This article is reprinted posthumously.
In my shop, I use dado blades a lot. So much so that I keep one table saw as a dedicated unit with dado blades in it all the time. I find that, for one cutter, the number of operations I can complete is worth the money and floor space required.
|I use these blades for milling dados, grooves, rabbets, tenons, tounges and grooves (which are the same as a cope and stick for doors and paneling that are craftsman style), to make dental mold, rough out a cove mold and for many other milling applications.|
One of my favorite operations to use dado blades is when I make drawer boxes using what I call the “Quarter-Quarter-Quarter System” (QQQ). This method makes a really nice looking drawer that is very strong and shows lock joint joinery in each corner.
For the system to work, all of the 1/2-in. material must be a true 1/2 in. thick, unlike much of the 1/2-in. plywood on the market today which is as much as 3/32 in. undersize. I like to use 1/2-in. 9-ply pre-finished plywood for the sides, front and back, and 1/4-in. pre-finished plywood or melamine for the drawer bottoms. My customers like the look of the exposed 9-plys and lock joints, and the painters and customers both love the fact that the drawer boxes need no finishing. Also, pre-finished drawer boxes are a must for euro style cabinets, which have both pre-finished drawers and cabinet boxes, leaving only the doors and drawer fronts to finish in the shop or onsite.
I call this system the QQQ system because…
- I use only the outside dado blade plates, which combined are 1/4 in. wide.
- The blades are raised 1/4 in. above the table saw top.
- There is 1/4 in. between the rip fence and the dado blade.
With this one QQQ set-up, I can make all the cuts I need to build my drawer boxes. The cuts I make with this set-up are the crosscut dado for the box joint, the rabbet for the box joint, and the bottom groove for the drawer bottom.
To get started, you need to create the table saw and dado blade set-up using precise 1/4-in. measurements.
As with many of the set-ups on my machines, I like to set the measurements using dial or digital calipers—once you get used to them, they are easier to read and more accurate than a tape measure. Calipers are read in thousandths of an inch, so instead of thinking in sixteenths, eights, quarters, etc., you need to know the decimal equivalent in thousandths. You can use a construction calculator for these conversions or download a handy conversion chart through this link (or click the image, below).
Prepare the material
To start building the drawers, I first determine how many drawers of different heights I need to build, and then I rip one lengthwise slice off the plywood for each height multiplied by the number of drawers for those heights. If the drawers are an average size, you can usually get one drawer from each ripping with maybe enough left over for a side of another drawer. Next I figure the lengths I need to cut off of the pieces for two sides, which are equal in length, and the front and back, which are equal in length.
I generally make the sides 2 in. less than the overall depth of the cabinet box. For example, a standard kitchen box is 24 in. deep so I cut the sides 22 in. long. If all of your drawers are the same depth, cut two pieces for each drawer of the same height, and you are done with this step.
Figuring the widths for the backs and fronts requires more time, since there will be many different cabinet box widths. To determine the widths of these pieces, you need to measure the widths of each drawer box opening, making a list for these widths multiplied by the number of different drawer heights of the same width. You will cut two pieces for each drawer height of the same width.
When you have a drawer bank with several drawers stacked vertically, their fronts and backs will all be the same width, though you’ll probably have varying heights. For these drawers, you can cut two pieces for each drawer height, since they are all the same width.
Drawer part dimensions
The formula for the width of a drawers’ back and front is as follows:
Drawer box opening width – 1 1/2 in. (1 in. for drawer sides + 1 in. for drawer guides) – 2 x the length of the milled tongues (1/4 in. each)
The instructions for your drawer guides will give you the side space required. All of the side mount guides I have used require 1/2-in. space for each side. When multiplied by two, this equals 1 in. I like to use full extension ball bearing slides by Dynaslide, Knap Voit or Accuride—all have the 1/2-in. space per side, which again equals 1 in.
Almost all of the powder-coated euro style slides which I have run across require 1/2 in. per side, too. So I’ve made 1 1/2 in. the default amount to subtract from the drawer box widths to determine the width to cut the fronts and backs. Just check the amount of space the manufacturer requires for the guides you use to affirm this 1 1/2 in. factor.
These days we’re also seeing more concealed drawer guides on the market, such as Blum’s tandem guides. These guides require a different amount of space from the bottom of the drawer to the drawer-bottom groove than the 1/4 in. allowed by the QQQ system.
Understand the lock joint
With your list complete, cut all of the fronts and backs from the pieces left over from cutting the sidepieces. Make sure you keep the stack of sides separate from the stack of fronts and backs since these have totally different milling operations.
With all of these parts cut, you are now ready to mill the box joint corners and the grooves for the drawer bottoms. The sides are easy. They just have a crosscut dado at each end, cut into the inside face of each side.
But the backs and fronts require a rabbet cut, and that cut must be made into the outside face of the front and back.
All of the parts must be cut with a groove for the drawer bottoms.
Follow the milling sequence carefully. Remember, when you’re cutting the front and back, the groove for the drawer bottom must be on the inside face, which is the opposite side of the rabbet!
Start by setting up the dado blades.
|They must be set to cut an exact 1/4-in. wide groove. Use a caliper to check the setup. If necessary, place paper shims between the blades.|
Next, raise the dado set so that it’s exactly 1/4 in. above the table.
|I use a piece of 1/4-in. mdf and a straightedge, then I rotate the blade so that the teeth are just barely touching the straightedge.|
Finally, adjust the rip fence so that it’s precisely 1/4 in. away from the dado blade.
|A dial caliper works really well for this adjustment, but you can also use a piece of 1/4-in. mdf—if it measures exactly 1/4 in. You can check that with your calipers.|
Mill the lock joint
Now you’re ready to cut the joinery. I always start with the sides—they’re easy and I get them out of the way.
|Simply cross-cut a dado into each end. Be sure the inside face of the material is down against the table.|
|Then, also keeping the piece with the dado grooves facing down to the table saw top, cut the length-wise grooves for the drawer bottom.|
Once all the cuts are complete on the sides, set them aside, and bring over the stack of fronts and backs.
|Like I said before, the fronts and back can be a little confusing. The rabbets are cut into the outside edge and the pieces must be held perpendicular to the table saw face.|
It may seem a bit awkward if you have never cut in this position before. But these cuts remove only a small amount of material and you’ll feel little resistance from the machine.
As shown in the photo, apply light pressure to the piece against the table saw fence with one hand, and push the piece through the cut with the other hand. You could also use feather boards to apply the pressure to the fence, which would be safe, as the boards would cover the dado blades.
|Once you’ve rabbeted the sides, lay them down with the rabbets UP, then cut the groove for the drawer bottom.|
|Assembly is really a snap. I apply a light coating of glue to the rabbets and inside the drawer-bottom grooves, then I pin two sides to one back, slide in the drawer bottom, and press the drawer front into place, securing it with a couple pins, too.|
Some folks think that the only way to make a drawer is with dovetail joints, but I’ve never had a QQQ drawer joint fail, and they are a LOT faster to cut, a lot easier to cut, and require far fewer tools!
AUTHOR BIO, written by Gary Katz
For those of you who never met Steve, he was a beloved cabinetmaker and millworker who lived in Southern California. He contributed to some of the top trade magazines, and presented at JLC LIVE. If Steve couldn’t find a tool from his collection to use in building custom cabinets, doors, and windows, he made one. When I looked for a special radius jamb and entry door or a houseful of bifold windows and doors, or the sweetest hardwood kitchen, Phipps was the guy I turned to first. He made some of the finest circle-top sash available, even those fancy radius muntins for Gothic tracery.
But Phipps also invented tools and hardware, and made them right in his own woodworking and metalworking shop. One visit and I could walk away thinking, “This is one scatterbrained genius!” Good luck trying to keep him on a single subject; Phipps’ mind worked on multiple issues simultaneously. He’d be untying the knots on his latest update to the Rok Buk (a door and plywood dolly that became a carpentry cult icon, mostly because it was in such short supply!), but his mind was analyzing the traffic and shop flow at one of his latest creations, like the small manufacturing plant where he planned to turn out Rok Buks, custom miter saw stands (that double as router tables), Simple T-Astragals (with integral extension flush bolts), and who knows what else.
There was no such thing as a quickie when you visited with Steve Phipps. In his Cabinetry Workshop at JLC LIVE, Phipps’ demonstrated his slick setup for milling cope-and-stick joints in cabinet doors—all right on his miter saw stand. He taught cabinetry and tool design, but he also spoke a lot about gardening, classic guitars, deep-sea diving, and Texas, too.
Sadly, Phipps died of cancer a few years ago. His funeral was attended by nearly 1,000 people, many of whom knew Steve through AA—Steve personally assisted dozens of people in the AA program with their recovery.
Every time I build a drawer box using this technique that Steve taught me—and I use it frequently—I can’t help but stop and think about the guy. He was one of the most memorable carpenters I’ve ever met. He had more ingenious and creative ideas than any person I’ve known. His energy was limitless, especially the energy he devoted to his friends and the carpenters who were lucky enough to have met him and learned from him at JLC Live!