This section is from the book "It's Fun To Build Things", by W. T. R. Price. Also available from Amazon: It's Fun To Build Things.
We might as well start with the easier kind, which are built in wall-recesses. Here the location is an advantage, because the side walls hold our creation up. When we build a freestanding cupboard we are building a piece of furniture, and it has to be built so that it won't collapse or fold up if someone should chance to brush against it in passing.
When a cupboard is built in a wall-recess, the first thing to remember is that plaster walls are all too likely not to be true. This wouldn't bother us unduly until we came to fit the doors, and then we would be faced with a bad situation. Doors, like drawers, have to be square and true or they won't work.
With this thought haunting us, we carefully measure the width of the recess, at various levels. If it is of absolutely uniform width, to 1/16 " of an inch, or even 1/8", the whole proceeding is fairly simple. If not, we'll have to plane the door-jambs until their two inner sides are perfectly plumb.
First, a sound proceeding is to build a base that will clear the base-molding of the room, as in that first recess-bookshelf we built. Now there must be two uprights to which the doors are hinged. Cleats nailed into the wall at the height of the cupboard will give one nailing for these uprights, as well as a rest and nailing for the top of the cupboard. The sketches on the next page give some idea of the procedure here, and immediately following. Two more cleats at the base give a nailing for the lower ends of the uprights, which should also be toenailed into the cupboard floor. The top may now be made ready, with a cleat on its underside, set back to make a stop for the doors. Now the trick is to set the uprights perfectly vertically, since otherwise it will be a heartbreaking job to get the doors to fit, if they can be made to fit at all.

At this critical juncture a carpenter would use his spirit-level, stood on end, or a long steel square, but if you haven't either of these aids, use anything you can find that you believe to be square- (it wouldn't be a bad idea to test it) such as a small drawing board or something of the sort. A picture frame is necessarily square, unless it has been knocked crooked. Another device is a plumb line, hung down from the top of the cupboard, which you may place on its supporting cleats for this purpose. With the plumb line you may mark, both top and bottom, the position in which to place the uprights.
These may be 3/4"x 2", or x 3" strips, and are fixed in permanent position, truly vertical and at right angles with the base, by nailing down through the top of the cupboard and toenailing into the base and against the two lower cleats. This sounds complicated, but a look at the sketches on the next page will be reassuring.
You now have a square opening, and are ready to build a door, or a pair of doors to fit it. If the opening is more than 20" wide, you had better figure on two doors. A wider door puts too much strain on light hinges and works them loose. Then you have a door which sags every time you open it, and constitutes one of life's minor afflictions.

A page of sketches implying the fun of building a cupboard in a corner recess, with hardware suggestions.
There are two ways to build a cupboard door without getting involved in cabinet-making. Real cabinet-made doors, of course, are made with mortice-and-tenon construction, which is both strong and neat. The simple door is made of several boards, held together by cleats. If you build it this way, the cleats should be beveled with the plane on sides and ends, with a 1/4" bevel. There is also the flush cleat type, which can be nailed into the ends of the boards with long finishing nails, it is a simple matter to rip two strips, about 11/4 wide, with the saw. (So far we have used stock sizes only, and done no ripping.) This makes a better door, and one less likely to open at the joints if the lumber shrinks a little.
The other type of door, lighter in weight, is made so that it resembles a paneled door, though it is not built as cabinet-makers build a paneled door. A frame is made, true and square, to exactly fit the opening (or half the opening's width, if there are to be two doors). According to the size of the door, this frame may be made of 3/47" X 2" strips, or, if greater strength is required, 3/4"x 3" strips would be used, especially cut to nail as shown in one of the sketches. (All three types of door are shown, keyed "A," "B," and "C") The panel is simply a piece of plywood or masonite affixed to the inside of the door with small nails or screws.
Now to fit it. Any door should be made a little full (it's safe to allow 1/8"), and planed down to fit. Carpenters always do this, because they know from experience that a door can't be made to fit exactly, without planing. All house doors come from the mills definitely oversize, to be planed down to fit the door openings as the opening is actually built. There is no difference in principle between a house door and a cupboard door, so the cupboard door had better be made a little oversize, and planed to fit. There isn't a thing you can do about it if you make it a little undersize.
 
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