Hi all,
I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes in
the sides of the bookcase and others will be "floating", supported by pins
inserted in 1/2 inch deep holes. The shelves will only be supported on the
sides; not along the length. Should I worry about the sag of the plywood?
What's a good length of the shelf that can sustain a load full of books
without additional lengthwise support?
Thanks!
Vlad
On Thu, 09 Sep 2004 15:24:55 GMT, "Vlad" <[email protected]> wrote:
>Hi all,
>
>I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
>35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes in
>the sides of the bookcase and others will be "floating", supported by pins
>inserted in 1/2 inch deep holes. The shelves will only be supported on the
>sides; not along the length. Should I worry about the sag of the plywood?
>What's a good length of the shelf that can sustain a load full of books
>without additional lengthwise support?
>Thanks!
>Vlad
>
A 35" span will require 3/4" ply, plus a 1.5" lip on the front to
prevent sagging. Rabbet the lip and secure with carpenter's glue and
biscuits or finishing nails. If you want super-strong shelves, put a
lip on the back as well as the front. Half inch ply is just not
practical for heavy loads.
http://www.woodbin.com/calcs/sagulator.htm
"Vlad" <[email protected]> wrote in message
news:bB_%[email protected]...
: Hi all,
:
: I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
: 35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes in
: the sides of the bookcase and others will be "floating", supported by pins
: inserted in 1/2 inch deep holes. The shelves will only be supported on the
: sides; not along the length. Should I worry about the sag of the plywood?
: What's a good length of the shelf that can sustain a load full of books
: without additional lengthwise support?
: Thanks!
: Vlad
:
:
How about an inch wide strip of 3/4 ply supporting the shelves lengthwise
both at the front and at the back of the shelf?
Would this help?
Vlad
"Bob Gramza" <[email protected]> wrote in message
news:2x%%[email protected]...
> http://www.woodbin.com/calcs/sagulator.htm
>
>
> "Vlad" <[email protected]> wrote in message
> news:bB_%[email protected]...
> : Hi all,
> :
> : I am planning a couple of bookshelves to be made from a 1/2 inch
plywood,
> : 35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes
in
> : the sides of the bookcase and others will be "floating", supported by
pins
> : inserted in 1/2 inch deep holes. The shelves will only be supported on
the
> : sides; not along the length. Should I worry about the sag of the
plywood?
> : What's a good length of the shelf that can sustain a load full of books
> : without additional lengthwise support?
> : Thanks!
> : Vlad
> :
> :
>
>
I would strongly second RonB's comments. A 36" wide shelf that's only 1/2"
thick is bound to sag, especially if not supported along the length. Upgrade
to 3/4" plywood at the very least. Wouldn't be surprised to see even the
3/4" sag if you don't use the oak/hardwood trim piece at the front edge of
the shelf.
If you have access to it, Andy Rae's "The Complete Illustrated Guide to
Furniture & Cabinet Construction" has lots of useful info relevant to what
you're asking about.
"Vlad" <[email protected]> wrote in message
news:bB_%[email protected]...
> Hi all,
>
> I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
> 35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes
in
> the sides of the bookcase and others will be "floating", supported by pins
> inserted in 1/2 inch deep holes. The shelves will only be supported on the
> sides; not along the length. Should I worry about the sag of the plywood?
> What's a good length of the shelf that can sustain a load full of books
> without additional lengthwise support?
> Thanks!
> Vlad
>
>
In article <bB_%[email protected]>,
Vlad <[email protected]> wrote:
>Hi all,
>
>I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
>35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes in
>the sides of the bookcase and others will be "floating", supported by pins
>inserted in 1/2 inch deep holes. The shelves will only be supported on the
>sides; not along the length. Should I worry about the sag of the plywood?
>What's a good length of the shelf that can sustain a load full of books
>without additional lengthwise support?
>Thanks!
>Vlad
>
>
1/2" plywood will sag to much for a 35" wide shelf full of books.
Unless you use 3/4" ply or add some kind of bracing or stiffener, you
probably should keep the length around 12" or so for 1/2" plywood.
--
Larry Wasserman Baltimore, Maryland
[email protected]
On Thu, 09 Sep 2004 16:15:38 GMT, "Rich B" <[email protected]> wrote:
>I would strongly second RonB's comments. A 36" wide shelf that's only 1/2"
>thick is bound to sag, especially if not supported along the length. Upgrade
>to 3/4" plywood at the very least. Wouldn't be surprised to see even the
>3/4" sag if you don't use the oak/hardwood trim piece at the front edge of
>the shelf.
>
My son has a creative punker friend who is only 17, he made a set of
(adjustable) shelves from 3/4 rough slabs and barb wire and nothing else. They
are suspended from a ceiling beam. Ouch!
They actually look pretty good.
>If you have access to it, Andy Rae's "The Complete Illustrated Guide to
>Furniture & Cabinet Construction" has lots of useful info relevant to what
>you're asking about.
>
>"Vlad" <[email protected]> wrote in message
>news:bB_%[email protected]...
>> Hi all,
>>
>> I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
>> 35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes
>in
>> the sides of the bookcase and others will be "floating", supported by pins
>> inserted in 1/2 inch deep holes. The shelves will only be supported on the
>> sides; not along the length. Should I worry about the sag of the plywood?
>> What's a good length of the shelf that can sustain a load full of books
>> without additional lengthwise support?
>> Thanks!
>> Vlad
>>
>>
>
On Thu, 09 Sep 2004 17:04:38 GMT, "Vlad" <[email protected]> wrote:
>How about an inch wide strip of 3/4 ply supporting the shelves lengthwise
>both at the front and at the back of the shelf?
>Would this help?
Why not a nice dadoed vertical strip up the middle front?
Looks nice, less work.
>Vlad
>
>
>
>"Bob Gramza" <[email protected]> wrote in message
>news:2x%%[email protected]...
>> http://www.woodbin.com/calcs/sagulator.htm
>>
>>
>> "Vlad" <[email protected]> wrote in message
>> news:bB_%[email protected]...
>> : Hi all,
>> :
>> : I am planning a couple of bookshelves to be made from a 1/2 inch
>plywood,
>> : 35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes
>in
>> : the sides of the bookcase and others will be "floating", supported by
>pins
>> : inserted in 1/2 inch deep holes. The shelves will only be supported on
>the
>> : sides; not along the length. Should I worry about the sag of the
>plywood?
>> : What's a good length of the shelf that can sustain a load full of books
>> : without additional lengthwise support?
>> : Thanks!
>> : Vlad
>> :
>> :
>>
>>
>
"Vlad" <[email protected]> wrote in message
news:bB_%[email protected]...
>
>
> Hi all,
>
> sides; not along the length. Should I worry about the sag of the plywood?
yes. 35" span with books and half-inch ply will most likely sag
> What's a good length of the shelf that can sustain a load full of books
> without additional lengthwise support?
Depends on the books. How many copies of Lehninger's Principles of
Biochemistry are on them?
I rarely go over 32" with 3/4" plywood. Dunno for 1/2".
(Even 32" and 3/4" will sag some, about 1/32nd to 1/16")
On Thu, 09 Sep 2004 15:24:55 GMT, "Vlad" <[email protected]> wrote:
>Hi all,
>
>I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
>35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes in
>the sides of the bookcase and others will be "floating", supported by pins
>inserted in 1/2 inch deep holes. The shelves will only be supported on the
>sides; not along the length. Should I worry about the sag of the plywood?
>What's a good length of the shelf that can sustain a load full of books
>without additional lengthwise support?
>Thanks!
>Vlad
>
Your shelf will sag about 0.30 inch over a 35" length. Anything over
.09" would be noticeable, according to the Sagulator:
http://www.woodbin.com/calcs/sagulator.htm
You'll do well to follow the many suggestions to upgrade the shelf
thickness and add stiffener(s).
http://mywebpages.comcast.net/wgoffeney/Woodworking/Woodworking.htm
Yes - you might sag, especially with books. Consider doing both of the
following:
Upsize your shelf to 3/4 plywood - quite a bit stiffer
Trim the front with a piece of oak about 3/4" wide by 1" or 1-1/4" high.
You can route or roll the edges for appearance. It will give you a little
more edge stiffness.
"Vlad" <[email protected]> wrote in message
news:bB_%[email protected]...
> Hi all,
>
> I am planning a couple of bookshelves to be made from a 1/2 inch plywood,
> 35x11 inches in size; some shelves will be fixed in 1/4 inch deep dadoes
in
> the sides of the bookcase and others will be "floating", supported by pins
> inserted in 1/2 inch deep holes. The shelves will only be supported on the
> sides; not along the length. Should I worry about the sag of the plywood?
> What's a good length of the shelf that can sustain a load full of books
> without additional lengthwise support?
> Thanks!
> Vlad
>
>