I’d appreciate advice on something I want to make for my dining room
ceiling. I want to make something like an oversized oval serving tray,
only the outside bottom and sides of which will be visible (painted a
particular blue). This would be an oval 36 inches by 54 inches, with
the sides about four inches high. The purpose of this is to hang three
lightweight pendant lamps from it, so those can be centered over my
dining table. The big oval is big enough to extend to an off-center
ceiling electrical box, which can’t easily be moved (concrete slab
ceiling). I’m an apartment dweller with only hand tools, a jigsaw, and
a power drill. My tentative plans:

=Plot an oval on a computer plotter, mount that lightly with spray
adhesive on the Masonite, and cut the oval out with a jigsaw, then rasp
and sand that to be as close as possible to a perfect oval. I thought
Masonite would be the easiest to make really smooth. Would thin plywood
or drywall or something else be better?

=Put a 4-inch strip of veneer around the perimeter, gluing it to blocks
spaced every few inches around the top inside perimeter of the Masonite.
These would probably be dominoes or child’s block’s from the dollar
store (something that’s already cut perfectly square). Where the veneer
strip ends join, should I put an 8-inch piece of veneer on the back side
across the joint (imagine it glue side to glue side, though veneer this
wide may not come preglued) to make sure the curve is smooth and the
ends don’t separate? Seems like I should put a bead of glue all around
the inside where the veneer meets the Masonite oval. How do I keep the
glue from seeping through to the finished bottom side?

=Run three or four ribs across the oval, glued to the dominoes and to
the Masonite. Then put a couple of stringers between each set of ribs,
also glued to the Masonite. This framework is to keep the Masonite from
sagging or corrugating. Should that be balsa or just regular 1x4s? Is
there something simpler? I thought about using the aluminum Ts used for
suspended ceilings, but couldn’t think of how to attach the Masonite.

=Fill (very little, I hope) the corners where the veneer strip joins the
Masonite, sand lightly, and paint the outside and drop the pendant
lights on cords from this platform. Then put four lead anchors in the
concrete ceiling and somehow suspend the platform (probably with
squeeze-type gate latches).

Thoughts on how to make this easier or better?

On Sat, 12 Jan 2008 21:02:17 -0600, Mr Downtown "Mr Downtown" wrote:

I’d appreciate advice on something I want to make for my dining room
ceiling. I want to make something like an oversized oval serving tray,
only the outside bottom and sides of which will be visible (painted a
particular blue). This would be an oval 36 inches by 54 inches, with
the sides about four inches high. The purpose of this is to hang three
lightweight pendant lamps from it, so those can be centered over my
dining table.

With my tools, I'd make what's called a "torsion box" from plywood.

With your tool selection, I might make this out of blue 2" thick foam
insulation board, skinned with 1/4" cabinet grade baltic birch ply and
1/8" ply or plastic laminate (countertop stuff) edges.

The oval would be cut and shaped of foam, and 4" high 1/8" thick sides
would leave 2" to hide the hardware. The 1/4" ply would be less
likely to wrinkle or ripple than hardboard. A foam safe contact
cement would attach the ply nicely. There would be scrap material
available to practice on. The only pre-paint filling would be the
joint where the 1/4" and 1/8" materials meet, and the seam in the 1/8"
strip. Bondo would fill well.

The whole thing would be light and strong.

On Sun, 13 Jan 2008 02:55:21 -0500, "Bonehenge (B A R R Y)"
wrote:

The whole thing would be light and strong.

I forgot to mention that the smooth foam edge would probably help the
edge stay smooth longer. 2" thick foam gives lots of edge for gluing
surface.

Over seasons, an edge attached to scattered points might develop flat
spots, wrinkles, and buckling.

---------------------------------------------
** http://www.bburke.com/woodworking.html **
---------------------------------------------

Id appreciate advice on something I want to make for my dining room ceiling.
I want to make something like an oversized oval serving tray, only the
outside bottom and sides of which will be visible (painted a particular
blue).

(snip)

Thoughts on how to make this easier or better?

You don't need a computer to make a nice oval. Two nails, a loop of
string and a pencil will do it.

Drive the nails in along the centre line of your oval evenly spaced
apart, then place a loop of string around the nails place the pencil in
the loop and draw the oval. The shape of the oval is determined by the
the distance apart the nails are (closer together more like a circle,
further apart opposite)the size of the oval is determined by the length
of the string.

Mekon

Bonehenge (B A R R Y) wrote:
With your tool selection, I might make this out of blue 2" thick foam
insulation board, skinned with 1/4" cabinet grade baltic birch ply and
1/8" ply or plastic laminate (countertop stuff) edges.

Thanks. I like the idea of the foam rather than ribs and stringers.
Can 1/8" ply (is that plywood or something else?) be curved that tightly
just by hand? Wouldn't it fight pretty hard to separate from the foam?
Or would you somehow join the ends together with something on the
inside? Why are you suggesting 1/8" ply rather than just a strip of
veneer? Any thoughts on how to nicely cut four-inch strips of plywood
with no table saw?

I presume you'd glue the plywood to the foam before cutting the ellipse.
How would I smooth out imperfections in the curve? Also seems like it
would be hard to keep the sides of the foam exactly vertical using a
hand-held jigsaw. Maybe that's why 1/8" plywood rather than veneer?

How would you attach it to the ceiling? 1/4" plywood seems too shallow
to take eyehooks. Would I cut four holes in the foam and glue thicker
blocks in there?

I was being imprecise when I said oval. I actually meant an ellipse, or
possibly a superegg.

On Sun, 13 Jan 2008 16:56:38 -0600, Mr Downtown "Mr Downtown" wrote:

Bonehenge (B A R R Y) wrote:
With your tool selection, I might make this out of blue 2" thick foam
insulation board, skinned with 1/4" cabinet grade baltic birch ply and
1/8" ply or plastic laminate (countertop stuff) edges.

Thanks. I like the idea of the foam rather than ribs and stringers.
Can 1/8" ply (is that plywood or something else?) be curved that tightly
just by hand?

Yup. You can also wet it or steam it to help.

Wouldn't it fight pretty hard to separate from the foam?
Or would you somehow join the ends together with something on the
inside? Why are you suggesting 1/8" ply rather than just a strip of
veneer?

Less "wiggles". The 1/8" ply will fight the bend enough to stay
smooth. I would think up a design feature that incorporates the
joint, rather than trying to completely hide it. Google Images
"Shaker Box".

Any thoughts on how to nicely cut four-inch strips of plywood
with no table saw?

A sharp craft knife (Xacto) knife and steel straight edge can cut 1/8"
ply easily. I did it for years on large scale model aircraft. You'll
make several passes with the knife.

I presume you'd glue the plywood to the foam before cutting the ellipse.
How would I smooth out imperfections in the curve? Also seems like it
would be hard to keep the sides of the foam exactly vertical using a
hand-held jigsaw.

Use a bread knife or coping saw, smoothed with a sanding block and 80-
grit paper. I'd use the perfected foam as a pattern for the 1/4" ply.
Cut the ply _slightly_ oversize, glue it,and sand to the foam.

Maybe that's why 1/8" plywood rather than veneer?

How would you attach it to the ceiling? 1/4" plywood seems too shallow
to take eyehooks. Would I cut four holes in the foam and glue thicker
blocks in there?

That would probably work well. Remember, this thing won't weigh a
lot.

I was being imprecise when I said oval. I actually meant an ellipse, or
possibly a superegg.

Foam is very easy to work and form. G

Somebody wrote:
Can 1/8" ply (is that plywood or something else?) be curved that tightly
just by hand?

Yes, especially if you use bending ply.

Lew