I'm building a desktop that will have about an 8" overhang on the front
as well as an unsupported span of about 30" in the kneehole area. The
material for the desktop is 3/4" quartersawn white oak plywood. I
considered a torsion box (per Niall Barrett's Desk book) but am afraid
that the desktop will become too thick. I'm considering laminating
the 3/4" plywood to some 3/4" particleboard then banding the edges with
some 5/4 stock bicuited into the sides. But something makes me think
this is a bad idea. I fear the plywood and particleboard, while both
pretty stable, may nonetheless react a bit differently and cause me
some problems down the line.

I've scoured the net and this board but haven't found anything quite on
point. Has anyone tried this successfully? Would laminating the
bottom with 1/4" plywood be good insurance against warpage? I'd really
like to keep the thickness around 1 1/2" if possible.

Thanks,

Steve Polaski

On Mon, 30 Jan 2006 15:51:58 -0800, polaski.steve wrote:

I'm building a desktop that will have about an 8" overhang on the front
as well as an unsupported span of about 30" in the kneehole area. The
material for the desktop is 3/4" quartersawn white oak plywood. I
considered a torsion box (per Niall Barrett's Desk book) but am afraid
that the desktop will become too thick. I'm considering laminating
the 3/4" plywood to some 3/4" particleboard then banding the edges with
some 5/4 stock bicuited into the sides. But something makes me think
this is a bad idea. I fear the plywood and particleboard, while both
pretty stable, may nonetheless react a bit differently and cause me
some problems down the line.

I've scoured the net and this board but haven't found anything quite on
point. Has anyone tried this successfully? Would laminating the
bottom with 1/4" plywood be good insurance against warpage? I'd really
like to keep the thickness around 1 1/2" if possible.

Thanks,

Steve Polaski

Steve,

I've successfully made torsion box tabletops of about 1 1/4" thick using
1/4 inch material. I also made a platform bed using 1/2" plywood with 1
1/2" webbing (pretty beefy). You could use 1/2" material for the tops and
bottoms with 3/4" material for the web. I've successfully used foam
insulation as the core material. Just an idea.

DGA

wrote:
I'm building a desktop that will have about an 8" overhang on the front
as well as an unsupported span of about 30" in the kneehole area. The
material for the desktop is 3/4" quartersawn white oak plywood. I
considered a torsion box (per Niall Barrett's Desk book) but am afraid
that the desktop will become too thick. I'm considering laminating
the 3/4" plywood to some 3/4" particleboard then banding the edges with
some 5/4 stock bicuited into the sides. But something makes me think
this is a bad idea. I fear the plywood and particleboard, while both
pretty stable, may nonetheless react a bit differently and cause me
some problems down the line.

I've scoured the net and this board but haven't found anything quite on
point. Has anyone tried this successfully? Would laminating the
bottom with 1/4" plywood be good insurance against warpage? I'd really
like to keep the thickness around 1 1/2" if possible.

Thanks,

Steve Polaski

All you need is the 3/4" plywood for the top. Put
3/4" x 1-1/2 squirt, band, edge or whatever you
call it all the way around. And you don't need
the biscuits. Don't know what your fear of the
banding is unless you make a 10 foot desk. There
should be no warpage if you make sure you add
finish to all surfaces. I made a desk with a
similar top about 30"x48" in 1974. No problems yet.

wrote in message
ups.com...
I'm building a desktop that will have about an 8" overhang on the front
as well as an unsupported span of about 30" in the kneehole area. The
material for the desktop is 3/4" quartersawn white oak plywood. I
considered a torsion box (per Niall Barrett's Desk book) but am afraid
that the desktop will become too thick. I'm considering laminating
the 3/4" plywood to some 3/4" particleboard then banding the edges with
some 5/4 stock bicuited into the sides. But something makes me think
this is a bad idea. I fear the plywood and particleboard, while both
pretty stable, may nonetheless react a bit differently and cause me
some problems down the line.


Real problem will be keeping your pen from digging in to a plywood top. Use
a blotter.

If you want reinforcement, make it part of your design. Rabbet and drop an
inch and a half of solid 3/4 stock all around, with perhaps a couple of
fully glued lengths of three quarter longitudinally where you won't see
them.

Other, and better technique to my thinking is to laminate a 1" piece to a 1
3/4" piece of 3/4 oak stock (other piece need not be oak) to use as edging
so you can have a good 5/8 or even 3/4 radius roundover to keep from marking
your forearms.

wrote in message

the 3/4" plywood to some 3/4" particleboard then banding the edges with
some 5/4 stock bicuited into the sides.

You will do fine leaving out the particle board.

--
www.e-woodshop.net
Last update: 12/13/05

Thank you all so much for your replies. I think I'll take Swingman's
and George Cawthon's advice and skip the particleboard substrate.
Since the desk is in my own house, I can always go back later and
stiffen if should it not work out.

And per George's "Real problem will be keeping your pen from digging in
to a plywood top. Use
a blotter. "

Absolutely.

Thanks again everyone - your input is very much appreciated.

Exactly. Make it more like a funky H-beam than a slab. Ditto that on
pen digging in, unless OP goes for some close-grained
hardwood-laminated ply.

J

Just to close the loop on this. I built the top with 1 1/2" thick 5/4
stock around the edges of the plywood. The desktop came out plenty
stiff. My concern was the overhang but I can barely get it to flex
even putting my 230 pound frame on it. I put 5 coats of poly on the
top so it should hold up as long as my kids don't attack it.

Thanks again everyone,

Steve