I am planning on building a 54" diameter octagon table. The legs are going to curve up form the center to the outer edge of the top. The top will be 3/4" baltic birch ply with some fancy veneers. Do I need to run any bracing under the top to keep it from warping or sagging? There will be a 3"-4" hardwood band around the outside and a 2" skirt underneath. I have not built a table before and the base is going to push my woodworking skills so I am a bit nervous and want to get it right.
No expert here, I've only built one table (52" round).
You said you were using a skirt and a hardwood border; that sounds stable enough to me.
A picture would help.
A good joint with the joint landing on a leg piece would be best.
Veneer both sides equally (not pattern)
To keep it from being tippy
I would suggest 70% of the top or 37-38" diameter
To avoid warping, make sure that both the top and bottom are veneered.
Bill Holt said:
No expert here, I've only built one table (52" round).
You said you were using a skirt and a hardwood border; that sounds stable enough to me.
I agree.
If it's 3/4 ply, with a skirt, and the legs are flared out as support, it's going to be a pretty sturdy top.
I'm assuming the flared legs are going to be structural, so the only place it can really flex is that last bit of overhang outside the legs/skirt, which is mostly a hardwood border anyway?
In about 1970, my first husband glued two pieces of 3/4" ply to make 1.5", cut a 48" round, and put it on a center support. No skirt, etc. It has never budged.
Yes both sides will be veneered. The picture below is the base I am trying to make. The flared legs will be supporting the outer edge with no support in the middle. I was more worried about the center possibly flexing or sagging.
For the bottom curved pieces I was planning on band sawing. The large curved pieces I was going to use bent lamination using cherry. I am all ears for any suggestion on how to build.
My best advice....
Start with something easier
Sounds ruder than it is meant.
Never built one of these before? Maybe take the time to make one out poplar before committing to more expensive materials. Just a suggestion.
As for sagging in the middle, unless you're looking to do long term storage of an anvil in the middle of the table, or use it like a Coyote Ugly dance floor, I doubt you'll have issues with the middle sagging.