Choosing a Standard Method for Cabinet Construction
A supervisor helping a new cabinet company establish its standard production system gets feedback about the pros and cons of many different assembly methods, from a variety of perspectives. July 11, 2013
Question
I am working for a manufacturing company and have been put in charge of the developing a cabinet line for the company. The owner insist that for production that we will not use dados or rabbets, but instead but join all edges using the pocket hole system, and solid 3/4" plywood construction for the whole carcass. I am trying to make an argument for dadoed decks, 1/4" ply backs, in other words, cabinet construction that is more typical of a custom or semi-custom cabinet. I’m having trouble finding a leg to stand on. Does anyone have any comments or ideas that would help me make my argument or his for that matter?
Forum Responses
(Cabinetmaking Forum)
From contributor L:
Depends on what quality standard he wants to sell to. We follow AWI standards. Butt joints with pocket screws won't meet AWI but if your market is residential it probably doesn't matter. Pocket screw joints have low shear values that can be improved by glue in the joint. Still won't meet AWI but you are selling to people that don't care. Put a nice finish on the face and hope the box holds together long enough to get installed. Most likely at that point it will last long enough. If it would make you feel better you could always glue block the bottom side of the floor with a couple of 3" long blocks.
From contributor M:
With the thickness variations in sheet goods that we see today I would avoid going with a full dado. CNC cut blind dado joinery is a totally different story, and I find that it works well but that might not fit into your approach. All of the pocket screw boxes I have seen built with 1/4" backs seem to be reasonably sturdy. With that being said I build blind dado boxes and pocket screws would not be my first choice.
From contributor R:
If you're going to be driving screws, why not confirmats? I use confirmat screws with dado 1/4" backs with a 5/8 nailer behind the back. I hot glue the back in place after assembly. Pocket screws would seem rather slow and require a lot of input from the assembler. How will you align and flush the parts prior to driving the pocket screws?
From contributor M:
Recently I removed a 24" cabinet for a dishwasher and it was of frameless construction with 3/4 back set between the sides just like the floor and stretchers. The sides, floor, and back had 3-4 screws each side and one screw each for the stretchers. I do not know if the back is doweled but I believe the floor and stretchers are. For what it’s worth it is a heavy cabinet. This particular cabinet was full height at 34.5 - no separate toe kick. You could use pocket screws for the back I guess. Don't know about AWI standards.
From contributor B:
I would agree that one of the hardest things you'll face is how you align/register the parts for screwing. Pocket screws shift the parts and a dado/rabbet, as well as adding strength and more glue surface, provide a positive way to register. Perhaps you do the math on the cost of a rabbet/dado with brads or staples that can be shot in rapid fire as opposed to a butt joined box with the cost of a couple dozen screws, the time to drill and run them, and the labor cost of a worker fussing with parts slipping during assembly. A good show would be to head out to the shop, cut two boxes (one each way), and have the owner assemble them or at least watch someone assemble. I would think in the end the winner would be clear.
From contributor X:
There are some things in life that we have to put up with. Your boss wants it done his way, so you do it his way. If he changes his mind down the road, so be it. As long as that paycheck is good don't rock the boat. You voiced your two cents and in time they will change their requirements once again. I have worked for some companies and one that sticks out in my mind was where we made a plywood face frame that was assembled with corrugated fasteners, talk about cheap. He had a name brand store sell his products for him. They sold for decent money. People will buy anything because they know no better. They get what they pay for. It’s your boss’s product and he can do as he wishes with it. Trying to cut costs and corners can come back to haunt all of us.
From the original questioner:
Excellent replies. As I am continuing my search, I am trying to find online copies of the AWI cabinet standards. Does anybody know if they exist on line or only in print?
Contributor X - I think your comments are the most interesting on the side of "suck it up". I would highly agree with that, but if the company is going to look at dollars vs. integrity and stake the company name on it, due diligence is a must prior to committing to an entire line. That way I can at least say, "I told you so" on down the road.
Another comment I received earlier from a direct email response was that this appears to resemble a RTA or knock-down cabinet. That comment has stuck in my head now and that’s not the impression that I want to convey to customers choosing this company line at all.
Contributor L - thank you for your comments on the construction type not meeting AWI. This company want to move towards AWI standards to qualify for some commercial work, and that’s another good selling point.
From contributor D:
To the original questioner: You made a vague reference to commercial cabinetry, hence the AWI standards. AWI has regular chapter meetings in most major cities. Maybe this would be a place to start. There is a big difference between simply following AWI specs and actually being AWI certified. If you are in fact developing a residential line of cabinetry, then the KCMA (Kitchen Cabinet Manufacturers Association) standards are what are typically followed.
From contributor F:
"The owner insists that for production that we will not use dados or rabbets, but instead but join all edges using the pocket hole system." This really makes no sense if your owner is really interested in production rates. The only thing fast about this method is non-use of clamps. If your boss is so hung up on using pocket screws fine, but at least use a 1/8" groove and dado system for alignment.
I've built several ways over the years trying to find the one that suits me best. I started out building just the way your boss wants (makes me wonder if he is inexperienced) because I thought it would be fast and easy. It really is neither. It takes much more time to drill four or five pocket holes than it does to cut a groove or dado, and without any grooves or dadoes it takes more time to assemble and your boxes are not consistent from one to the other. You'll end up having issues with backs and nailers - trimming to fit each cabinet.
This is just really not a production method, by any means it's more of a home shop style of building, which is easy but slow. As I mentioned above, you might suggest using a combination of both methods. Cut shallow grooves for alignment and use screws to eliminate clamping time. In most cases, you can also pre-finish your faceframes before assembly with no nail hose to fill or parts to be clamped.
From contributor F:
From what I gather, we're talking about attaching sides to faceframes, decks to sides, and backs to decks and sides. Building a box for frameless is something totally different. I sure hope someone wouldn't try to build a frameless box with pocket screws! Aligning sides with a faceframe and aligning decks or bottoms to register the faceframe bottom is important to get correct. Slapping a box together with 3/4" ply is fairly straightforward and doesn't necessarily benefit as much from dadoes and grooves. Those of us that build traditional ff cabinets understand that alignment is one of the most critical parts and cutting grooves and does is definitely more accurate and fast than without.
From contributor J:
To the original questioner: So are we discussing faceframe or frameless here? Also please define "solid 3/4" ply" - I'm stumped on that one.
From contributor R:
Faceframe or frameless if you need dado (or think they are time saving) to position/locate or think it's faster you haven't spent much time with the other. I will say if you are using CNC equipment and the dado can be cut quickly go for it but you are losing time and money if you think you need a dado to position a faceframe correctly/accurately/quickly. If you have the CNC and you are trying to take errors out by low skilled assembly folks I can see it.
From the original questioner:
Before this all gets too heated, all of the responses have been helpful. Let me summarize this all. The two most important comments that have come out of this discussion are registering the pieces, and the time constraints.
In regards to the registering of the pieces, that is one of the things that was noticed in the first production run of these cabinets. Reveals weren’t consistent on each of the scribe sides, and gapping was noticed on irregular cuts on the bottom deck and back. Not that the box isn’t that sturdy, but in my opinion, why should we be producing a cabinet carcass in a custom shop that suggests something that a DIY’r could be built in a garage – that’s the appeal I am fighting for.
I have not had time to run a comparison on production times for either construction, so if anybody has performed this with recorded production times, that would also be helpful. I have noticed that the assembly using pocket holes only has been more cumbersome in trying to brace and hold during assembly. Watching them try to work the whole plywood carcass also seems to slow them down because of the weight. The dado construction pieces seemed far quicker when the cuts were all performed correctly and box completion was very consistent. My next step is to present the owner with all of these pros and cons. The hard part is that everyone has made great arguments for both!
From contributor R:
I can teach a DIY'r to build the box either way in a day. I believe you are worrying about the wrong things. Make sure your doors, woodworking parts, and most importantly finishing department are working at top notch speed and quality. Those are the areas where you'll make your money and reputation - or lose them.
From contributor F:
I've been building for about 25 years so I've ran the gamut on all construction methods. In my opinion, good techniques never become outdated and so is the case with wood joinery. As far as your production times, that will all depend heavily on the quantity of your current job, but believe me, cutting dadoes and grooves in FF's and cab sides is not time consuming - 20 seconds for a faceframe and maybe 8 or 10 seconds per side to run dadoes. When everything is complete, you know exactly where everything goes, everything fits snugly, you have more glue area and you don't need any props or gauges to make sure your assembly is correct.
I would incorporate quality in all aspects of your cabinetry, from the box to the hardware, not just what is visible on the front. Besides, the biggest plus for me is you never have to try to hide those ugly pocket holes and if you’re building and leaving them exposed, well, you shouldn't.
From contributor J:
The butt joint pocket screw assembly will require more operator input than the dado or doweled or confirmated box. I built dado FF full dado back with partitions flush with both sides of the frame for the first half of my career, blind dado frameless with full dado back for nearly the second half. Both were a total waste of time. The guys really banking around here with FF construction here just build the frame, dado the ends in the back of the FF, butt joint and face nail the deck, and add a 1x8 at the top back to staple the plastic drawer guide sockets into and attach the guide at the face frame with one #6x1/2" wood screw. Works great until it fails, but no one sees that far out anyway.
No partitions anywhere in between. Bidding against that I normally get my teeth handed to me. I would keep the dado just for registering the parts if doing FF. Just takes the assembler's input out of the equation and provides consistency. I do frameless now off a PTP and horz borer with confirmats. They may be ten years behind the curve, but make an outstanding box, flush and rigid, even before the back goes in. I'm proof that anybody, if it's machined correctly, can assemble the thing and get it right. One day in the not too distant future I hope to move toward a doweled and clamped box, but until I get a case clamp, the confirmats will still get me a good product out the door. "Manufacturing" suggests processes that can be, at some point, performed by automatic or semiautomatic machinery. Otherwise you're just building.
From contributor W:
I am surprised no one has brought up the simple butt joints with staples, #8 1.75" screws, and no glue. I've been using this system for close to 15 years and have been back into many of my past clients houses and have seen no problems with any of the boxes. I changed over after reading the "True 32" book. I use this system for both faceframe and Euro boxes, 3/4" ply or melamine with 1/4" backs set into groove. I've had other woodworkers think I'm crazy for not using glue, but the boxes are screwed to each other and the walls.
From contributor R:
I probably wasn't clear enough but that's my system also, just using 2" #8 screws is the only difference.
From contributor V:
Same here, but I use #14 x 2" screws and no staples. It was real tough until I discovered these dowel/screw things that would align the parts for me. I found that the extra minute to drill pilot holes was well worth it.
From contributor I:
I am a big fan of blind dado construction with assembly marks (thermwood/ecabinets). On non-exposed faces I generally tack the parts together with 18g brads, check and make sure everything is flush, then screw home with 2" spax screws. If I needed to do more volume I would get an industrial PUR hot melt gun, case clamp, and ditch the screws. Once you start cutting boxes on a CNC you will never go back, especially if you are small to mid-sized shop doing residential work. Some larger commercial shops do better with a computerized panel saw, multiple line boring setups, etc., but that is really a different game. It is really unfortunate that I still need to process so much solid wood, because I would sell all of my conventional machinery in a heartbeat to get more floor space.
From the original questioner:
We were able to get everything resolved with ownership and made some good compromises. Thank you for everyone’s help and suggestions. I think the most important thing that we resolved is the registration of the parts themselves using dadoes and rabbets, but we will now be utilizing a 3/4" plywood back for efficiency of materials - a good compromise. We developed a set of standards between the shop and the office that makes a lot of sense. Ultimately, I think now we have a cabinet carcass that we can use for a faceframe cabinet, and a frameless box for a full overlay door. This makes one production style that will help greatly down the road. All fastening will utilize a #8 Promaster wood screw to reinforce the sides and staple to lock the back into a rabbeted joint.
