I am building a sofa table out of 3/4" walnut using mortise and tenon
construction
for the back and side aprons.
The stretchers connecting the legs on the left and right sides (front
to back) lower
will also use mortise and tenon joinery.

I plan on using a piece of 3/4" walnut approximately 10" wide by 45"
long
to act as both a lower shelf and to act as a center stretcher
connecting
the two lower leg stretchers.
There will be a cleat on the interior of both the left and right lower
leg stretchers
which will support the shelf.

I am not planning on placing anything heavy on the shelf but I am
concerned about possible sag.

I thought about gluing lips on the front and back of the shelf which
would span the
entire length. I know that this is effective on bookshelves but I
rejected
this idea since I want the shelf thickness to equal the table top
thickness (3/4")

Since the bottom of the lower shelf will be about 7" above the floor
and not readily visible I thought about
glueing two 3/4" runners to the shelf the same length as the lower
shelf on either side of the cleats
supporting the shelf.
Or
milling two shallow dadoes about 1/4 deep by 3/8 wide and inserting
splines which would
sit about 1/2" proud of the bottom surface

Any one have any comments on this approach?
Any one see any problems?

All the best

In article om, toolista wrote:
I am building a sofa table out of 3/4" walnut using mortise and tenon
construction
for the back and side aprons.
The stretchers connecting the legs on the left and right sides (front
to back) lower
will also use mortise and tenon joinery.

I plan on using a piece of 3/4" walnut approximately 10" wide by 45"
long
to act as both a lower shelf and to act as a center stretcher
connecting
the two lower leg stretchers.
There will be a cleat on the interior of both the left and right lower
leg stretchers
which will support the shelf.

I am not planning on placing anything heavy on the shelf but I am
concerned about possible sag.

I thought about gluing lips on the front and back of the shelf which
would span the
entire length. I know that this is effective on bookshelves but I
rejected
this idea since I want the shelf thickness to equal the table top
thickness (3/4")

Since the bottom of the lower shelf will be about 7" above the floor
and not readily visible I thought about
glueing two 3/4" runners to the shelf the same length as the lower
shelf on either side of the cleats
supporting the shelf.
Or
milling two shallow dadoes about 1/4 deep by 3/8 wide and inserting
splines which would
sit about 1/2" proud of the bottom surface

Any one have any comments on this approach?
Any one see any problems?

A 45 inch unsupported span certainly has the potential
for sag under any significant load. I think you're
right to add some reinforcement.

I have some commerial bookcases with 36 inch span. Each
shelf has dado about 1/2in deep and 1/8in wide. A steel
spline is stapled therein and flush with the underside
of the shelf. 36 inch span, a ton of large/heavy reference
books, and no signs of sagging after 3 years.

I like the design. When I next make something like this
I'm planning to cut two dados and epoxy the steel splines
in them.

However, since the underside of your shelf will not be
visible, why not simply attach one or two strips of
steel T-section to it? You could use epoxy or lots of
screws.

--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
| Gary Player. |
| http://www.malch.com/ Shpx gur PQN. |
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~

"toolista" wrote in message
ps.com...
I am building a sofa table out of 3/4" walnut using mortise and tenon
construction
for the back and side aprons.
The stretchers connecting the legs on the left and right sides (front
to back) lower
will also use mortise and tenon joinery.

I plan on using a piece of 3/4" walnut approximately 10" wide by 45"
long
to act as both a lower shelf and to act as a center stretcher
connecting
the two lower leg stretchers.
There will be a cleat on the interior of both the left and right lower
leg stretchers
which will support the shelf.

I am not planning on placing anything heavy on the shelf but I am
concerned about possible sag.

I thought about gluing lips on the front and back of the shelf which
would span the
entire length. I know that this is effective on bookshelves but I
rejected
this idea since I want the shelf thickness to equal the table top
thickness (3/4")

Since the bottom of the lower shelf will be about 7" above the floor
and not readily visible I thought about
glueing two 3/4" runners to the shelf the same length as the lower
shelf on either side of the cleats
supporting the shelf.
Or
milling two shallow dadoes about 1/4 deep by 3/8 wide and inserting
splines which would
sit about 1/2" proud of the bottom surface

Any one have any comments on this approach?
Any one see any problems?

All the best

Hope this is of use to you:

http://www.woodbin.com/calcs/sagulator.htm

Tom

toolista wrote:

I am building a sofa table out of 3/4" walnut using mortise and tenon
construction
for the back and side aprons.
The stretchers connecting the legs on the left and right sides (front
to back) lower
will also use mortise and tenon joinery.

I plan on using a piece of 3/4" walnut approximately 10" wide by 45"
long
to act as both a lower shelf and to act as a center stretcher
connecting
the two lower leg stretchers.
There will be a cleat on the interior of both the left and right lower
leg stretchers
which will support the shelf.

I am not planning on placing anything heavy on the shelf but I am
concerned about possible sag.

I thought about gluing lips on the front and back of the shelf which
would span the
entire length. I know that this is effective on bookshelves but I
rejected
this idea since I want the shelf thickness to equal the table top
thickness (3/4")

Since the bottom of the lower shelf will be about 7" above the floor
and not readily visible I thought about
glueing two 3/4" runners to the shelf the same length as the lower
shelf on either side of the cleats
supporting the shelf.
Or
milling two shallow dadoes about 1/4 deep by 3/8 wide and inserting
splines which would
sit about 1/2" proud of the bottom surface

Any one have any comments on this approach?
Any one see any problems?

All the best

I glued a single runner along the bottom of 4' x 11" x 3/4" bookshelf, along
with a front lip, both 3/4" wide by about 2" wide. This not only provides
support for the shelf, it also provides (via braces) support for the shelf
above it, which supports the shelf above it, which supports the top. It's
been there a couple of years and no sag yet.

I imagine a single runner would do in your case.
--
Michael White "To protect people from the effects of folly is to
fill the world with fools." -Herbert Spencer

On Nov 6, 6:57 pm, toolista wrote:
I am building a sofa table out of 3/4" walnut using mortise and tenon
construction
for the back and side aprons.
The stretchers connecting the legs on the left and right sides (front
to back) lower
will also use mortise and tenon joinery.

I plan on using a piece of 3/4" walnut approximately 10" wide by 45"
long
to act as both a lower shelf and to act as a center stretcher
connecting
the two lower leg stretchers.
There will be a cleat on the interior of both the left and right lower
leg stretchers
which will support the shelf.

I am not planning on placing anything heavy on the shelf but I am
concerned about possible sag.

I thought about gluing lips on the front and back of the shelf which
would span the
entire length. I know that this is effective on bookshelves but I
rejected
this idea since I want the shelf thickness to equal the table top
thickness (3/4")

Since the bottom of the lower shelf will be about 7" above the floor
and not readily visible I thought about
glueing two 3/4" runners to the shelf the same length as the lower
shelf on either side of the cleats
supporting the shelf.
Or
milling two shallow dadoes about 1/4 deep by 3/8 wide and inserting
splines which would
sit about 1/2" proud of the bottom surface

Any one have any comments on this approach?
Any one see any problems?

All the best

Inset cleats will bear weight just as well as cleats set flush
with the edges.

Any thoughts of building a box beam under the shelf? You
could set your brick collection on the shelf without it sagging.