Cabinet Material and Design Questions

[Chris McLeester]

I've built cabinets before, but I'm about to embark on a big build and would like to simplify my process. I've read a lot of articles an d forum posts with great suggestions, but I have a few questions related to materials.

1. I would like to use prefinished maple ply for the carcases to simplify the finishing. My normal construction method is a tongue and dado for the top and bottom of the carcase. Would the glue joint still hold with part of the tongue being finished? Would a full dado be better or worse?
2. For doors, I make a simple shaker-style door with a plywood panel. This has been a pain in the past because I have to try to get perfectly centered grooves with two passes of the blade instead of being able to use a dado stack. The resulting doors can also feel a bit flimsy (especially on a large cabinet). I've heard that MDF is true to thickness, but I have concerns about wetness near sinks. I've also never finished it. Any suggestions on what to use? Is thicker ply a better option?
3. Similar to #2, I am at a loss on drawer bottoms. Everything I see says to use 1/4 ply. But the stuff I can find is woefully undersized. Is there a simple trick that everyone knows here and I'm missing? How do you cut your grooves for this or is there some better material. Do you use any clips?

[Jamie Buxton]

My experience is that prefinished plywood is more trouble than it is worth. One issue is that if the surface gets scratched anywhere in distribution or in construction, you're in trouble; there's no easy way to repair it. But the showstopper for me is edgebanding. If you use prefin for the shelves, how are you going to band it? The common answer is PVC "wood grain" tape glued on with hot melt glue. It looks like plastic, and the edge frays in use. Real wood is better, but how do you flush-trim it without scratching the prefin? And how do you finish it without the finish getting on to the prefinished surface?

I know two solutions to your question 3. One is to buy a blade which will cut a groove that fits the "quarter inch" plywood. Amana has an adjustable slot cutting router bit which will do the job. And Forrest has a stacked dado head which will do the job. Either of these tools costs about $150. The other solution is to buy 6 mm Baltic Birch plywood. It really is close to 6 mm (.24").

[Lee Schierer]

Have you considered using pocket hole screws for your cabinet assembly. They are plenty strong. I made this rolling cabinet for holding art supplies. It was to be used in a basement so there was no way to get it down the stairs when it was fully assembled. I made the cabinet complete in my shop, carried the pieces down into his basement and reassembled it. It holds several hundred pounds of poster board and other supplies. The cabinet is made of 3/4" plywood and is 6 feet long.
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[Mark Bolton]

I've built cabinets before, but I'm about to embark on a big build and would like to simplify my process. I've read a lot of articles an d forum posts with great suggestions, but I have a few questions related to materials.

1. I would like to use prefinished maple ply for the carcases to simplify the finishing. My normal construction method is a tongue and dado for the top and bottom of the carcase. Would the glue joint still hold with part of the tongue being finished? Would a full dado be better or worse?
2. For doors, I make a simple shaker-style door with a plywood panel. This has been a pain in the past because I have to try to get perfectly centered grooves with two passes of the blade instead of being able to use a dado stack. The resulting doors can also feel a bit flimsy (especially on a large cabinet). I've heard that MDF is true to thickness, but I have concerns about wetness near sinks. I've also never finished it. Any suggestions on what to use? Is thicker ply a better option?
3. Similar to #2, I am at a loss on drawer bottoms. Everything I see says to use 1/4 ply. But the stuff I can find is woefully undersized. Is there a simple trick that everyone knows here and I'm missing? How do you cut your grooves for this or is there some better material. Do you use any clips?

We use pre-finished exclusively for carcass and shelves and havent experienced the problems Jamie mentions. We arent tender with our parts but we also dont treat them like baboons but the UV cured finish on pre-fin ply (if you buy good stuff) is pretty rugged stuff. Now we have had some import birch in the shop a couple times that is very soft and prone to scratches but we run Columbia or other North American brands and have no issues with scratching.

We use blind dado (not really necessary for us but we do) or rebate construction with glue and screws and the boxes are as rugged as any. If we have a critical or heavy application we will run inset backs with dado's and an applied backer/nailer but that is rare. The edge/ply glue joint in a ply dado/rabbet is very strong when you do a good job with your glue and the screws are just there for clamping and a little added insurance. We use to just pin everything together with finish nails (much faster) but with the CNC its easy enough to pre-drill all the construction holes and screw them and the are rock solid right of the bench with no risk of them racking while being moved around.

We edge band 3/4" Maple ply pre-fin 2 sides for shelves and partitions all day long with no problems of scratching. We use maple pre-fin/pre-glued banding and are still banding by hand and trim with a simple shop made blade (single edge razor blade with backer removed driven into a scrap block of wood) as we never get the edges we like out of the two sided clamp style trimmers. Then just break the edges with a shop made V block and adhesive sandpaper applied.

One thing to remember is that cabinet makers often tend to drastically over compensate on carcass construction when a much flimsier construction schedule would easily do the job for all the years they will be in service and more. Its not to say build flimsy cabinets but when you get into thinking about all these little details its clear that you are well beyond the point of building a cabinet that will fall apart so anything your considering is just improving the structural capacity of the cabinet to a level that will never be challenged.

I would never argue that building your boxes raw and then finishing them in the shop doesnt make a better looking box. We have another local shop that we cut parts for that still assembles this way and the interiors of his cabinets are nearly furniture grade. The corners are all tight and filled with glue, the sprayed finish across the joints is definitely nice. While our corners are dead tight and filled, there is still a line there that speaks to pre-finished sheets. The real issue for me is that NONE of my customers care about the construction details of the box or about the minutia with regards to these details. They care about the stuff they see and interact with daily.

So in the end, he pays about $2 a sheet less than I do for raw maple ply, he still has to be conscious of dents, scratches, and defect, while breaking down and handling material. He is more prone to scratches because he is pushing finished face against shaper/tablesaw, etc. He then has to lightly machine sand everything when done, then blow down, and spray, scuff, and spray again. So for $2 I get all of that done for me ($.0625/ square foot). I cant sand, and spray for that. At $75 a gallon for material I cant even buy the finish for that.

[Chris McLeester]

Thanks for all the thoughts!

Jamie - If you use the baltic birch for drawers, you don't have any issues with just using the dado stack? That sounds like the way to go if so.

Lee - I use pocket holes for the face frames, but like my carcases without them. What do you use for your drawer bottoms? The worktable on that is really neat. I like how you can pull a chair up under it.

Mark - Thank you for the awesome and thorough reply!! When you say "glue and screw" for the dados, do you use regular wood glue? I assume that your blind dados are full thickness and not rabbeted. And does it mean that you drive a screw from outside the box into the top and bottom pieces of the carcase?

I'm all for trying to get the time/money savings you are getting with the pre-finished. What do you mean by the line from pre-finished? Not that people look at the insides of cabinets often.

We use pre-finished exclusively for carcass and shelves and havent experienced the problems Jamie mentions. We arent tender with our parts but we also dont treat them like baboons but the UV cured finish on pre-fin ply (if you buy good stuff) is pretty rugged stuff. Now we have had some import birch in the shop a couple times that is very soft and prone to scratches but we run Columbia or other North American brands and have no issues with scratching.

I would never argue that building your boxes raw and then finishing them in the shop doesnt make a better looking box. We have another local shop that we cut parts for that still assembles this way and the interiors of his cabinets are nearly furniture grade. The corners are all tight and filled with glue, the sprayed finish across the joints is definitely nice. While our corners are dead tight and filled, there is still a line there that speaks to pre-finished sheets. The real issue for me is that NONE of my customers care about the construction details of the box or about the minutia with regards to these details. They care about the stuff they see and interact with daily.

[Lee Schierer]

Lee - I use pocket holes for the face frames, but like my carcases without them. What do you use for your drawer bottoms? The worktable on that is really neat. I like how you can pull a chair up under it.

Typically I use 1/4" birch plywood for drawers that won't see a lot of weight. Though you would be amazed at how much weight you can put on a 1/4" drawer bottom. If the drawer will see heavier items or really heavy use, I go to 3/8" ply, which can be hard to find. My drawer boxes are always dove tail construction and the slot of the bottom is cut on my TS. I cut the slots on all four sides and enclose the drawer bottom on all four sides. I generally don't glue in the bottoms, so that in the event a bottom ever needs replaced you could cut out the back along the bottom to release the drawer bottom and slid in a new one.

That side table will fold down flat against the side and has a second set of supports that fit inside the first set that will tilt it to become a drafting table.
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[Mark Bolton]

Mark - Thank you for the awesome and thorough reply!! When you say "glue and screw" for the dados, do you use regular wood glue? I assume that your blind dados are full thickness and not rabbeted. And does it mean that you drive a screw from outside the box into the top and bottom pieces of the carcase?

I'm all for trying to get the time/money savings you are getting with the pre-finished. What do you mean by the line from pre-finished? Not that people look at the insides of cabinets often.

Yep. Either titebond super or straight tightbond (original). We do qualified dados sometimes (conventional dado but we put a small rebate on the mating sheet to eliminate any thickness variations in the sheet) but again thats a rare one. And yes, software lays out screws with a given distance from each edge and then evenly spaced at a pre-set max distance. So there are screws through the side into the back, side into stretchers or full top, and side into the bottom. Then our backs are rabbeted top and bottom so there are screws through the back into the bottom.

The line I mentioned is just that its pretty much obvious to anyone who knows what they are looking at that the box used pre-finished material. While sometimes you can get a joint dead tight along its entire length and filled with glue more commonly you will be able to see that the two parts went together prior to finishing. We do our best to get the joints filled with glue without it being so much that you make a mess to clean up but its not always perfect. Like I say, a raw built box that is sanded and sprayed after assembly definitely looks nice, we just dont have the customers that are willing to pay for that. They want to shift all their money into the stuff they see and interact with. Revashelf, fronts, doors, and so on. They could care less about the box. You of course want them to look nice, especially on uppers, but for us most of our base cabs now are lots of drawers and pullouts so in a 3 drawer base cab the interior of the box could be dead raw for all they know. They will never see it until they pull a drawer out to clean it (if they ever do). But again, for $2 a sheet, the prefin makes the box just that much nicer.

[David Utterback]

I have some drawers from a very high-end manufacturer. They used short strips of hot melt glue to hold the drawer bottoms-on the undersides, of course.