# Sturdiest way to put a back on a bookcase?



## jtolbert (May 16, 2018)

My wife is a special-ed teacher at a local grade school. Special-ed teachers basically never get anything new; everything in her room is hand-me-downs from other classrooms. She has some short bookcases in her room that have seen better days, so she's been looking to replace them, but with a few extra criteria in the design to meet her needs better. They'll be basic two-shelf bookcases made from 3/4" Baltic birch ply for the majority and 1/2" ply for the backs, around 33-34" long, fairly short at 26-1/4" tall, and 12" deep with back included so they can hold three-ring binders nicely. These will get painted a pretty neutral color so they blend in with the rest of the stuff in her room, so "fancy" isn't a requirement here...But "sturdy" is. Anyone that knows much about teachers knows they overload their shelves. The dimensions are fine and all, and I have no issues with building them that I can see...Except for the back.

What's the sturdiest way to build a bookcase with a back? I've seen people just build the top/sides/bottom/shelves and screw an appropriately-sized piece on the back, but that always looked bad to me. I've seen others rabbet in a back while cutting the shelves short by the width of the back and screwing the shelves into the back from behind. I've seen people rabbet in a back on the sides while just butting the back on the inside surfaces of the top/bottom. I've seen people rout a dado for the shelves and glue them in. How do the pros do it, or what would you recommend?

As it stands right now I'm probably going to just glue/pocket-hole the top/bottom/sides together, so nothing fancy there. I'm leaning towards just rabbeting the sides, flushing the back in with the inside surfaces of the top/bottom, pocket-holing the back to the top/bottom and just pocket-holing the shelf to the back. Straight cuts for the sides to mate to the top/bottom will be quick and easy, rabbeting the sides will be easy, I can dado both sides for the shelf in one shot easily, assembly should be pretty simple for one guy working on his own, and it should be pretty sturdy. Am I on the right track here? I'll eventually be banging out four of these for my wife's classroom.

Thanks!


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## Steve Neul (Sep 2, 2011)

I've never put a 1/2" back on a bookcase. I've always used 1/4" plywood which I apply with glue and staples. You would tear the back all to pieces trying to get it off. 

You might get some more use out of the old cabinets if you wish. If there has been a back glued on it before the glue won't hold the second time. I would just attach it with flat head screws. Just make sure the screws are long enough. 1 1/4" drywall screws should work for a 1/2" thick back. If you could predrill the holes and countersink them it would help.


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## Toolman50 (Mar 22, 2015)

If you’re building new bookcases you can plan your project by narrowing the shelves 1/4” to accommodate a 1/4” back that is recessed into the sides with a 1/4” rabbet. This makes for a very strong case with the back hidden from a side view. (Best way)

If your re-working existing bookshelves, you may have to attach the back directly to the edges of the sides. The edge of the back will be visible from the side but it will still be strong.

The back can be stapled, nailed or screwed about every 6” to the sides and shelving. Glue or no glue.


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## jtolbert (May 16, 2018)

Yeah, I suppose 1/2" backs are a bit overkill. That's what the bookcases we're replacing had, so that's what I was planning on using.


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## woodnthings (Jan 24, 2009)

*confused over here ...?*



Toolman50 said:


> If you’re building new bookcases you can plan your project by narrowing the shelves 1/4” to accommodate a 1/4” back that is recessed into the sides with a 1/4” rabbet. This makes for a very strong case with the back hidden from a side view. *(Best way)*
> 
> If your re-working existing bookshelves, you may have to attach the back directly to the edges of the sides. The edge of the back will be visible from the side but it will still be strong.
> 
> The back can be stapled, nailed or screwed about every 6” to the sides and shelving. Glue or no glue.





jtolbert said:


> Yeah, I suppose 1/2" backs are a bit overkill. That's what the bookcases we're replacing had, so that's what I was planning on using.


Are you repairing existing ones or building one ones?
For replacement backs or new ones, all you need is 1/4" plywood.
Obviously a new back added to the existing one will show around the perimeter what ever the new plywood thickness is.

Building new ones requires the shelves be set back from the rabbet as toolman suggests. Trying to line up dados and shelves into the back can be a glue up nightmare. A butt joint with glue and nails is fine. Make your nail lines while dry fitting the back before using any glue. Use only a thin line of glue on the shelf edges to avoid a squeeze out mess on the inside.

I almost always dado my shelves into the sides but not the back. 
Here's one instance where I did not to that:
http://www.woodworkingtalk.com/f13/building-shelves-my-methods-123314/

By cutting plywood scraps to the width of the shelf spacing, I was able to insert them as spacers between the shelves during the glue up. They were removed after gluing and nailing in from the sides, since they were just temporary.
 

Sometimes you screw up.:vs_cool:

I had to use the "board extender" to make a shelf a bit longer. I made matching dados on the ends of both pieces so the surface were flush and then glued them together:


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## andr0id (Jan 11, 2018)

I just build a cabinet very similar (but smaller) in construction to woodnthings photos.

I did a rabbet around the side edges and top bottom edges, set the shelving in 1/4" and glued and pin nailed in 1/4" plywood. I stretched a string across where all the shelves were to make sure I got the pin nails into the back of the shelves and not into air. It worked very well, I only ended up missing twice out of a hundred or so nails.

That's plenty strong for normal use. 



However if you you think her students might abuse the shelves or climb on them, using 1/2" would certainly make them indestructible.


And maybe put on one extra pocket hole screw per joint. I used 3 per side joint (18"), but you might go to 4, kreg screws aren't that pricey. I'd just be mildly worried about some kid managing to get hurt on it.


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## mmwood_1 (Oct 24, 2007)

jtolbert, I have built cabinets, bookshelves, cubbies, etc for 3 different schools. If the bookshelf will have its back against the wall, 1/4" will be fine, rabbetted into the top, bottom, and sides. I rabbett in 3/8". If the bookshelf will be in the open, then I would go 3/8"-1/2" for the back, because it would be subjected to possibly being inadvertently kicked. The standard 1/4" ply today is 3/16" thick and not terribly strong. On the other hand, if you use baltic birch, it is thicker and stouter. Either way, rabbet the perimeter for the back, glue, and put finish nails in through the back into the center shelf about every 8" will be plenty strong.


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## jtolbert (May 16, 2018)

Very cool. Seems like rabbeting completely around the back is the way to go. Thank you all!

I'm pretty certain these are going along walls, so 1/4" should be fine. Thanks again!


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## NoThankyou (Mar 21, 2018)

Yes, rabbet around the back. Also set the shelves in from the back the depth of the rabbet. 

Assemble everything, except for the back. Fit the back, snug. (I'm assuming that you are using Baltic Birch plywood.) Use a light application of glue in the rabbets and shelves. (I'm assuming TiteBond something or other.) Then as Norm would say, "Shoot nails or staples to hold the back in place until the glue dries." Use a spackle or joint compound on the exposed edges of the Baltic Birch. It will give a really nice finish when painted.


Your nail gun should be a 18 gauge. If you don't have a compressor and nail gun, now is an excellent time to get one.


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## ducbsa (Jul 6, 2014)

Don't forget to measure diagonally and verify that the case is square before you fasten down the back.


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## jtolbert (May 16, 2018)

Thanks again. Useful stuff. Yeah, I'm familiar with squaring up stuff. I have a compressor and I can borrow a nail gun...I should probably pick up my own at some point.


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## Steve Neul (Sep 2, 2011)

I've always used the plywood back to square a cabinet.

If you are going to buy a nail gun, harbor freight guns work well and are cheap.


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## Toolman50 (Mar 22, 2015)

jtolbert said:


> Thanks again. Useful stuff. Yeah, I'm familiar with squaring up stuff. I have a compressor and I can borrow a nail gun...I should probably pick up my own at some point.


For applying backs and other cabinet type work the term nail gun can be misleading for the application. For cabinet backs and general drawer assembly, a narrow crown finish stapler capable of driving staples with a crown of 3/16 or 1/4” in width and up to 1 1/2” in length will have more holding power than a nail.


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## jtolbert (May 16, 2018)

Toolman50 said:


> For applying backs and other cabinet type work the term nail gun can be misleading for the application. For cabinet backs and general drawer assembly, a narrow crown finish stapler capable of driving staples with a crown of 3/16 or 1/4” in width and up to 1 1/2” in length will have more holding power than a nail.


That's good to know. I used staples when I replaced pickets in my fence that got taken out by a falling tree. Thanks.


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## Toolman50 (Mar 22, 2015)

jtolbert said:


> That's good to know. I used staples when I replaced pickets in my fence that got taken out by a falling tree. Thanks.


We are straying from the original topic of cabinet backs but there are all types of nail guns and staple guns. Choosing the right one for the the application can make a big difference. 
For home construction, interior finish work, roofing, upholstery, etc, etc. 
For fencing, the best fastener is an aluminum ring shanked coil nail. This will outhold a staple or a slick nail and it doesn’t rust. All galvanized steel nails will rust over time. Some rust very quickly. A heavy duty staple can be used for fencing. It’s the same staple used to apply roof decking to the rafters, but the staple doesn’t hold as well as a nail.


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## gj13us (Apr 19, 2016)

ducbsa said:


> Don't forget to measure diagonally and verify that the case is square before you fasten down the back.



Or, in my case, I use the squared back to forcibly square up the case if it's out of square.


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## jtolbert (May 16, 2018)

So, I'm up to two bookcases mostly finished now. The first one is in use. I rabbeted in the back and used narrow-crown staples to keep it in place while the glue dried on both.

The white one is the first one. I have yet to figure out the secret for keeping pocket-holed/glued wood from moving around when you run the pocket-hole screws in. I bought some nice box clamps from Woodpeckers, but they didn't have enough pressure to keep the boards from moving when screwing the white one together, so it looks like garbage. Oh well, it lives in a closet and does its job.

My wife loved it. "Now, can you build two more? A three-shelf jobber 30" wide for here, and a four-shelf jobber, 34" wide, for here? Oh, and can I have them before school starts?" I'll probably get the three-shelf one done in time. 

I finished the major woodworking on the three-shelf one tonight. I kept things mostly from moving around by using the corner clamps again, but then also throwing an F clamp across the ends to hold the boards tight while running the pocket screws in. Worked much better.

My dadoes for the shelves were too tight on both; I had to resort to hammering the shelves in. Oh well; since they are glued and driven in I know they aren't going to go anywhere.

I'm pretty happy with the second one overall. None of the staples ended up sticking out anywhere. Almost all of the squeeze-out got cleaned up before it cured. Everything lines up pretty much where it needs to go. I still haven't figured out the trick for cutting the back out perfectly yet, mostly cause the 1/4" rabbet isn't enough to let me get a pencil in there to trace around the inside so I can cut it out.

I still have to trim the pocket-hole plugs off, round over some edges, sand, and polyurethane the second bookcase. I can't bring myself to paint it; I do not like painted wood. 

I ended up ruining the side boards on the four-shelf one; I have to buy another 5x5 of Baltic birch to make new ones. The bottom part of my shelf dado jig wasn't clamped down tight enough and it slid, making the dado tapered.

I ended up buying the Harbor Freight dual-purpose nailer/stapler, and it's worked out really well. Thank you all for your advice and guidance.


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## jtolbert (May 16, 2018)

https://photos.app.goo.gl/YpBQrirnAqewsA7aA <-- See, this is my problem. I had a braindrizzle tonight after midnight, which made me go check my stash of Dremel Multi-Max oscillating-tool bits...Turns out I had a flush-cutting wood blade for it...I knew my dad was still up, so I ran back over there and tried it out. Worked stupid well. Solved the pocket-hole plug trimming problem with what I had on hand instead of having to buy more tools, which I'm certain will make my wife happy.

I also tried the sanding attachment for the Multi-Max, which made short work of cleaning up the surface left by the flush-trim bit.

I bought the Multi-Max for de-grouting tile years ago, and have hardly used it at all since. I'll have to keep it handy when working on stuff.


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## Steve Neul (Sep 2, 2011)

I think you would be much happier if you would shelve the pocket hole jig and quit using it. Their marketing strategy has people using a pocket hole jig in ways it was never intended or should be used. The important thing to them is they sell jigs. Never mind what it does to the craft of woodworking. The pocket hole jig is suppose to be used in applications that don't show such as the back side of cabinet faceframes. You are plugging the holes and sanding it flat but the plugs won't stay there. In a few months the wood will shift and you will be able to see an outline of the plug. Even if you fill it again and repaint it again when the weather changes the plug will show again. The cabinet you built if you had inserted the top and bottom in a dado like the middle shelves it would have been fine and the plywood ends wouldn't show from the side. 

In the future when you assemble a cabinet I would recommend washing the glue off with a wet rag. Had you planned on staining the cabinet the glue spots wouldn't accept a stain. Even painting it sometimes the paint resists adhering to glue. 

From where you are I would recommend caulking the inside of the cabinet where the shelve and sides meet the back. This would make a lot cleaner look when painted.


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## jtolbert (May 16, 2018)

I'll have to give rabbeting in the top and bottom a try. Thanks.


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## Brian T. (Dec 19, 2012)

Right from the start, I'd inset the shell and the shelves so I could use a sheet of 1/8" mahogany "door skin".

My book cases down stairs are 48" wide by 90" tall and possibly 700-1,000 titles in each. 
The door skin on the back of each one is more than enough to maintain the dimensional stability.
Never knew how much fun a brad nailer would be.


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