I have a silly question after partially constructing a cabinet. How to
figure out the size of the drawer openings and size of the drawers(that
would include slide extensions) the cabinet is made of 3/4 birch ply and
will sit on the floor.
For all the slides I've used you add 1/2 to 9/16 to either side. What I
like to do is split the difference and make the drawer 1-1/16 narrower
than the opening. Make it too wide and you have to plane the drawer
down. Since I use prefinished ply, I don't want to take a sander to
it. It's ply, so I wouldn't plane it. A bit too narrow and you can
easily shim the slide.
Are you talking width, height, or both?
Slides take 1/2" per side. You don't want more than 1/16" oversize on that.
Too tight and they won't fit, too loose and they will not seat properly,
then you have to shim. Make the cabinet first, then make the drawers to
fit. The instructions will tell you the spacings also.
As for height, divide the opening by the number of drawers and allow about
1/8" between. It gets a little tricky if you are making different sized
drawers. In that case, I'd make the deeper bottom ones first.
As for the slides, the full extension ones are just a buck or two more than
the shorter ones. Worth the extra money, IMO, to get the full extension.
The maximum depth of the drawers is likely defined, if you've completed the
Most slides usually require a 1/2" on each side - so your drawer width is
probably a given now too.
That leaves the height and spacing between the drawers. Aesthics drives this
one. Will they all be symmetrical? If not, then you can research some
designs on progressive door heights. It can be an arithmetic or geometric
progression. Fibonnaci, etc.
To answer to your question properly, you must first decide upon the type of
drawer slides you will use prior to building the drawers.
Basically, you design the drawer opening dimensions when you design the
cabinet, then determine the drawer width based on that drawer opening AND
the manufacturer's technical specs for the drawer slides you will use.
As an example, on most Euro side mount drawer slides of the Accuride and
Blum variety you generally make your drawer 1" narrower than the drawer
opening. For undermount slides read the package and see whether they are
mounted flush to the drawer sides, if so, you may have to take the precise
thickness of the drawer side material into account when figuring the
drawer's final width.
In short, most drawer slide manufactures have a technical sheet in the
package that will tell you how to dimension the drawer with their product.
In some cases, like a few of the more expensive hidden, undermount drawer
slides (Hittech comes to mind), the thickness of the drawer side, front and
back material is an important factor in dimensioning the drawer width and
Also beware of drawer _height_ for both undermount slides, and for those
drawer slides where the drawer must be tipped to mount it on the installed
slides, or you might have a clearance issue with the top of the drawer
opening, a common rookie mistake.
Then there are wooden drawer slides that have been around for a few hundred,
if not thousand, years. For a few ideas in that regard, see Page 3 of the
Project Journal on my website below ...scroll down to the "A&C style end
table" for a blow-by-blow with pictures on one method, of many.
I think that's the precise answer the OP needed. I can underscore the
attention to thickness. I recently re-mounted a large drawer in a very old
maple workbench I just purchased. The drawer sides were 13/16" solid maple!
I had to use the router to cut grooves on either side to accomodate the
drawer slides, since I had not choice about changing the existing
Make the carcass first. Be extra fussy about getting everything
absolutely square--if not your drawers won't fit properly or might
bind. Buy the extension hardware before you build the drawers. They
should come with instructions about the clearance requirements and
I'm currently adding drawers to a few kitchen cabinets. Ash sides with Maple
5/8ths Ply for bottoms on "heavy item drawer" and 3/8th's on light duty
ones. As long as the cabinet is square, you then use the specs from the door
slides and add both slides widths and subtract from the width of the ID of
the cabinet. The most important thing is that everything is square,
otherwise you'll be playing for days getting the drawers to work seamlessly.
Don't think that later you can shim or scrape so accuracy can be a "little"
off. You'll pull your hair out trying to figure which side is off in/out,
Of course, the OP could always make drawers without slides. You know,
those Neanderthal things :-). I only use slides for drawers that are
going to hold a great deal of weight or those I want to pull out all the
I really like a Neanderthal drawer where the air pressure from pushing
it in opens another drawer. I've managed to do that a couple of times
and it always brings a big grin to my face :-).
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