Case Construction Methods
Thoughts on the benefits of dadoes and screws for cabinet carcase assembly. December 10, 2007
Question
Over the years I have changed case construction methods on face frame cabinets, and wanted to get some opinions on what works best and is most accurate and fast. I have done dado/rabbets on cases and pocket screwed the face frames on. I have built cabinets around the face frame using the tongue and groove (accurate but time consuming, no dados on case).
I have read here that some are dadoing the stiles with 3/4" dados, but not the rails. That obviously means that the cabinet sides are wider than tops/bottoms depending on dado depth. That would seem a little time consuming considering you have to cut different widths for sides.
I am spinning my wheels wondering if there is something out there that may be better. I have a sliding panel saw without dado capability. On the outfeed of the slider I have a router with a lift that I cut dados on (sheet goods only).
I could see using the tongue and groove for stiles/sides only, and using dado/rabbets for bottoms, tops, and partitions. I may try this on my next job unless I hear anything better. I liked the tongue and groove method for alignment because everything fits nice and tight, and also leaving a small reveal on the face frame to trim route. I just don't want to have to dry fit a cabinet to get the bottom/top measurement. I like to just go off of a cut list. If anyone with a similar setup would like to chime in, I will appreciate it.
Forum Responses
(Cabinetmaking Forum)
From contributor F:
No similar method, but I will chime in just the same. I have always preferred having no "through the face" fasteners, so I have done a lot of clamping with cauls to spread the clamping pressure. I have never seen any need to use dados on the back of the face frame for alignment, because it just seems so simple to flush the top of the bottom rail to the top of the bottom shelf, as well as flushing the edge of the stile to the outside plane of a finished end... Two flush points, perfect alignment, square carcass. It goes without saying that this is only possible if the parts are square and accurate and the wood in the face frame is reasonably straight.
As far as dados and/or pocket screws, I see them as redundant. Take a scrap of plywood or even particleboard or MDF and apply a good coat of yellow glue to the edge. Clamp a scrap of face frame stock to that edge and let the glue dry. This will never come apart, so why would a dado or pocket screws make any difference?
Time, I suppose, is the main reason for the screws. Dados, I suppose, are used by those who don't flush stiles to finished ends or use "plant on" finished ends, etc. I am developing a new method to eliminate the clamping. I lay the face frame back side up on a flat bench and let the weight of the carcass apply the pressure as the glue sets. I may have to add a bit of weight for shallow cabinet carcasses such as 12" deep wall cabinets.
From contributor P:
Your new method has one big drawback. That's when somebody bumps into the box and doesn't tell you. I was doing a small table, built like a face frame cabinet about 2' x 2' x 22", just a couple of weeks ago, and didn't feel like pocket screwing the frame on, so I just turned it over and put the granite top on the box for weight. Well, there's this kid from the beauty shop next door that comes over to borrow my son's bike from time to time. Apparently, as he was pushing the bike out, he bumped into the table, failing to inform me. I didn't realize the problem until the following morning when I went to check on my glue-up. This is a good example of why the redundancy of the mechanical fastener makes sense for some of us.
From contributor F:
I think that's a good example of how a once in a lifetime event causes the creation of a permanent unnecessary policy. Come to think of it... That must be some sort of standard criteria for OSHA when they write a new rule! Yellow glue has very fast tack under pressure...1 5 minutes and you will need a crowbar. Besides that, ain't nobody here but me!
From contributor A:
Therein lies the problem. You have no one to blame but yourself after you inadvertently bump the box. A lot of people used to clamp and glue frames. I know older cabinet guys who have piles of pipe clamps kicking around. Most people use the pocket screw method to eliminate the need for the pile of clamps. I've never really seen the benefit of dados unless you are building cabinets on the mass scale. They use the dado so they can get away with thinner sheet goods and blind staple the box to the frame.
From contributor E:
I do prefer a dado over just a butt joint. The only reasons being the alignment and ease of assembling. I guess a simple jig could be used for alignment, but it just seems like a better fit for me to use dados. As far as the face frames are concerned, I do pocket screw them onto the box rather than face nailing or clamping. Everything gets hidden by an applied panel or is skinned, even the bottoms of the wall cabinets. So it seems that you guys are not dadoing the face frames, just applying the face frame to the box, right?
From contributor F:
Exactly. After the glue sets, it isn't coming off, dadoed or not. I hear alignment stated a lot as the reason for dados. Hard for me to understand. Lining up the face frame to where I want it to be in relation to the carcass is one of the easiest tasks I do. All the work is already done during layout and part cutlisting, which makes it easy. All of these systems work to make a strong connection. I am just thinking that if I refine my "no-dado-no screw-no-clamp" method, it's got to be less work and less time for an equivalent joint between the face frame and carcass edges.
From contributor P:
If you have to rebuild one box out of every fifty because the face frame moved, then you'd be wasting as much money as had you simply fastened the frame on in the first place. I think you'll be rebuilding more than one in fifty, though. But, as always, do what contents you.
From contributor F:
I can't really remember the last time I had to remake anything, much less a whole cabinet. Just a mindset, I suppose. When things are "in glue," I pay attention until I know I no longer have to.
From contributor T:
I prefer a very shallow dado (3/32) on the backs of my frames and 1" pocket screws. The dadoes are only for alignment. The screws are only for clamps. Once it's connected, it's not moving no matter how long it takes the glue to dry or who bumps into it.
