WW cl@ss - fliptop cabinet part 2: Building the carcass

[Bas]

Fliptop cabinet part 1

Note: This is cabinet making 101. If you’ve ever made a bookcase, this is pretty straightforward, but I decided to err on the side of caution and add a lot of detail.

Cutting the panels and joints

The first step is cutting the plywood panels to size. You can find a cutlist in the first chapter. Assuming you stick with the 18” depth, you should not have any problems getting all the parts out of a single 8x4 sheet . For now, I suggest you only cut parts 1-4 (sides, shelves and bottom), and hold off on the drawer- and wing panels for now. Why, you may ask? Insurance! Let’s say you mess up one of the platform shelves. You’ll still have a large enough piece to cut a replacement. Worst case, you now have to use a different material for the drawer sides. I have a lot more 6”x17” scrap than 22”x 18” scrap.

Note that we’ll be trimming the platform panels by 1/8” later in the project, to ensure the platform will spin freely.

Make a dado in the side panels for the middle shelf. You should make the dado 3/8” deep, technically that’s slightly deeper than half of the material (since the plywood is undersized), but it’s easier to measure that way. Especially if you have those wonderful brass router setup bars. I made my dados using the table saw. I don’t have a real dado blade, but I do have a great box joint blade that cuts 3/8” grooves that are completely flat-bottomed. I set the fence, make the first pass on both panels, then move the fence over just under 3/8 and make the second cut, sneaking up until the shelf fits perfectly. You can also make the dadoes using a router and straightedge. Again, keep in mind the plywood is undersized, so use a plywood bit or make multiple passes with a 1/2" bit.

The sides are joined to the bottom via biscuits. Cut #20 biscuit slots in the bottom of the side panel, five per panel. Make sure you put the outside face of the sides down, and reference the biscuit joiner off the table. Cut mating slots on the bottom panel. For a good fit, you want the bottom panel to be a smidgen proud of the sides, so you can sand it flush. The easiest way to do this is to put a piece of sandpaper under the biscuit joiner when you cut the bottom panel slots, so that they’re offset by said smidgen. See diagram 4 below. There is an excellent video on YouTube that demonstrates this technique.



Diagram 4

With the case still unassembled, cut five #20 slots in the top of the side panels as well. The top biscuit slots will be used to attach the hardwood supports later.

If you don’t have a biscuit joiner, you can use a rabbet joint instead. Cut the side panels 3/4” longer, and make a 3/8” wide rabbet along the bottom edge. Next, cut a matching 3/8” rabbet on the inside face of the bottom panel. See diagram 5. You’ll need to do the same on the top, to mount the hardwood supports.



Diagram 5


I prefer the biscuits over the rabbets, primarily because the biscuits help with alignment, and help hold stuff together during the dryfit. There isn't much difference in strength.

Dyfit and assembly of the carcass
Now would be a good time for a dryfit. See diagram 5.


Diagram 5


I found the easiest way to assemble this is to stand one side panel on the workbench (“top” on your left), slide in the shelf, and add the opposing side. Looking from above, you’d have an “H”. Next, put the biscuits in the bottom panel, and from the right hand side bring it against the side panels. Now put in one of the platform shelves to serve as a spacer on the top. This is why we haven’t trimmed down the platform shelves yet, one of them is needed for this glue-up.

Come up with a clamping strategy. See diagram 6. I clamped the two sides together where the shelf sits, using two 24” parallel clamps. (Note: The picture shows the rotating platform already in place. Remember, I was making the prototype, so I built that first to test it.)


Diagram 6


I also put parallel clamps along A-C and B-D, to hold the spacer shelf in place. This doesn’t require a lot of clamping pressure, since there is no glue here. I clamped the sides to the bottom with four 50” parallel clamps, along A-E, B-F, C-G and D-H. If you don’t have parallel clamps, pipe clamps or bar clamps and cauls will work as well. Check the cabinet for square, and make adjustments as needed. You may find you need to deepen the dadoes, or trim a shelf. Make sure the clamps are tight, as tight as you’ll have them for the actual glue-up. A good way to mess up a project is to confirm everything is square with light clamping pressure, then apply glue and squeeze the living daylights out of the project, racking, twisting and tearing everything out of alignment. Take your time with this, and don’t hesitate to use a block plane, chisel, sander etc. to get a good fit.

If you’re using rabbet joints, you should make some 3/8” strips to fill the rabbets at the top, giving the clamps something to hold on to. Tape them in place with some blue tape. You’ll also need clamps along E-G and F-H.

Now it’s time to assemble the carcass. Apply glue to the bottom panel biscuit slots and the biscuits, and glue them in place. Next, spread glue in the dados and put in the shelf. Add glue to the side panel biscuits slots. The easiest way is to start at the top, and squeeze some glue from the bottle into the top slot. Spread it with a brush, and smear whatever comes out down towards the next slot. You want glue on the entire bottom of the side panel anyway. Continue until all the slots are filled. Now assemble the bottom, add the top spacer (do NOT glue this one) and clamp it all up. If you're using rabbets, I'd start with gluing the shelf and then do the rabbets and the bottom.

After you clamp it up, check to make sure everything is square. If it’s not, you will need to fiddle with the clamps to get things to align. For example, perhaps the top spacer isn’t in straight, causing the sides to bend apart at the top. I like to use plastic drafting triangle for this, since there is glue squeeze-out at this point and you don’t want to mess up your combination square. If it’s not completely square, there is no need to panic. The only thing that needs to be truly square is the opening where the drawer will go. The rest has a lot of latitude.

If you’ve made it this far congratulations! This is the hardest part of the construction.

[Bas]

My first assembly (or as Norm likes to say, "assembally") attempt involved yellow glue, a shelf that stuck out and couldn’t be hammered into place, lots of sweating and even more swearing. I knocked everything apart at the last moment, just before the glue had irrevocably set up. I cleaned everything out, took a chill pill and redid the glue-up with slow-setting plastic resin glue. I timed myself, and I managed to get everything together in less than 15 minutes, so yellow glue certainly was feasible. But it’s nice to know you have an hour to fiddle with the clamps. If you’ve never used plastic resin glue, now is an excellent time to experiment. You can get it at Ace Hardware, for about $8. Or come over and borrow a cup of glue powder.

An alternative is polyurethane glue, but that stuff foams like crazy and doesn’t clean up with water. Nasty stuff, but still better than running out of time. If you’re going to go that route, use blue tape mask off all the joint areas, to catch most of the foam. Also consider ordering some Waxilit from Lee Valley. Waxilit looks like paraffin wax, it will prevent the glue from sticking to any areas where applied. When the glue is dry, you can remove both the Waxilit and the glue with mineral spirits. A small tin lasts a LONG time.