I have always wanted a door that was disguised as a bookshelf. A few years ago, I bought and renovated an old farm house. But there were a few things that I just hadn't gotten to - such as putting a door on the closet in my office. Well my 'office' never had a door, and has since moved into the spare room, so that I can convert my old office to a nursery for a first child. My wife kept saying I could keep my stuff in the closet, but I really didn't think the baby needed to keep my power tools. My wife also kept saying how we needed to get a bookshelf and I kept thinking about how I needed to put a door on the closet....and when those 2 ideas merged, I knew we were on to something! So in the interest of not procrastinating (that due date seems to be coming faster and faster every day!), I decided to get on it and make an Instructable in the process. Enjoy!

So let's get started on the design.There are 4 parts to a HIDDEN bookshelf door (HBF).

1 - the bookshelf: a complete bookshelf that could stand alone and you could be done with it.

2- the frame: this attaches to the bookshelf and connects the door the doorframe.

3- the latch: there are number of options for this. The latch you use determines what your options are for opening the door.

4- hinges: these need to be hidden, which either means you shell out some money for a fancy hinges or you get creative....I was going to use hidden hinges for cupboards, but I decided I wouldn't want to have to do the hinges again if these broke, so I bought proper hinges.

Before you get your own supplies, you'll need to measure your door opening and the desired depth of the bookshelf. The list of supplies that I provided is for a door that is 28-3/4" x65-1/4" x 29" x 65" (my house doesn't have a square angle in it!) with a bookshelf that is 8 inches deep.

Supplies

(2) 1" x 8" x 8'
(2) 1" x 4" x 8'
(4) 2" rigid casters
(1) Latch
(2) Hidden hinges
(4) flat brackets
(1) Backing, your choice

Other things:

Screws
Drill Drill
Driver
Saw
Measuring Tape
Pencil
Paper
Calculator

Step 1: Measure and Draw Up Your Plans

If you want to use hidden hinges, the you can't just build a bookshelf and shove it in the door frame.

The bookshelf has to be narrower than the frame. See image for the details. But basically, a straight line drawn from the front-most-corner on the hinge side to the back-most-opposite-corner of the bookshelf, must be equal to or less than the ACTUAL width of the door frame. If you don't account for the depth of the bookshelf, you're door will not swing open.

Time to break out your trig skills!

Sin(angle) = O/H

O = the depth of your bookshelf, including the thickness of the frame

H = the smallest width of your doorframe

Solve for the angle. Sin^(-1) = arcsin

arcsin(O/H) = the angle

Plug this angle into Cos(angle) = A/H and solve for A.

A = the max width of the bookshelf

cos(angle)*H = A

My numbers:

arcsin(8.5/28.75) = 17.197 degrees

cos(17.197)=A/28.75

28.75*cos(17.197) = A = 27.465"

THE MAX WIDTH FOR MY BOOKSHELF IS 27.465 INCHES.

I personally thought this was cutting it too close, so I made my bookshelf 24 inches wide.

Now we will measure all the pieces that will need be cut.

Bookshelf:

shelves (your choice on how many you want, I chose 3) (these can be the same width as the top and bottom pieces, which will help reduce the number of unique measurements)
top
bottom
sides

In total 5 pieces of the same length and 2 pieces of the same length.

Frame: The frame is the EXACT size of the doorframe. You want this to be a snug enough so that it doesn't look like it opens.

top
bottom
side 1
side 2

In total 4 pieces.

Step 2: Cut Your Frame Pieces and Assemble

Have you double checked your measurements? Good! Now you need to the cut frame.

Cut the pieces. I labeled each board, so I knew which side of the frame it was for and which side faced inside - In this picture it says TBR = Top, Back, Right. This was imperative for getting it to fit again, since my door frame is not square.

Try fitting it together in the door frame and make sure it is a good close fit. Duct tape (not masking tape, I tried that and it failed) may work to keep the pieces together for this, otherwise, you can use a nail gun and put it together loosely with a few brads.

Stick it right in. Does it fit? Good!

Is it too big? Then sand it down or cut new wood if needed.

Is it too small? Then the easiest thing is just to cut new wood.

Ready to connect the pieces permanently? Let's go!

You can connect these 4 pieces however you'd like, but for my purposes, I used brackets.

NOTE: I decided to leave a small, quarter inch or so, gap because the floor isn't level. Eventually I am going to rig a piece of quarter round that will be able to move up and down when the door moves so that the gap is always concealed.

Step 3: Cut Your Bookshelf Pieces and Assemble

Cut your bookshelf pieces.

Pre-drill your holes to avoid splitting the wood. I used 2 screws on
each side for each shelf/top/bottom piece. And I applied wood glue to ensure a strong hold.

You can countersink but only if you want a cleaner look. I chose not to do this, since this is hidden unless the door is open.

Pre-drill your hole before inserting the screw and screw together the top, bottom and sides of the bookshelf.

Now let's put in the shelves...

Step 4: Install the Bookshelves

To measure your spacing (See calculator pic for details):

take the height of your bookshelf and determine how many shelves you want (I did 3)
subtract the thickness of the top and bottom, and each shelf (mine were 3/4" thick each). This will give you your open space.
Determine how you want them spaced. My wife wanted them equally spaced, so I divided this distance by 4. Which ended up being around 14-1/4". Then I spaced them accordingly.

NOTES: Measure early and often. Measure before you put in every screw. Always measure starting from a securely screwed reference point (i.e. don't measure from one unscrewed board to another unscrewed board)

Step 5: Put Wheels on Bookshelf

Attach these with screws. 2 wheels on each end, just off the center line. I was only going to use 2 wheels but then decided to use 4. This made it easier to work with too, since the bookshelf was able to stand up on its own (although it was a bit wobbly).

NOTE: If your house is as un-level and un-square as mine (#GottaLoveOldHouses), make sure you take that into account when attaching the wheels. I put the bookshelf in the frame and made sure my shelves were still level. By some miracle everything was level, but if it wasn't, I was prepared to add washers between the wheel screws and bookshelf base where I needed to get it level.

Step 6: Attach Frame to Bookshelf

There are a number of ways to attach this well.

I chose finishing nails. I know I'd have to go in and cover these up later, but it was much easier to deal with.

To do this, I had my wife help. My wife got in the closet and pushed the bookshelf tightly against the frame while I used a nail gun to attach the frame and the bookshelf. I put the FIRST nail in a TOP corner, SECOND in a BOTTOM OPPOSITE corner to help stop it from shifting as I put more nails in.

Step 7: Put Backing on Bookshelf

There was no easy way for me to cut this without a table saw. I put the big piece of wood on top of my garbage and recycling bins and then measured the width and height and of the bookshelf and cut it out...carefully. It went well enough.

Then I centered it on the back of the bookshelf and used my nail gun to attach it.

Step 8: Attach Hinges

Here are the hinges that I ordered. Their weight limit is not as good as I would prefer, but I don't plan on this door being opened that much or having that much weight on it. That said....

With the bookshelf in the doorframe, hold the hinges on the seam between the bookshelf and door where you want them. I did about 1 foot from the top and 1 foot from the bottom. Mark a line for the location of the screw holes on both doorframe and bookshelf frame.

Next, take a drill-bit that is slightly smaller than the width of the hinge. Measure the depth of the hinge that will go into the frames. Then measure that on to you drill bit - place a piece of masking tape on your drill bit so you know how far in to drill. In my case there were 2 different depths, so I had to do this part twice.

Once you've drilled, use a wood chisel to clean on the inside. This part was tedious. And I had to go back in and drill multiple times. But I eventually got them to fit properly.

NOTE: If your hinge is wider than your bookshelf frame, you will need to get creative. You could get a strip of wood and screw and glue it the bookshelf frame so you have more width to worth with. That said, I would not trust that to be a very strong hold if anything were to get tweaked the wrong way.

Step 9: Create Latch

I may come back and add this to my Instructable, but for now I haven't decided how to do. For now, the frame is very snug and keeps the entire thing in place quite nicely.