Newbie question about bookcase design
 

I'm building a bookcase with four fixed shelves (plus the top). It
will be a total of 50" high and 30" wide.

The shelves will be sliding "half-dovetails." I've _tried_ to
illustrate below what I mean, but basically think of a dovetail with
only one angle cut in. I got the idea out of a design plan I bought,
but the plan was more of a Craftsman-style bookcase with slatted sides,
and I want solid sides.

The bookcase is being built out of flatsawn cherry (YOU try finding
rift/quarter-sawn!), and the sides will be a total of 12" wide.

So here are my two questions:

1. Because the wood is flatsawn, the grain patterns are harder to
match-up, so I would like to glue-up two 6" boards, rather than three
4" boards. I am doing this for the sides and the shelves. Because
this is flatsawn, am I setting myself up for problems with cupping/etc?


2. The reason I'm doing the half-dovetails, instead of simply dadoes,
is that I want the sides of the bookcase to be held together by the
shelves themselves. I am NOT gluing the dovetails, but rather pinning
them in the front to allow them to expand freely toward the back of the
case. However, am I running the risk that, because I'm using flatsawn
boards, that this whole thing is literally going to pull itself apart
over time?

Thanks for any help you guys can give...illustration is below.


| |
| | Shelf
| _|_________
| |
| |/|_________
| |
| |

You should be fine. Cherry is pretty stable. You identified and fixed
the one big problem by pinning the dove tail, even though it is
actually not an opposed grain situiation so the side and shelf should
expand together.

One help for cuppng is to try and get boards that have the grain lines
running as close to perpendicular to the face as possible, ie close to
quarter sawn. Also, glue up the boards and let them settle for a few
days. If any of them cup, just rip them down and re-glue.

Another somewhat radical idea, but it could be a nice effect, would be
to bread board all of the pieces, sides and shelves. One advantage of
this would be on the shelves you would be cutting your modified
dovetail groove with the grain as opposed to cross grain. However, I
would use and extra deep tennon to ensure you get good structural
conformance from the shelf.

Sounds like a cool project.

BW

wrote:

2. The reason I'm doing the half-dovetails, instead of simply dadoes,
is that I want the sides of the bookcase to be held together by the
shelves themselves.

Why not use full sliding dovetails? Easier and double the grab :)
______________

I am NOT gluing the dovetails, but rather pinning
them in the front to allow them to expand freely toward the back of
the case. However, am I running the risk that, because I'm using
flatsawn boards, that this whole thing is literally going to pull
itself apart over time?

It will be fine. Would be too if you glued them (I would) as any
expansion in the shelves and ends is in the same direction. For that
matter, you could dump the dovetails - half or full - and just glue
shelf tenons into side dados...assuming the dados/tenons are a decent
fit the sides aren't going to pull out.

--
dadiOH
____________________________

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On 3 Oct 2005 08:01:56 -0700, wrote:

I'm building a bookcase with four fixed shelves (plus the top). It
will be a total of 50" high and 30" wide.

The shelves will be sliding "half-dovetails." I've _tried_ to
illustrate below what I mean, but basically think of a dovetail with
only one angle cut in. I got the idea out of a design plan I bought,
but the plan was more of a Craftsman-style bookcase with slatted sides,
and I want solid sides.

The bookcase is being built out of flatsawn cherry (YOU try finding
rift/quarter-sawn!), and the sides will be a total of 12" wide.

So here are my two questions:

1. Because the wood is flatsawn, the grain patterns are harder to
match-up, so I would like to glue-up two 6" boards, rather than three
4" boards. I am doing this for the sides and the shelves. Because
this is flatsawn, am I setting myself up for problems with cupping/etc?


2. The reason I'm doing the half-dovetails, instead of simply dadoes,
is that I want the sides of the bookcase to be held together by the
shelves themselves. I am NOT gluing the dovetails, but rather pinning
them in the front to allow them to expand freely toward the back of the
case. However, am I running the risk that, because I'm using flatsawn
boards, that this whole thing is literally going to pull itself apart
over time?

Thanks for any help you guys can give...illustration is below.


| |
| | Shelf
| _|_________
| |
| |/|_________
| |
| |

There should be problem with your plan. Traditionally, these would be
dadoed and glued without any problem of expanding/contracting as there
is NO cross-grain at these joints! It may be helpful to study grain
directions so that you know exactly where to be concerned.