Project Working

Youll need 2 sides, one top, one bottom, one back, one or more shelves and one or more doors. 

Unlike my other posts, there is no cut list or cut plan because these are general instructions and the size of the cabinet will vary based on your needs. Instead Ill provide information on how to calculate the dimensions of the components youll need to build your own cabinets to your specifications.

The type of material you choose will depend on where you will be installing the cabinets. In your kitchen youll want to use nicer material than in your garage.

The cabinet box is also called the carcass. The thicker the material you use, the stronger the cabinet will be and the longer you can make your cabinets. 3/4" material is recommended but in some situations 5/8" or 1/2" can also work. Some woodworkers use different thicknesses for different parts of the carcass such as 1/4" backs inserted into a groove with 1/2" nailing strips, or 1/2" for the back and sides and 3/4" for the top and bottom. This is mainly done to save money. If youre only building a few cabinets for yourself you can simplify the process and wind up with stronger cabinets if you just use the same thickness material (3/4") for all the components.

Plywood is better than MDF is better than particle board. If youre using plywood its important to note that plywood comes in different grades. One grade for the good side and one grade for the back side. A1 is the best appearance grade of plywood you can get. If you want to save some money you can choose to build the carcasses out of a lower appearance grade plywood such as B2 and use the A1 plywood for exposed ends and doors. Some even like to use melamine coated particle board for the carcasses with better plywood for doors and end panels. If you plan on painting your cabinets the grade of the plywood isnt as important. 

For shop cabinets in the basement or garage you might be able to find "shop grade" plywood at your local lumber mill. This plywood would have more defects in the veneer but still have a strong core. Many people even build shop cabinets out of CDX plywood. Its not very pretty but the X in the name indicates the glues used can handle a bit of exposure to weather which could be good in a garage.

If youre going through the trouble of building your own cabinets youre already saving a considerable amount of money and it makes sense to go with plywood in most instances. For the purpose of these instructions Im going to assume the cabinet will be built with 3/4" plywood.

You can make plain slab doors out of the same material you use for your cabinet carcasses. In our case plywood. This will be the cheapest option and the one Ill be using in this guide because there are too many options and methods to construct cabinet doors to discuss here.

If youre not happy with a plain slab cabinet door a number of companies will make custom doors for you in a variety of styles at reasonable costs.

Step 1: Calculate Cabinet Component Dimensions

Before we begin cutting and assembling our cabinet we first need to determine what size cabinet we need. If youve ever gone to a kitchen showroom youve probably noticed that the semi-custom cabinets they offer come in some standard sizes. Since were building our cabinets we can choose any custom dimensions we want to suit our needs. There are some limitations however. The material and thickness chosen will decide how wide a cabinet we can build. In most cases with 3/4" plywood about 42" should be the maximum width but narrower cabinets will have more stability.

Standard upper cabinet depth is 12" (including door) when over a counter. Deeper when over a refrigerator and has more support. The 12" upper cabinet depth leaves a 10-1/2" interior depth. Dinner plates are usually 10" in diameter but can up to 12". If you have larger plates, or want to leave room for larger plates in the future, make your cabinets deeper. In our tutorial well build a frameless upper cabinet that is 18" W x 30" H x 12-1/2" D. This will leave an 11" interior cabinet depth.

Our cabinet will be made up of 6 pieces of plywood. 2 Sides, a top and bottom, a back and a door. All will be cut from 3/4" plywood. To determine the size of each component well use the following formulas.

(For consistency the "height" is also the direction of the grain.)

There are 2 sides and in most case the dimension runs vertically. The height of the side is the same as our desired cabinet height. Because were using overlay* doors the width of the side is our desired cabinet depth minus the thickness of the door.  In our case we have:

Side height = 30" (height of cabinet)

Side width = 12-1/2" - 3/4" (depth of cabinet - width of door) = 11-3/4"

Well need 2 11-3/4" x 30" pieces of 3/4" plywood.

(Overlay doors sit in front of the cabinet. Inset doors sit within the cabinet. For inset doors the width of the sides will be the same as the width of the cabinet.

The top and bottom pieces have the same dimensions. The width of the top/bottom is equal to the depth of the cabinet minus the thickness of the door. The height of the top/bottom is the width of the cabinet minus the thickness of each side.

Top/Bottom height = 18" (cab width) - 2 x 3/4" (side thickness) = 16-1/2"

Top/Bottom width = 12-1/2" (cab depth) - 3/4" (door thickness) = 11-3/4"

Well need 2 16-1/2" x 11-3/4" pieces of 3/4" plywood.

The back of our frameless cabinet fits in between both sides and the top and the bottom. To determine the width of the back we need to subtract the thickness of each side piece. To calculate the height we subtract the thickness of the top and bottom pieces.

Back height = 30" (cab height) - 3/4" (top thickness) - 3/4" (bottom thickness) = 28-1/2"

Back width = 18" (cab width) - 2 x 3/4" (side thickness) = 16-1/2"

Well need 1 28-1/2" x 16-1/2" piece of 3/4" plywood.

Adjustable Shelves Dimensions

Depending on the height and purpose of the wall cabinet you may want to have one or more adjustable shelves. These are peices of 3/4" plywood that rest on shelf pins which are inserted in a series of shelf pin holes inside the cabinet.

The shelf is the width of the inside of the cabinet and extends from the back of the inside to 1/4 inch from the front.

Shelf height = 18" (cab width) - 2 x 3/4" (side thickness) = 16-1/2"

Shelf width = 12-1/2" (cab depth) - 3/4" (door) - 3/4" (back) - 1/4" (space) = 10-3/4"

Our cabinet only has one door and we are designing the cabinets to be full-overlay. This means that the door sits in front of the cabinet and covers almost all of the cabinet. In reality the door needs a little bit of space around it to prevent it from rubbing against adjacent doors or walls. 

The minimum space with most hinges is 1/16" so we need to subtract 1/8" (2 x 1/8") from each dimension. That will also give us a nice 1/8" spacing between doors from other cabinets too. 

Door height = 30" (cab height) - 1/8" = 29-7/8"

Door width = 18" (cab width) - 1/8" = 17-7/8"

If we were building a wider cabinet that required 2 doors we would still subtract 1/8" for the height but the width of each door would be (CabHeight - 1/4")/2. There would be a 1/8" space between the two doors and 1/16" space around the perimeter.

Now that we know what size pieces of plywood we need we can begin assembly.

Should you use glue? Pocket hole joinery is pretty strong but glueing the joints in addition to screwing will give you a stronger more rigid cabinet. If you do decide to use glue, first assemble the cabinet without glue to make sure everything fits and lines up well. Then disassemble and reassemble with glue.

Edgebanding: Apply edgebanding to the edge of each of the 4 pieces that will be on the front of the cabinet.

Start by drilling pocket holes in the Top and Bottom pieces as shown and attach the Top to one of the side pieces.

Now attach the bottom to the side. Make sure the pocket holes are on the outside of the cabinet.

Attach the last remaining side, making sure everything is aligned properly and square.

Double check to make sure the back of the cabinet is square and make sure it fits inside the back of the cabinet. If not, make adjustments to the back.

If everything fits together properly, is the right size and is square, disassemble the cabinet and repeat Step 2 above, this time with glue before inserting the back.

Drill pocket hole screws around the perimeter of the back and attach it to the rest of the cabinet as shown using glue.

Because were using pocket screws weve built this entire cabinet without a single clamp. Normally a lot of long, expensive bar clamps are used when building cabinets or other furniture to keep the cabinet in place while the glue dries. One of the benefits of using pocket hole joinery is the screws act like clamps to hold everything together while the glue dries.

Slide the shelf pin jig up to the top of the cabinet, keeping it flush with the front of the cabinet and drill holes for the top hinge mounting plate in the 2nd and 3rd holes from the top as shown. 

Now place the indexing pin in the bottom hole of the jig, slide the jig down to insert the indexing pin in the 1st Shelf Pin Hole drilled previously and continue your way up the side of the cabinet drilling shelf pin holes. Stop before you get to the pilot holes for the top hinge mounting plate.

Flip the shelf pin jig around and place it in the back corner of the cabinet so the short end of the jig is closest to the back as shown. Drill the 1st shelf pin hole in the last hole from the bottom. (We dont need pilot holes for the hinge in the back.)Then continue drilling the remaining shelf pin holes along the back using the indexing pin.

Repeat this step on the other side of the cabinet.

On the back, hinge side of the door, mark 2 lines 3-3/16" from the top and bottom of the door. This is the center-line for the hinge bore.

Follow the instructions that came with your hinge boring jig (such as the Rockler Jig It Concealed Hinge Jig) to drill the 35mm bores for the cup end of the hinge. 

Finally attach and adjust your hinges so the door has an even overlay all the way around the cabinet.

Insert some shelf pins, and your shelf and the cabinet is done. Paint and prime, or stain and finish.