Scribing NYW cabinets

On last year's New Yankee Workshop, Norm built cabinets with what looked like about an inch of scribe material on the sides (that is, the side edges went beyond the 1/2" back by about an inch). The 1/2" backs were to be screwed directly to the wall.
I'm not well versed on scribing techniques, but is the idea here to remove most of the scribe material so the sides meet the wall tightly, while the back is as close to the wall as possible?
I would think that a space between the back and the wall would cause a screw to deform the back (think of a screw pulling the back toward the wall as the screw is drilled into the cabinet back). I imagine the ideal spacing between the wall and the back where the screw goes would be zero.
-Does one need to consider such a gap when cutting the scribe material? -How much "gap" is ok for screwing through the back to the wall? -Does one have to shim the gap between the back surface and the wall where the screw goes? (I can't imagine that would be easy to do.)
Thanks for any input, Chuck
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wrote:

Hi Chuck, While I'm not sure what Norm did in this case as I'm not familiar with this particular episode, I can say that 1/2 scribe allowed in this way would not be excessive. It's not uncommon for slight irregularities in the wall on a long run of cabinets to approach that amount. As for being able to shim behind the cabinets, if your placing your screws near the top and bottom of the cabinet then it would be very easy to place the shims where needed (provided the cabinet didn't go right to the ceiling) simply reaching over the top to place the shims where needed along the top edge. The underside would be even easier to get to.
HTH Lenny
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And a little extra space at the back makes for a much neater French cleat installation, one of the more popular cabinet mounting processes.
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wrote:

Opps, sorry Chuck, I read that wrong. I thought it said 1/2" of scribe. I would think 1" would be way overkill. I wonder if there was something else going on with this design? The only other thing I can think of is it's sometimes easier when cutting to a sribed line to be removing more ... that is it's just as easy to cut 3/4" off then it would be to try to cut 1/4". Does that make any sense?
Lenny
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Perfect sense, Lenny--thanks.
Also: I mistyped. The cabinet backs were 3/4" ply--not 1/2".
The scribe material on the sides *looked* like an inch, but then again, sometimes the camera will fool you. (Fools me, anyway.) I guess the extra scribe would allow for the saw blade, when back-cutting (angled in towards the cabinet back) to not cut into the back. I suppose the trick is to keep the circular saw depth 3/4" plus a scoach when back-cutting close to the plywood back.
So, let's assume a perfectly flat wall, with your suggested 1/2" scribe left on the sides, resulting in a 1/2" gap between the back and the wall no matter where the screws were placed. Would such a gap between the cabinet back and the wall where the screw goes in cause the back to bow towards the wall, stressing it? Would the screw have reduced weight- bearing effectiveness?
(I would think if a 1/2" back were used, it *would* show bowing, though.)
These might be academic questions, given ply's strength, but I'm curious. I've just always though intuitively that the best strength is gained when two surfaces of the screwed members are in contact, and when there is no gap to allow the screw to torque under the weight of the outer member (in this case, the cabinet itself).
Thanks again, Chuck
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CMiller wrote:

Shimming is certainly preferable but if the back (or nail board) is reasonably stout one can get away without it. One simply doesn't tighten the screw to the point of deforming the back/nail board excessively...the screw will hold the cabinet even if there is a gap.
--

dadiOH
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