sawtooth or dado for bookcase? - Woodworking Talk - Woodworkers Forum
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post #1 of 14 Old 01-07-2019, 01:34 PM Thread Starter
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sawtooth or dado for bookcase?

I can't decide which one is stronger. Technically, I can run a few support bars under each of the shelves when I build each of them with a sawtooth system. On the other hand, I can also just dado a shelf into each side, back, and fixed front bar. That is going to be really strong.

But which one is stronger? I don't NEED adjustable bookcase shelves but they do not look that difficult to build as opposed to figuring out how to handle the dado joints across both sides and back.

I also really like that I can use 1.25inch wide teeth from my 6/4 stock rather than a 3/4in dado joint. What would you recommend?
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post #2 of 14 Old 01-07-2019, 02:06 PM
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What are the dimensions of the bookcase?

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post #3 of 14 Old 01-07-2019, 02:20 PM
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Never heard of a "sawtooth" shelf ......

I have made plenty of dados for shelves, however.



There is a far better way than either which will also give you shelves that are somewhat adjustable. You may need a dado for a center shelf for structure, however. Use rabbets on the top and bottom of the case and a dado for the center shelf. Once that's all assembled, cut your shelves to fit between the sides with a slip fit. Now, make "risers" for each end of any shelves at what ever height you want, all the same some longer than other ... etc. The risers can be 3/8" thick of the same wood as the rest of the cabinet. They will add 3/4" of thickness to the center strut if there is one, and 3/8" to the sides. All the shelves and their weight will rest on these 3/8" riser supports, just like they were in a 3/8" deep dado. Tack them or double stick tape them in place.


To make an accurate dado on both sides and across the back, tape the sides together back edge to back edge, so one pass across will be all you need. Use a "T" square router guide or measure precisely! Duplicate that on the back the same distance from the top or bottom. Line them all up and the dado should run smoothly across all 3 pieces.


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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)

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post #4 of 14 Old 01-07-2019, 05:43 PM Thread Starter
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The bookcase is going to be 6ft tall, 30in shelves interior, and probably 14in deep. At 6ft, the idea of adjustable shelving appealed to me.

I am trying to make the sides about 1.25in wide using rough sawn 6/4 white oak. I figured I would lose about .25in from it, more or less. I wouldn't want to go more than halfway through on a dado. I am going to dado into the sides a 3/4inch plywood sheet for the back and use 3/4inch plywood for the shelves. The bottom and top will be white oak, probably rabbited and dadoed in. The bottom shelf will sit 2in from the ground and have a 2in support, front panel, and maybe a bit of decoration or something.

Bookcases are a pain to design. Every single one I have had I have bent the shelves but they were also crap to begin with. To avoid this, I want to dado the shelves into the back and sides with a 3/8 dado cut in the back, 3/4 dado in each side, and a front support that probably will dado into the shelf and dovetail into the sides. That way, each shelf gets support on all 4 sides.

That is one idea but then I found this sawtooth system and having 1.25 in thick support from white oak teeth cut at a 30 or 45-degree angle with a 1.25in thick support slats sounds incredibly strong. Like, that might actually be stronger than a dado especially if I add a 3/4 half inch plywood rod under each shelf and build a little notch for it in the slat.

BTW, I am purposefully overengineering this. I have a lot of books and they are quite heavy. They are also unrelenting weight on an item. I just don't know which is stronger but I do know what is more convenient.

Last edited by bholland; 01-07-2019 at 05:48 PM.
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post #5 of 14 Old 01-07-2019, 07:16 PM
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For anybody interested this is a sawtooth shelf:

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post #6 of 14 Old 01-07-2019, 09:27 PM
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The sawtooth design is cool, but a lot of work. One comment - yes, books are heavy, but the bookcase needn't be. I use 1/4" plywood for most all book case backs, 3/4 is way overkill, PROVIDED shelves are non-adjustable. If you can live with that, shelves can be 3/4" stock, and glued and screwed along the back edge through the plywood, and dadoed into the sides. Pics show the last one I built last year when I ran out of bookshelf space. It's all construction grade lumber, but could have been any wood desired.

The second picture shows how the trim was accomplished. Ignore the waxed paper under the books, it was put there when the wife was anxious to get the books off the floor, and I didn't want the books to stick to the 3 day old paint job. Haven't got around to taking it out yet. Bookcase is 39" wide by 80" tall.
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post #7 of 14 Old 01-08-2019, 07:55 AM
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I used 3/4" to build my bookshelf, but it's also a murphy door so it had to stay rigid when swinging open. The shelves are also fixed.

The sawtooth method (new to me) looks like a lot of extra work just for adjustable shelves, but do indeed look strong.
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post #8 of 14 Old 01-08-2019, 12:45 PM
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Great video. And yes, he lost man points for using his wife's pink garden pads. And I'm going to have to nick him an additional man point for not having manly knee pads to begin with. He may be able to appeal and get a point back for admitting the whole fiasco. When I made two sets of adjustable shelves for bedroom built-ins, I bought a couple sets of the metal rails with removable clip-shelf supports and cut a dado (or groove?) so the rails would fit flush to the surface of the sides of the case. Across the front of each shelf I attached a support brace that fits tight against the face frame on each end. The sides and shelves are 3/4" plywood, the front support pieces (which also hide the shelves' plywood edges) are 1x2s. The front supports make the shelves look heftier and in proportion to the floor-to-ceiling cabinets.

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post #9 of 14 Old 01-08-2019, 12:54 PM
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Quote:
Originally Posted by phaelax View Post
snip

The sawtooth method (new to me) looks like a lot of extra work just for adjustable shelves, but do indeed look strong.
That is part of the appeal as well as strength.
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post #10 of 14 Old 01-08-2019, 01:09 PM
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Quote:
Originally Posted by FrankC View Post
For anybody interested this is a sawtooth shelf: ...
In case anyone cares, sawtooth supports for shelves are a very old idea. Here is a photo of a shelf on a sawtooth support, in an antique wardrobe that we have in our home.
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post #11 of 14 Old 01-08-2019, 01:29 PM
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Another advantage of sawtooth design is with a little modification to the support pieces...you can slope the shelf to display things with an added stop to the front of the shelf (for bins, hand planes, etc).
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post #12 of 14 Old 01-08-2019, 02:21 PM
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Part of the appeal is that there is no metal hardware used and they can be made with only basic tools.
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post #13 of 14 Old 01-08-2019, 05:05 PM Thread Starter
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I like them because I can define a tooth length (say 2in) and the width (say 1.25in) can be double that of a dado. Basically, I can use a miter saw and crank these out very quickly, then either glue or screw them into the sides. I might even do a very simple spline and glue it down for support. I would also do white oak for the wood to match the rest of the case.

I think this settles it. Thanks!

The 3/4in plywood back might be overkill but I can't find white oak plywood in another thickness and this is something my wife will absolutely murder me for not matching. Also, I have had bookcases twist on me really hard, particularly without shelves in them, especially during a move. But really, this is simply the easiest (though not cheapest) approach.
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post #14 of 14 Old 01-08-2019, 07:31 PM
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To Frank C. and all the rest that seem to "like" the vintage Saw Tooth...All I can say is Amen Brothers!!!

Simply put they are awesome, old and well proven in the work they can do from delicate shelves all the way up to Ware House behemoths that have to literally hold tonnage as we had in our supply depot in the Marines.

As to being "...a lot of work..." I kind of love reading that, as it does make me laugh. I mean that respectfully, but I hear it all the time about all manner of thing...from stone foundations to timber framing and (of course) on things like this too!!! AND, it seem to always come from folks that have never cut one in there life, let alone dozens of them...

They are not that difficult to cut compared to what they can do. Whether skilled with a hand saw, chisel or using power tools...once you get into them, they go relatively fast. Last set I made for just some shop shelves I did with a framing square (you could use a "speed square") which I used as a "quick guide" for the saw. I then made all cuts with a narrow kerf batter Makita battery saw. You don't have to go as deep as the ones in the videos at all!!! I did these only 15mm deep!!! These where 2.4m (8)' high shelves and the "tooth" was spaced 40mm (1.5".) These only took about 5 minutes (not that much time in my book) to cut all four "tooth styles" necessary for a 1m (~3') wide shelving unit...

Frankly (no pun intended Frank C.) they are faster to make (in my view and experience compared to other systems) than all that freaking "jigging" and messing around with routers...

I would also note, they are great for students to hone their hand saw and chisel skills with...

A classic system, well proven and aesthetically pleasing...

Last edited by 35015; 01-08-2019 at 07:37 PM.
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