Dadoes for Cabinet Case Construction

Cabinetmakers explain why they like dadoes. October 27, 2008

I have switched construction methods a few times and have seemed to always come back to a dado joint. First off I build faceframe cabinets and use pocket screws on the frames. I currently am cutting a groove on the faceframes and a tongue on the plywood. I assemble the faceframes first, then cut down the plywood, put the tongues on them and then assemble on the frames. I am also using dados for all sides and partitions.

Each kitchen I do I contemplate on leaving out the dados but just don't like the looks of a butt joint. There just seems to be too many little gaps that I can't get rid of no matter how tight I crank the prefinished 3/4" ply that I use. What methods are others using and am I just too worried about a little gap here and there? Also I use 1/4" backs with 3/4" cleat placed behind the backs. Any suggestions?

Forum Responses
(Cabinetmaking Forum)
From contributor M:
You keep coming back to dado construction because it is absolutely the best. I have used it for years after trying them all.

Dadoes completely make up for the time they take to cut by how much easier they make cabinet assembly. They also make cabinets stronger and more attractive on the inside, as you note with regard to "gaps" here and there with butt joints. Another benefit is that they open up a raw wood surface to glue to if you are using prefinished or melamine cabinet body parts.

I do frameless cabinets and always use dadoes; I do not bother to go the blind dado route. It only adds complication with, I think, no improvement in appearance. When using melamine, I always run dadoes backward (climb cut) on a table saw to produce chip-free dadoes.

From contributor R:
I use dado joints too. Assembly is fast and looks good. I build mostly frameless and use blind dados. All are cut on a CNC. On face framed I have never tried dadoing them. Just seems like too much time for machining. We used to pocket screw, glue and clamp the frames onto the boxes and again too much time. I recently bought a waffle stapler to attaching the frames from the back and it seems to work great.

From contributor M:
There’s nothing wrong with your dado/grove idea on face frames but why the tongues on the sides? Either just make the dado/grove to fit the 3/4 side or do a rabbet. If you are going to use 1/4 backs try attaching the back with a rabbet and setting the 3/4 cleat inside the cab. If you do make the cleat as wide as your drawer openings are high and attach the drawer runners to the cleat also back will sound better if it is tight to the wall of the house.

From contributor J:
I build similar to you and have tried, on occasion, to use butt joints. I wasn't happy with the outcome either. The dados register everything and make the box go together so much easier. I'm like Contributor M; I don't see why you need the tongue on the case side. Wouldn't an appropriately sized dado on the stile alone accomplish the same thing?

From the original questioner:
To me it is easier to cut a 1/4" groove in hardwood than a 3/4" groove. I have a Slider that is not dado capable so I cut the grooves/tongue on a router table.

From contributor M:
The 3/4" cleat that you mount behind your backs, if you attach it to the wall without attaching it to your cabinets; you then have a ledge on the wall to hang your upper cabinets from. They hang from the lip formed by the cabinet top and you don't have to struggle to hold the cabinets where you want them before screwing them to the wall. You then cinch the cabinets into place by putting a few screws through the 1/4" back into the cleat.

From contributor M:
Your idea about the uppers hanging on the top is interesting. If done that way how do you shim the uppers if wall is not plumb? You would also need a pretty good joint between the sides and the top since the whole cab would be hanging on the top. The other part that I don't get is the cab would only be attached to the wall by the 1/4" back. I can see how it could be a very fast way of doing it.

From contributor R:
I would not use a 1/4" back to hold a cabinet on the wall. I can see the screws pulling through that. I do build with a 4 x 3/4" nailer recessed in the back. I then add a 4 x 3/4" nailer to the wall, 4" down (for the whole run), making it plumb and level, notch all the wall cabinet sides and hang them. I do screw through the nailer attached to the cabinet into studs.

From the original questioner:
That kind of sounds like a French cleat correct? I have a cabinet jack that I use to hand the uppers. This works great and got the plans from this site to build my own. I often contemplate not dadoing the faceframes and just attaching them to cases with pocket screws. My methods have very little tolerances for error which sucks because it takes time. This calls for building faceframes, then building the cases and then attaching the frames to the case. Sounds easy enough, seems to be the way I did it when I first started. I don't know sometimes you hear of a method that sounds great but just doesn't work out for you. I have a full kitchen of faceframes with grooves already cut in them so I have to continue the same way for now.

From contributor M:
You do have to make the top-to-partition connections very secure, but perhaps not as bomb proof as you think. Since I not only dado in the 1/4" back but pin it at an angle from the back side, the back is unitized to the other cabinet members, and some of the weight of the cabinet is transferred to the back panel itself. So the cabinet top is not the only point carrying the weight.

Also, since almost all the weight of a 12" to 15" deep upper cabinet is straight down, it matters little that you are holding the cabinet to the wall cleat only through a 1/4" back. The screws through the back mainly only have to keep the cabinet on the cleat. These screws do hold up some of the cabinet weight, as I said before, buy that weight is carried at a right angle to the axis of the screws.

I make frameless cabinets in modules. The wall-mounted cleat system allows me to assemble cabinets into long runs on the wall, so I don't have to use a helper or some hoisting contraption to lift an already-assembled group of modules.