Eric Definately Keep the plywood for a solid base, attach the your Edge strip with Glue & Biscuits to the top only If you are concerned about the differance of expansion and contraction Then Glue the mahogany down to the ply with silicone. Apply spots of slicone about every 12" in each direction let the weight of the Mah. top settle on the silicone. Make sure you finish the back side of the Bar top with the same material as the topside. You can apply a few screws to keep the top from creeping while the silicone sets up. Or you can use tape. Do not use clamps and if you use the screws don't set them down tight. This is the tryed and true method of preventing problems from the differance's of movement from differant materials.
Good Luck George
I've got a couple of questions regarding attaching a bar top I recently made
> out of mahogany.
>
> The old bartop is 3/4" ply with formica glued to the top. I removed all the
> formica so now there is just the 3/4" ply. Should I attach the top to the
> existing top with screws (the new top is 3/4" thick) but cut slots in the
> ply to allow for expansion? I would prefer to keep the ply to make the top
> seem more solid. I thought about gluing it down but I'm afraid that the
> solid top would try to expand/contract and eventually come loose or worse
> yet end up cracking.
>
> For the edging I am making a 2 x 1 1/2" rail and rounding over the edges
> 1/4". I think I'll have the rounded over part protrude above the bar top to
> create a 1/4" ledge around the bar. I'm worried though that there won't be
> a strong enough joint between the edge of the top and this rail with just
> glue. I could put biscuits in but I'm worried it still not be
> enough(especially if the top is only 3/4" - goes back to having the plywood
> substrate which would get 1 1/2" of glue area for rail to attach to). >
> Any thoughts/opinions?
>
> thanks,
>
> Eric
>
>