New here! wide-span shelf - Woodworking Talk - Woodworkers Forum
 
Thread Tools Display Modes
post #1 of 17 Old 08-16-2019, 04:02 PM Thread Starter
Junior Member
 
Join Date: Aug 2019
Location: NY
Posts: 7
View rvi17's Photo Album My Photos
New here! wide-span shelf

Hello everyone!
This if my first post and I wanted to ask for advice -

As a kind of first big project, I wanted to build a simple bookcase (that will actually be used for clothes, not books.)
I want to fit it snugly in a nook I have in my closet, that means the shelves will be wide - 55 inches.

My question is should I address sagging and add some support? or because it will hold shirts and sweaters, it's not that critical?

Thank you!

Raz
rvi17 is offline  
Sponsored Links
Advertisement
 
post #2 of 17 Old 08-16-2019, 04:09 PM
Wood machinist
 
difalkner's Avatar
 
Join Date: Nov 2011
Location: NW Louisiana
Posts: 3,374
View difalkner's Photo Album My Photos
Welcome to the forum, Raz! Add your location to your profile so it shows in the side panel. Add your first name to your signature line so it shows in each post.

Will these be 4/4 or 3/4 shelves? Which wood? Will the shelves have aprons? How many shirts and sweaters? Without knowing these things my first pass would be to add some sort of support. Also, if you have plans, sketches, photos of similar pieces, etc. then that may help in getting a good answer for you.

David

David

Curly Wood Shop on Etsy
David Falkner - Woodworking YouTube channel
Our music at church - current videos Airline Baptist BC Facebook Live
Romans 3:23
difalkner is online now  
post #3 of 17 Old 08-16-2019, 04:21 PM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,585
View woodnthings's Photo Album My Photos
So, you need a closet shelf for sweaters?

That's much different than a book shelf! So the rules for those don't apply here. I have used 3/4" plywood up to 48" wide for a similar application. I wouldn't use it for a 55" wide shelf however unless it was reinforced with a steel 1 1/2" X 1/8" thick angle. It may not sag, but it won't look good if it should. A better material would be 3/4" or 1" thick hardwood like Oak. Plywood would have to run lengthwise, and that's not very stiff compared to the Oak. The width of the shelf may be up to 24" as in my case, so gluing two pieces together will be necessary. this will add strength because you can oppose the grain directions.

A lot depends on the manner of supporting the shelf at the rear. A continuous support will be better than just at the ends. A 1 1/2" or 2" wide Oak strip glued to the front edge will add stiffness and that's what I'd do.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is online now  
Sponsored Links
Advertisement
 
post #4 of 17 Old 08-16-2019, 05:33 PM
Senior Member
 
Join Date: Jul 2008
Location: Florida Panhandle
Posts: 11,677
View GeorgeC's Photo Album My Photos
Any normal dimension shelf(3/4x12) that is 55" long will probably over time sag just of its weight.


George
GeorgeC is offline  
post #5 of 17 Old 08-16-2019, 05:50 PM
CharleyL
 
Join Date: Jan 2019
Location: Central North Carolina
Posts: 116
View CharleyL's Photo Album My Photos
An online program called "sagulator" might help. https://www.woodbin.com/calcs/sagulator/

I haven't used it myself, but friends have and have made good comments about it.

Charley
CharleyL is offline  
post #6 of 17 Old 08-16-2019, 06:02 PM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,585
View woodnthings's Photo Album My Photos
I entered the values I suggested ....

Quote:
Originally Posted by CharleyL View Post
An online program called "sagulator" might help. https://www.woodbin.com/calcs/sagulator/

I haven't used it myself, but friends have and have made good comments about it.

Charley

I entered 3/4" Red Oak with a 2" X 3/4" front strip, 55" long with a 30 lb load and it came back as .02" per foot... acceptable

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 08-16-2019 at 06:52 PM.
woodnthings is online now  
post #7 of 17 Old 08-16-2019, 06:22 PM Thread Starter
Junior Member
 
Join Date: Aug 2019
Location: NY
Posts: 7
View rvi17's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
That's much different than a book shelf! So the rules for those don't apply here. I have used 3/4" plywood up to 48" wide for a similar application. I wouldn't use it for a 55" wide shelf however unless it was reinforced with a steel 1 1/2" X 1/8" thick angle. It may not sag, but it won't look good if it should. A better material would be 3/4" or 1" thick hardwood like Oak. Plywood would have to run lengthwise, and that's not very stiff compared to the Oak. The width of the shelf may be up to 24" as in my case, so gluing two pieces together will be necessary. this will add strength because you can oppose the grain directions.

A lot depends on the manner of supporting the shelf at the rear. A continuous support will be better than just at the ends. A 1 1/2" or 2" wide Oak strip glued to the front edge will add stiffness and that's what I'd do.
Quote:
Originally Posted by GeorgeC View Post
Any normal dimension shelf(3/4x12) that is 55" long will probably over time sag just of its weight.


George
Quote:
Originally Posted by CharleyL View Post
An online program called "sagulator" might help. https://www.woodbin.com/calcs/sagulator/

I haven't used it myself, but friends have and have made good comments about it.

Charley
Quote:
Originally Posted by woodnthings View Post
I entered 3/4" Red Oak with a 2" X 3/4" front strip, 55" long with a 30 lb load and it came back as .02" per foot... acceptable

Thank you all for the quick replies!
I thought of using 3/4 plywood.
In case I do need to put support, I just thought of having a divider in the middle, making the shelves a little less than half the span.
I'm thinking of only using dadoes and rabbets (with glue, thin screws going through the end grain, and wood filler on top).
If I do decide on a divider in the middle - will it be ok to make it a 3/4, with a 1/4 rabbet on each side (for a shelf from each side). Or you probably have a better solution?

Thanks again!

Raz
rvi17 is offline  
post #8 of 17 Old 08-20-2019, 11:32 PM Thread Starter
Junior Member
 
Join Date: Aug 2019
Location: NY
Posts: 7
View rvi17's Photo Album My Photos
I'm attaching my design. Instead of a long span, I have 1/4'' dadoes in a 3/4'' plywood. Is that too much?
Thanks.
Attached Thumbnails
Click image for larger version

Name:	1566358254047567709480838661533_1566358279249.jpg
Views:	18
Size:	215.9 KB
ID:	378091  

Click image for larger version

Name:	15663582919461884114234839745315_1566358302982.jpg
Views:	18
Size:	227.5 KB
ID:	378093  

rvi17 is offline  
post #9 of 17 Old 08-21-2019, 04:42 AM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,585
View woodnthings's Photo Album My Photos
I have book shelve made like yours .....

I used 3/4" Oak with 1/4" dados on the sides and a center support with 1/4" dados on each side. If also fits between 2 walls, like yours. So, here what I did. I measured the distance between the two walls as accurately as possible using two sticks that overlap and taped them together when I butted them against the walls. I tested it at the floor and up from the floor to see if the walls were vertical. Then use a tape measure on the sticks to get an accurate width measurement.

Let's say your measurement was exactly 55".

Let's allow 1/8" gap for installation.
This results in a 54 7/8" over all width.
Now we need to allow for the two 1/4" dados at each side and the two center 1/4" dados.
Each shelf would need to be 27 7/16" ... minus 1/2" for dados or 26 15/16" wide.
Please check my math as it's 4:40 AM ......

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 08-21-2019 at 04:45 AM.
woodnthings is online now  
post #10 of 17 Old 08-21-2019, 09:42 AM
Senior Member
 
Join Date: Jul 2016
Posts: 609
View Terry Q's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
I used 3/4" Oak with 1/4" dados on the sides and a center support with 1/4" dados on each side. If also fits between 2 walls, like yours. So, here what I did. I measured the distance between the two walls as accurately as possible using two sticks that overlap and taped them together when I butted them against the walls. I tested it at the floor and up from the floor to see if the walls were vertical. Then use a tape measure on the sticks to get an accurate width measurement.

Let's say your measurement was exactly 55".

Let's allow 1/8" gap for installation.
This results in a 54 7/8" over all width.
Now we need to allow for the two 1/4" dados at each side and the two center 1/4" dados.
Each shelf would need to be 27 7/16" ... minus 1/2" for dados or 26 15/16" wide.
Please check my math as it's 4:40 AM ......


Except plywood isn’t 3/4 inch thick. Need to account for the 1/32nd difference in thickness times 3.


In woodworking there is always more then one way to accomplish something.
Terry Q is online now  
post #11 of 17 Old 08-21-2019, 04:10 PM
1948
 
Join Date: Jul 2018
Location: Dutchess County, NY
Posts: 492
View Packard's Photo Album My Photos
I saw on TV the other day (Hidden Potential, HGTV) where three 13' long book shelves were installed against a wall. It appeared to be 1" (full inch) thick reclaimed lumber, but the species was not identified in the show. They ran two short cletes at the shelf ends and one long cleat the length of the shelf against the wall. Then screwed the shelves to the cleats.

I'll admit I was concerned about the load in the middle of the shelf, but they loaded the shelf from end to end with books and it seemed fine on TV.

In any event I think I would be comfortable with 3/4" plywood with a 3/4" x 1˝" nosing glues and nailed and a cleat across the the wall for the shelf to rest on for a 55" span. The nosing might be optional. I would not use MDF or particle board for the shelving, but lumber would probably be fine to. Plywood is cheaper and I would probably go with the plywood.
Packard is online now  
post #12 of 17 Old 08-21-2019, 04:40 PM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,585
View woodnthings's Photo Album My Photos
Lumber is more stiff than plywood .....

https://www.google.com/search?client...wood+or+lumber


http://www.howstuffcompares.com/doc/...solid-wood.htm


I knew instinctively that plywood is not a stiff as the Oak I've used for all my book shelves. So, I searched, and it was indeed true. It may be cheaper, but sometimes the extra cost is worth it.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 08-21-2019 at 04:43 PM.
woodnthings is online now  
post #13 of 17 Old 08-22-2019, 08:34 AM
1948
 
Join Date: Jul 2018
Location: Dutchess County, NY
Posts: 492
View Packard's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
https://www.google.com/search?client...wood+or+lumber


http://www.howstuffcompares.com/doc/...solid-wood.htm


I knew instinctively that plywood is not a stiff as the Oak I've used for all my book shelves. So, I searched, and it was indeed true. It may be cheaper, but sometimes the extra cost is worth it.
Neither of the links worked for me so I could not read them.

Realistically, the plywood is fine. Sagulator lists a 55" wide x 12" deep shelf with no edging as having an acceptable load of 35 pounds per linear foot or about 161 total pounds.

Add an 3/4" x 1˝" front edging and it jumps to 60 pounds per linear foot or about 276 total pounds.

Add the rear cleat and it probably jumps to over 100 pounds per linear foot or about 461 total pounds.

So solid lumber would be stronger (but has other issues such as cost, potential to warp, seasonal expansion and shrinkage, etc.), but so would a steel shelf.

In my opinion the plywood, properly fastened at both ends and with a cleat against the wall would be stronger than required. A front edging would look nice and add to that strength.
Packard is online now  
post #14 of 17 Old 08-22-2019, 11:53 AM
Senior Member
 
Join Date: Aug 2017
Posts: 1,795
View Tool Agnostic's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
https://www.google.com/search?client...wood+or+lumber


http://www.howstuffcompares.com/doc/...solid-wood.htm


I knew instinctively that plywood is not a stiff as the Oak I've used for all my book shelves. So, I searched, and it was indeed true. It may be cheaper, but sometimes the extra cost is worth it.
There is another active thread going now, about French cleats. The OP there mentioned making them from MDF. I think that's a bad idea and recommended hardwood. I posted that I bought maple for my future French cleats. Coming soon, I hope.

https://www.woodworkingtalk.com/f17/...rength-214131/

I chose hardwood over plywood for the cleats, partially based on the same article that @woodnthings posted above. I will leave the question of shelf material to others in this discussion, but I wonder what material @rvi17 will use for the cleats?
Tool Agnostic is offline  
post #15 of 17 Old 08-22-2019, 12:24 PM
Senior Member
 
Join Date: Aug 2012
Location: British Columbia, Canada
Posts: 5,056
View FrankC's Photo Album My Photos
Quote:
Originally Posted by rvi17 View Post
I'm attaching my design. Instead of a long span, I have 1/4'' dadoes in a 3/4'' plywood. Is that too much?
Thanks.
This is how I would build it from what you show, bearing in mind that walls are not always exactly plumb in most houses so precutting calculations do not always work.

What you show is fine, 1/4" dados are adequate, make the uprights, install outside pair and the measure length required for the top. Install the top and centre support, now measure the length required for each shelf, which will be distance to bottom of dados on sides minus thickness of centre shelf.

Fasten shelves by toe nailing from underneath, screws also work, start with top shelf so there is room to drive them. All you need to do is stop shelves from sliding out, couple small finishing nails would be sufficient.

An alternative would be to add narrow face boards that would hold shelves in place.

“Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth.”
― Marcus Aurelius
FrankC
http://sawdustmaking.com
FrankC is online now  
post #16 of 17 Old 08-22-2019, 01:27 PM
1948
 
Join Date: Jul 2018
Location: Dutchess County, NY
Posts: 492
View Packard's Photo Album My Photos
Quote:
Originally Posted by Tool Agnostic View Post
There is another active thread going now, about French cleats. The OP there mentioned making them from MDF. I think that's a bad idea and recommended hardwood. I posted that I bought maple for my future French cleats. Coming soon, I hope.

https://www.woodworkingtalk.com/f17/...rength-214131/

I chose hardwood over plywood for the cleats, partially based on the same article that @woodnthings posted above. I will leave the question of shelf material to others in this discussion, but I wonder what material @rvi17 will use for the cleats?
I would not make french cleats from plywood (easily delaminated) or MDF or particleboard either. The MDF and Particleboard, unless painted are subject to deterioration due to moisture. Also neither of them are "structural". I would not use those materials for french cleats.

I did use 3/4" thick pressure treated for french cleats for flower boxes I made. I think one of the cleats is pulling away from the wall and needs additional fasteners. If it does not fall down before October I will take the box down and see what is wrong. I don't think it is the pine that is at issue. I think it is an inadequate number of anchors and screws. I only used three fasteners per 40" long box. With soil and water it probably got too heavy.

I've also used pine for French cleats for a sign holder (holds a roll of 30" wide brown paper) which is quite heavy. I have no issues with that French cleat.

Hardwood would be superior, but I generally use whatever is available in my scrap pile of wood. The cleats do not show.
Packard is online now  
post #17 of 17 Old 08-24-2019, 01:12 PM Thread Starter
Junior Member
 
Join Date: Aug 2019
Location: NY
Posts: 7
View rvi17's Photo Album My Photos
Thanks everyone for your input.
So this was my first project, it was kind of rushed, because the wife really needed a place to unpack our clothes to (we just moved to a new place).
I have decided to to use a middle partition so to not have a wide span shelf (from I read here, it would probably have been fine for clothes either way).
After buying the plywood and bringin it to the shop I saw that it was actually 23/32''. so I changed the measurements kind of on the fly. It's not exact, but I'm the only one who knows it :)
As for a first project, I'm satisfied. I definitely have a lot more to learn.

(for now, i'm not covering the plywood grain, I kinda like it)

Thanks again,

Raz
Attached Thumbnails
Click image for larger version

Name:	cabinet.jpg
Views:	16
Size:	360.6 KB
ID:	378161  

rvi17 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome