Dividers for book shelves

[Andy Kev.]

Hello All,

I'm about to start work on a pine bookcase. The individual shelves will be about 5 ft long and I can't see any harm having vertical dividers to support them.

My question is about the joinery: they will obviously connect the top of one shelf to the bottom of another. Would you use simple housing joints or sliding dovetails? The latter would obviously be bomb proof and what concerns me about the former is that they would all be end grain to long grain, or is that not a factor as the role of the dividers is ultimately to provide support to the shelves?

 

[CHJ]

If they are just to reduce 'sagging' of long shelves that are end supported rather than essential structure integrity, why not just make them interference fit.

This would allow small adjustments in lateral positioning to accommodate book sets etc.

EDIT:- If the Bookcase is just a 'functional' unit as opposed to an exercise in wood working craft then dowels would be fine if you need the dividers to be fixed, the joints are in compression and would not even require adhesive.

 

[fuse]

If the bookcase had a back panel you could just screw it to the back edge of the shelves and not bother with dividers
But sometimes its about the journey not the destination.....

 

[Mike G]

...... Would you use simple housing joints or sliding dovetails? The latter would obviously be bomb proof and what concerns me about the former is that they would all be end grain to long grain, or is that not a factor as the roll of the dividers is ultimately to provide support to the shelves?

I've always used housing joints for these. All they're doing is preventing the shelf above from sagging. However, if the shelves are open (ie without a back), and have nothing else to prevent racking, then a more secure joint would certainly help.

 

[Andy Kev.]

Thanks for the replies, gentlemen.

Mike, that's quite reassuring as I intend to give it a back. In my previous attempt at a bookcase (3 ft wide), the back was of 1/2" tulip wood and it was nailed through into the edges of the shelves, so that provided of lot of rigidity, probably more than enough. So housing it is.

 

[Pete Maddex]

I would do a housing joint just for peace of mind it will add a lot of strength.
A couple of triangles of thin ply or metal let into the back and top can be used as fixings into the wall for security.

Pete

 

[AndyT]

I've got a wide bookcase I made about 30 years ago. The shelves are oak veneered blockboard. I don't think you can buy blockboard any more. It was ok for paperbacks but the lower shelves had heavier books on and developed a visible sag.

I fixed the problem by inserting other pieces of oak veneered board which are indeed just a tight fit into the gaps, held by gravity and friction. They've done the job, without needing to dismantle and rebuild the whole thing. So keeping it simple can be ok.

 

[Andy Kev.]

I've got a wide bookcase I made about 30 years ago. The shelves are oak veneered blockboard. I don't think you can buy blockboard any more. It was ok for paperbacks but the lower shelves had heavier books on and developed a visible sag.

I fixed the problem by inserting other pieces of oak veneered board which are indeed just a tight fit into the gaps, held by gravity and friction. They've done the job, without needing to dismantle and rebuild the whole thing. So keeping it simple can be ok.

View attachment 53767

Thanks for the suggestion, Andy but as I am building it from scratch and I quite fancy the challenge of building the dividers into it. I think I'll have a bash at doing it with housing joints, as it will demand bang on marking, which I think is a useful and beneficial challenge.

It will also require me to organise the sequence of tasks sensibly, an area in which I can be a bit chaotic due to improvising if I have a "bright" idea.

 

[Cabinetman]

My thought was that why not build it with a vertical divider and half length shelves?

 

[Jonathan]

I’m with Ian on this one, I always try to design with the shortest span possible to illuminate sag

 

[AndyT]

I think I agree. Also, if you design it with a continuous line of vertical suports all the way up, and want to joint them all into the shelves, you could be in for a very challenging glue up.

I'd go so far as to say that the common approach of making most of the shelf positions adjustable isn't because you ever need to adjust the shelves once it's built. The bigger benefit is that you don't have dozens of bits to glue at the same time.

 

[Jonathan]

Most of the library’s I’ve been commissioned has had adjustable shelves,
If it’s a painted finish is soo much easier to finish and lighter to move about.
I always try to put a 10mm back on, naturally this is fitted after spraying/finishing.

 

[Richard]

My thought was that why not build it with a vertical divider and half length shelves?

I'd do exactly the same, but add the ability to make the shelves adjustable with shelf pins, or similar, e.g., tonks. It would make the construction logical and simpler. As to the shelves, it's true that once set up they're rarely adjusted again, but it can happen, I've done so a few times, and it's good to have that future flexibility. Slainte.

 

[Andy Kev.]

Thanks for the central divider idea. I'll have a good think about that.

Shelf adjustment will not be a matter for me, because the size of my books will dictate the spacing. For instance the bottom shelf will be the highest for the bigger books. Most of the rest are hardbacks and they demand a shelf gap of about a foot. I've actually not measured this in inches because I will let the size of the book plus a sensible gap for making it easy to get out, be the factors which dictate everything else.

 

[TrimTheKing]

I’m with Ian on this one, I always try to design with the shortest span possible to illuminate sag

I imagine there are plenty on here who would much rather their sag remain very much un-illuminated...!

 

[Richard]

Thanks for the central divider idea. I'll have a good think about that.

Shelf adjustment will not be a matter for me, because the size of my books will dictate the spacing. For instance the bottom shelf will be the highest for the bigger books. Most of the rest are hardbacks and they demand a shelf gap of about a foot. I've actually not measured this in inches because I will let the size of the book plus a sensible gap for making it easy to get out, be the factors which dictate everything else.

As a by the by, typical book shelf loading is ~11kg per 300 mm shelf length, roughly the same as 25 lbs per 12" (foot) length. This applies to 'standard' books, e.g., a mix of paperback novels and textbooks along with typical hardback novels and textbooks. Large format books, such as it seems you might be dealing with, are usually worth getting out the bathroom scales for and establish from that what your typical loading might be.

After that, if you're so minded, you could get into some Deformation in Pure Bending stuff along with flexure formulae to calculate how much sag your shelves might develop over time. It's all a hoot I can tell you, or could just make your shelves out of something decent and thick enough (i.e., not 12 mm chipboard) to start with, and perhaps screw through the back panel into the rear of each shelf, ha, ha. Slainte.

 

[Andy Kev.]

My shelves will be 3/4 inch pine, so if I do go for the central divider, I imagine that sagging will not be a factor.

 

[Phil]

My 2 bits.
1500mm is a very long shelf to have books/weight on without support.
The couple I built was max 500mm with dividers every 500mm, using 20mm pine boards between 200mm to 300mm wide.

This popped up the other day on one of the feeds.

Bookcase Dimensions: Height, Width, and Depth Explained

Bookcase dimensions usually range from 10–12 inches deep, 24–48 inches wide, and 36–84 inches tall. Learn how to choose the right size for your room, ceiling height, and books.

belleze.com

 

[Dr.Al]

Have you seen this website @Andy Kev. ?

The Sagulator – WoodBin

I've never used it but it seems to be a useful tool if you're making shelves.

 

[Spectric]

You could be creative and make the dividers thicker and mimic a book.

 

[Cabinetman]

Now that’s an outside of the box idea!

 

[Spectric]

Maybe I should patent it, these could be sold with a custom book tittle on them.

 

[Jonathan]

Back in the 90s we used to buy custom book splines to decorate false panels within a bookcase, don’t know if they exist now.

 

[Andy Kev.]

Have you seen this website @Andy Kev. ?

The Sagulator – WoodBin

I've never used it but it seems to be a useful tool if you're making shelves.

Thanks! That really is most useful and interesting. It turns out that my plan is well within acceptable limits.

Have we got a "resources" bit of the forum where that could be linked to? I'm sure I'm not the only one who would benefit from it.

 

[Andy Kev.]

My 2 bits.
1500mm is a very long shelf to have books/weight on without support.
The couple I built was max 500mm with dividers every 500mm, using 20mm pine boards between 200mm to 300mm wide.

This popped up the other day on one of the feeds.

Bookcase Dimensions: Height, Width, and Depth Explained

Bookcase dimensions usually range from 10–12 inches deep, 24–48 inches wide, and 36–84 inches tall. Learn how to choose the right size for your room, ceiling height, and books.

belleze.com

Thanks Phil. That's another very useful resource. I had to grin at the illustrating photos though as not one of them was showing something which was functioning as what I would regard as a book case i.e. stuffed full of books.

 

[RogerS]

Digressing slightly. Who remembers the lovely cleaner, who six years ago during lockdown, during a deep clean decided to resort the books on the shelves in Newmarket library by height rather than by title or genre?

 

[Lons]

Digressing slightly. Who remembers the lovely cleaner, who six years ago during lockdown, during a deep clean decided to resort the books on the shelves in Newmarket library by height rather than by title or genre?

Wasamarrawithat?