Bookshelf joints

[Alan Tolchinsky]

Hi All, I'm making a small book case about 31"W x 32"H. I'm using 3/4" plywood and wondered what kind of joining method you've used for this. I have pocket screws but am trying to avoid metal fasteners. How about rabbit joints and glue only? Thanks

[Jamie Buxton]

The big issue with bookcase sturdiness is racking. If you put a back on the bookcase, that will take care of the racking issue. It will also be a big gusset helping to hold the shelf joints together. You can also tie the shelves to the back to help prevent sagging. With a back in your design, you can use just dadoes and glue at the ends of the shelves.

[Mike Heidrick]

You could do sliding dovetails. A magazine I just read showed the jigs to make them.

[Greg Sznajdruk]

Will the case have adjustable shelves or fixed shelves?

Greg

[Alan Tolchinsky]

Just a couple of fixed shelves Greg. Since this is a small unit I'm not doing any adjustable shelves. Thanks!

[Paul Demetropoulos]

A rabbet and dado would be an excellent choice for this project, and good practice.

You could run a 1/4" dado in the bookshelf sides, then rabbet the shelves to fit into the dados. To make the strongest joint you would orient the tongue of the rabbeted shelf end so it's flush with the underside of the shelf, much stronger under a heavy load than if the tongue were on the top.

As mentioned a back makes it much stronger and prevents racking. Make sure your back is cut square and use it to square up the project during glue up.

[Mike Heidrick]

Why not make the dado the same thickness as the whole shelf and insert the whole thing.

[Wade Lippman]

Why not make the dado the same thickness as the whole shelf and insert the whole thing.

Absolutely. It would be foolish to rabbet plywood needlessly. (However, if the plywood isn't a consistant thickness, than it wouldn't be needless.)

[Alan Tolchinsky]

A rabbet and dado would be an excellent choice for this project, and good practice.

You could run a 1/4" dado in the bookshelf sides, then rabbet the shelves to fit into the dados. To make the strongest joint you would orient the tongue of the rabbeted shelf end so it's flush with the underside of the shelf, much stronger under a heavy load than if the tongue were on the top.

As mentioned a back makes it much stronger and prevents racking. Make sure your back is cut square and use it to square up the project during glue up.

Thanks for all the suggestions. I saw Paul's idea in a book. I like it because you wouldn't have to worry about variation in plywood thickness. Now if I could only get a clean rabbet on plywood. It seems I get a lot of tear out when I do it.

[Joe Scharle]

Or you could go with some stair tread and use Sliding DTs and make it a knockdown.

http://www.ncwoodworker.net/pp/data/989/DT_Bench1.JPG

[Joe Chritz]

Dados and glue. It doesn't take long to set up a stack dado blade to match plywood and it is very strong and simple.

You could use biscuits, pocket screws, sliding dovetails, dominoes, dowels, rabbits and I am sure a bunch of others as well.

With the small case I may be incline to just use biscuits since it is easy and weight shouldn't ever be a factor. You can make a story stick to line up the markings and clamp it to the sides as a fence for doing the slots in the sides.

Joe

[Paul Demetropoulos]

Absolutely. It would be foolish to rabbet plywood needlessly. (However, if the plywood isn't a consistant thickness, than it wouldn't be needless.)

I agree with you Wade that we wouldn’t want to do anything needless or foolish. I disagree however that rabbeting the shelf end is either of those things. As you said, plywood is inconsistent in thickness and setup is required to match the dado to the plywood thickness. Using an undersized plywood router bit may or may not match the ply thickness. It’s just as easy to do one pass with a ¼ router bit for the dado in the side and machine a tongue to match in the shelf end.

Now we have an exact fit for the plywood and the tongue and dado joint has the added advantage of a shoulder that resists racking, which a full thickness dado does not. So see Wade, it’s not foolish.

If Alan wants the easiest and fastest joint without using metal fasteners then biscuits would be the answer.

Note to Alan: If you do decide to use the tongue and dado joint, a 1/4" deep dado is plenty. The more material you remove from the bookshelf sides, the weaker it will be.

[Alan Tolchinsky]

I have to admit I hate playing around with a dado set trying to get a perfect match to the plywood thickness. I find it easier though to to match the shelf tongue to an existing dado joint by creeping up to the dado width.

[Alan Tolchinsky]

Or you could go with some stair tread and use Sliding DTs and make it a knockdown.

http://www.ncwoodworker.net/pp/data/989/DT_Bench1.JPG

Hey Joe, That looks really good and sturdy.