Cabinet Carcass - Square Pieces but assembly is not?

F

fire7x

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Mar 8, 2020
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I’m using an MFT/3, TS, and guide rail

I’ve got square pieces thanks to TSO guide system, fence dogs and other accessories.

I tried to put together a little cabinet carcass for practice with extra wood and it’s just not square. Being small about 10x15in, it should’ve been dead on.

To make matters more frustrating, I’m using a domino and even setting it to the tightest/snuggest fit, and with the domino, I’m using the domi plate.

Here’s how I dominoed them: I reference the front and back edge with the little retractable notch I did this on all pieces and used the domi plate.

Like I said the glue up just wasn’t square!

Any tips? Being the overall size is small the tolerance should’ve been way tighter and I was expecting near perfection
 
Questions: i) How did you check its squareness during clamping? 2) How much is it off?

Bad news first. Too many things can go wrong that make an assembly out of square. The Domino Joiner may be out and needs calibration, the plunging technique may be off, the boards may be dead square but not dead flat, the clamping is not properly done (e.g. introducing a twist during the process), the square you use is not really square itself, wood can move after assembly, etc. etc.

Good news is that it hardly matters unless it's out of square a lot. We all can fit a door or doors, drawers, etc., in a slightly out-of-square carcass; a lid in an imperfectly square box, or a glass in a less-than-square frame. 
 
Pictures would definitely help. I’ve had the same problem. My latest mis adventure I was completely convinced that I was using the domino referencing off the correct side. I was wrong. I was referencing off the wrong side. I really couldn’t wrap my head around it had to sit down and look at the instruction manuals...watch some videos..when it clicked. Not saying you’re doing that but it is just one example.
If you started out with one completely straight edge and ran a cut directly parallel to it and did the same with the cross cut using TSO guide and a guide rail for example it has to be square. Somewhere along the glue up you probably introduced some error.
 
Make sure the saw shoe is set to 0° . A slight bevel on the edge of the pieces will really screw with you.

Tom
 
I don't think I agree about a smaller case being easier.  I think the opposite is true, the bigger the case the easier.

With the domino I only use narrow-narrow on the mortise close to the front of the case.  I use narrow-middle for the rest on a given joint.  Gives you wiggle room.  To me that's the great value of the domino - wiggle room and strength. 

I never have truly flat plywood and few of the cases are dead square no matter what I do.  Sometimes I get lucky.  You can do a back captured in a dado with enough play to rack the case a little to force it square and then set it with short staples to the bottom and sides. 

If you go with face frames they can also make up for little issues.  With the plywood I have to work with face frames on the wall cabinets are a must. 

But I also never do work in new construction so the rooms and spaces I work in are usually pretty wocky-jawed anyway.  So even if my cases were dead perfect it would still be a challenge.

Test your corners with a true square and your diagonals and if you're in the ballpark it'll go together well enough to get a nice install.

 
You didnt mention whether you put a back on the cabinet?

The back will square the cabinet up.
 
My thought is around what jobsworth said.  Even when all the pieces are square, the dominoes are bored square, etc.  The carcasss won't come together square.  A well fitted back in snug dadoes will bring the carcass right into square. 
 
Today, I dry-fitted my first ever carcass for a desk I am building with walnut plywood. It will be three carcasses with a L-shaped top. I probably went overboard on the number of Dominoes for the project, spacing them about three inches apart. Surprisingly to me, it fit perfectly and square. Definitely, the back pulled it all square. Ready for glueup now.

kOvfO6X.jpg
 
The Great Gazoo said:
Ready for glueup now.

kOvfO6X.jpg
Click to expand...

Remember a dry-assembly that's square is no guarantee that the glue-up is square. Clamping itself can pull it out of square. Make sure you check the diagonals (front and back, if possible) before calling it a day.
 
I don’t know if it matters as much on smaller boxes but assembling larger projects on a dead flat work surface helps a lot. If there’s enough play in your parts the finished assembly has a chance of mirroring any twist or bow in the work bench. Uneven clamping and or over tightening the clamps (already mentioned ) also comes to mind. I’ve been guilty on all accounts...
 
I use a set of black plastic square braces I got at Rockler’s when I do box or carcass glue-ups. If the carcass is big, I clamp the sides to my Woodpeckers framing square. I usually only glue two sides at a time, then join the other half. This process is slower than gluing all four sides the same time, but I don’t usually get any clamping distortions.
 
I've also found, especially for larger cabinets/cases, if you glue it face or back down it is much easier to adjust the diagonals.

Mike
 
Out of square cabinets is a common mistake that is easy to correct during the build process.
[list type=decimal]
[*]Glur and assemble the cabinet. I suggest just putting the glue on one piece of the two being joined otherwise you will have too much glue on the joint. You do need to put glue in both sides of the domino hol
[*]Apply your clamps and just put enough pressure to close any gap otherwise you may bow one or more of the sides.
[*]Reference the image below.
[*]Measure A-C and B-D, they should be the same, most likely not
[*]If one measurement is longer, place a clamp on that diagonal line
[*]Note the difference (I use metric measurements because it is MUCH easier to add, subtract, multiple, or divide with less errors).
[*]After determining the difference, divide the difference by 2, this is the approximate difference you want to tighten the clamp and shorten the long measurement
[*]After you tighten the clamp the desired amount, remeasure A-C, B-D and repeat adjusting the clamp if necessary
[*]After you have A-C, B-D the same lengths check all joints and ensure there are no gaps, adjust as necessary
[*]Remeasure A-C, B-D and ensure they are equal, adjust if necessary
[*]Assuming all is now correct leave all the clamps in place. Remove any glue that has squeezed out, I normally let the glue dry 24 hours.
[/list]
 
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