the veneers are cut or selected, the leaves need to be edge jointed. There are several steps to this. First I will straight line a bundle of leaves after having taped them together. This is a job for either the table saw or the band saw. Then I will move to the jointer to clean up the edge. Lastly I will use a No. 6 or 7  Lie-Nielsen hand plane either on its' side or upside down in a vise. For thick leaves the work is done individually, joint by joint. Edges need to match as perfectly as the material will allow, otherwise glued up panels will have exposed glue lines.
     After the joints are acceptable, I tape the backs together with blue masking tape. This tape does not adhere too strongly and having  some stretch it acts as a sot of clamp, pulling the two leaves together. I then flip the taped leaves over, tipping them into an inverted vee and apply a thin line of white glue to the edges. Laying them flat, I scrap the excess glue from the surface. Brown paper veneering tape is then applied. I use an iron to quickly dry the tape and the glue.


     With all the leaves of both sides of a  panel taped and glued, I then hinge them to the substrate. This, in my mind, is really important. Once in the press, the glue can act as a lubricant and squeeze the veneers askew. Also in the controlled hurry of gluing up a stack of panels, hinging facilitates keeping everything in order. One less portion of the process to worry about. Don't forget to remove the blue tape prior to gluing to the substrate.


      In the past I used a water based plastic resin glue from Dap, but the inclusion of water created some shrinkage and veneer curling problems. Recently, I began using Uni-bond 800, locally available from Eden Saw . This is a two part glue that works well for flat veneering and bent laminations It also comes with hardener in either white or brown. They are mixable allowing for glue that is closer in color than plastic resin, which tends to be brown to red. There is also a flexible set time depending on the amount of hardener and the ambient temperature. Measuring out the correct amounts of glue and hardener is simple using a small electronic gram scale. Mix it using a driver drill and paint mixer. I apply the glue with a foam roller.

      Two items are necessary when placing the panel in the press. First   there needs to be paper between each layer. I Use freezer pare from the local super market. This prevents the panels from being stuck together. Secondly, platens will be needed to distribute the pressure from each screw clamp. I use MDF or white melamine, both of which are flat.
      My education in veneering began with a kitchen project that was designed with all flat panels, both as doors and end and back panels. I hired another local woodworker, John Griffiths, to do the veneer work and at the same time teach me about the process. That was maybe fifteen years ago. I have since learned from other fellow wood workers from our local Woodworkers Guild.
     
            Here is the happy ending, with panels in the screw press.

   


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