Large Veneered Conference Table Top
A discussion of how to lay up veneered components and assemble them for a large conference table. March 13, 2009
I have been requested to build a conference table top and despite 30 plus years in the wood working business, I have questions about how to proceed. The top is to be 6-1/2 feet wide by 13 feet long with an ovoid shape. The top will be veneered with quartersawn maple and surrounded by solid maple.
My first challenge is to figure out how to construct the substrate. Plywood laminations, frame with honeycomb, torsion box? Secondly, how do I apply the veneer? My only thought is a vacuum pump with a custom made bag. What about building this top in sections and assembling the sections on another substrate? Lastly, does anyone have any ideas on cutting the curved banding? Any and all ideas will be greatly appreciated.
(Furniture Making Forum)
From contributor V:
Send the drawings to a CNC shop and get them to cut curved jigs for the outside curve of the top, and the inside curve of the edge. Build it in two pieces 6.5x6.5 for ease of transport. A custom vacuum bag will work, but if there is a shop with a hot press close, it would be worthwhile to get them to do the actual pressing. Build the top out of particle board and double the edge up to get your thickness. Yeah, it'll be heavy, but you weren't going to move it by yourself anyway.
From contributor J:
Not so fast! 78" wide particleboard? Conference tables require meticulous engineering. You will need to figure out the base details in order to better design the top. Tables of this size are usually made with a honeycomb core - you need a torsion box construction to keep it from sagging under its own weight.
Also, you will need custom skins so that you don't have any seams in the top that could telegraph through the face veneer. These will stand out prouder than a pimple on prom night under the de rigeur high gloss finish. Think it through all the way through the finish, because it has to be a straight line!
From the original questioner:
My current plan is to re-saw solid stock quartersawn maple, edge glue these planks into 4' wide sections, wide-belt sand the sections and vacuum press those to baltic-birch plywood substrate. I would then have four sections with 1/8" thick veneer on them top and bottom. These I would then spline and edge glue together creating the large blank from which to cut the table top using CNC produced templates. Then I would glue on a 4" wide edge band of solid stock which would bridge over the glue joints of the table core. Any thoughts or critiques?
From contributor J:
If you're going to build your table this way, I have a few suggestions. Instead of pressing your re-sawn faces to the baltic birch and then joining the baltic birch, join the baltic birch and then press the faces (full width), grain perpendicular to the joint in the BB. There’s less chance for the joint to open up.
Also, double up your BB core, with the BB joints running perpendicular to one another. Be aware that 1/8" "veneer" can act more like solid wood (it's about five times as thick as sliced architectural veneer); you may see movement at the surface, where it's not constrained by the glueline. Make sure your finish can accommodate this movement.
From contributor B:
Just buy 1/16" thick veneer from Certainly Wood or some other source and save re-sawing for a smaller project. You will save time and money and the movement will not be as much of an issue. Do some decorative veneering to cover the lengths you need if they don't have what you need in stock.
From Gene Wengert, forum technical advisor:
I oftentimes get complaints about the various components being at a MC that is not suitable for interior North American environments. In other words, the wood is too wet and so it dries when exposed to an in-use environment. Make sure that you check the MC of the wood and get it to 7.0% MC. This will assure small changes, if any, in use, so the table will be stable.
From contributor O:
A little late, perhaps, but it seems implausible to me that a one-piece top made with its substrate assembled from three sections splined together along straight joints would be strong and rigid enough, even if the veneer was applied after the substrate was assembled. A furniture maker I know once built a very large and expensive dining table this way and said he could see the joint in glancing light even before the table made it to the customer's house. Since then I've often thought, though I haven't tried it, that it might be worth assembling such an oversize substrate with a zig-zag shaped joint cut with a router and template.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor T:
This is what two-ply veneer is for. Lay down a layer of "underlayment" veneer at right angles to the joint in the substrate, and then your face veneer at a 90 degree angle to this. Using the 1/16" veneer for the underlayment should eliminate any possibility of telegraphing.