Replies

1. 
   Jon | Feb 28, 2009 02:28am | #1

   First thing that comes to mind would be to use the "off-cut's" from the wedges you've cut (but reversed) to maintain an easier clamping situation.. Also probably the use of a "curved template of some sort at the wide portion of the wedges would serve to align the pieces. Just a thought...

   Jon

   
   

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   Edited 2/27/2009 6:30 pm by Jon

2. 
   tom77 | Feb 28, 2009 05:42pm | #2

   Greetings,

   There are issues with the solid wood approach. You may have some serious wood movement problems, depending upon the grain orientation. You should think that through. I think that a spline (or biscuits) would be effective at reinforcing the glue joint and aiding in alignment in two directions. Using the off cuts sounds good, but you may have problems with slippage, unless you can use a strap between the two cauls to prevent it. The fundamental principle in these glue ups is that the clamping force must be perpendicular to the clamped surface. Figure out a clamping arrangement for each stage that accomplishes that.

   I would personally use the veneer approach. It is not without its own challenges when doing a sunburst pattern. You must work out a process for bringing the eight pieces of veneer together at a point. I have used solid rims many times, created by piecing arc segments together. The glue joints between the circular core and the rim pieces are created by complementary routing. I usually do that first and then veneer over the core and rim. Then I can shape the rim to suit.

   Good luck, Tom.

1. 
   kngfshr | Feb 28, 2009 06:34pm | #3

   Tom, thanks for the input. I had not considered the wood movement problem. It is obviously exacerbated by the wedges being different widths along the length thereby having different amounts of movement. I think this leads me to the veneer approach. My only real concern with the idea of veneering over the rim and then routing a profile is does this create a witness line, for lack of a better term, where the veneer ends and the real wood begins?Eric

1. 
   tom77 | Feb 28, 2009 08:16pm | #4

   Eric,
   Yes, it will show a glue line. You can minimize the impact of that glue line by choosing glue with a similar color and by routing an edge feature that "hides" the line. Another tip: make the glued up assembly a little oversized to allow for edge effects and "shift" during the glue up.I just looked at a table made of maple and maple veneer, and the glue line is visible but not objectionable. On darker woods, it will be invisible.Good luck, Tom.

2. 
   DonStephan | Mar 01, 2009 09:39pm | #5

   The pattern routed onto the table edge may help hide the glue line.  My one example has a small fillet or 1/16" vertical step at the top of the edge, creating a shadow line.  I have looked at it and don't find the glue line at all objectionable.

   If you have the time, pick up a small quantity of veneer, glue to some hardwood and rout the edge.  This will give you a sample to evaluate, and allow comparing some alternatives if you so choose.

3. 
   KeithNewton | Mar 03, 2009 02:08am | #6

   I normally use veneers for this, but I will offer the suggestion of cutting your wedge parts longer than needed, if you choose to go with solid wood. If you leave ears on the large ends, with the edge of the ear parallel to the glue line, you can clamp out there where it will be cut off later.

   If you can clamp the wide end like this, you can then use a pipe clamp across the outside of several parts to close the inside, although you wouldn't be able to do 180º that way. However you could at 90º, then joining them later to make 180º should be easier after you have the first two halves joined.

   When I cut veneers, I usually cut a stack on the sled with a fresh 1/4" mdf under the stack for zero clearance, and a thick piece on top to flatten the stack. With a fine cutting blade, I usually get a very nice glue line.

   Pull a couple of parts out of the stack before cutting the final angle, so when you tape them together, you can try to make two half circles, slightly oversize. Then you can put the halves on the sled, and cut a straight line across the center line / tips, to make a perfect 180º half, which you would then tape together, if you were doing a full circle.