Here's one for the structural engineers on the Wreck:
In the fall I'll be taking an intermediate/advanced woodworking class
at the community college. I've been sketching ideas for a chest of
drawers for our master bedroom. Actually, it's two mirror imaged,
interlocking pieces (think of the Chinese yin-yang symbol), but for
our purposes here think of a casework 84" long by 24" deep by 32"
I had been having trouble coming up with a base/foot/leg design that
worked with the rest of the piece. Then it occurred to me: why not
"float" it on the wall, hanging it off a pair of French cleats,
leaving a comfortable 3-4" toekick space underneath?
Here's my structural question: How much does a 7 foot long chest made
of hardwood and full of clothes weigh? And if I have a pair of 3/4"
hardwood cleats screwed to the studs in the wall will that hold it?
What size screws? How much stress is being put on the casework itself
since it's not being supported from beneath? And, most importantly,
what sort of design considerations do I need to take when I build it
to withstand those stresses?
Any thoughts will be appreciated.
It could be done if you have a 6" thick steel-reinforced concrete wall to hang it on.
I assume you do not have that. Therefore I would never attempt it with a normal
tubba4 stud wall. Why don't you just go with feet hidden from the front and sides?
Would that harelip the county?
Speaking strictly from ignorance... this sounds a lot like the standard
structure of upper kitchen cabinets. Perhaps not the French cleat, but
the loading would probably be lower for clothes than for china.
A couple of 3in screws in each stud sounds OK to me.
Since you've probably got this thing drawn up to scale and have a
list you can calculate the cubic inches of each part
L(inches) x W (inches) x Thickness (inches) = Cu In /1728 = Cu Ft
so 84" x 24" x 3/4" = 0.88 cubic feet
x 2 pieces (top &
1.76 Cubic Ft
34" x 24" x 3/4" = 0.33 cubit feet
x 4 (left,right & two in
1.32 Cubic Ft
84" x 32" x 3/4" = 1.17 cubic ft
x 2 pieces (front &
1.34 Cubic Ft
Total Cubic Ft = 5.42 call it 5 1/2
X 35-45 pounds/cu ft
Throw in another 20% or so for drawer sides, guides etc
and you're looking at
*** 230-290 pounds without clothes ****
If the wall studs are on 16 inch centers AND you hit
them just right, the cleat on the wall will be in 5 studs,
each carrying about 50-60 pounds.
On the case side more info is needed. This thing going
to have a 3/4 ply back? If so, how's it going to be
attached to the piece and accomodate wood movement?
If this is a two parter that's 115 - 145 pounds per unit
If each is hung on it's own cleat per your the Yin/Yan
description neither will hit all 5 studs - and each may
only hit 3 studs but there could be overlap so the weight
could be over the equivalent of 6 studs, or 40-50 pounds
=================== <--- upper unit cleat
==================== <---- lower
I'm assuming you've got dry wall on the studs so you
want the cleat on the wall to be at least a couple of
inches wide to a) distribute the load on the dry wall
so it won't crush and b) let you put two screws in
They do make metal french cleats = lower profile
same or better sttrength than wood. In europe
kitchen cabinets are often hung on metal french
cleats - makes remodeling easier and you can take
your cabinets with you when you move.
How wide do you want the cleat(s) on the wall to be? If
you only have room for one screw go big, if three, go
Since people lift things by their top, and lean things back
to get under them - most traditional joinery - dadoes,
dovetails, finger joints, mortise & tenon, splines etc.
that sort of abuse adequately. I'd skip rabbeting//rebating
because of the open end thing.
Should be enough info to get you thinking through your
problem and coming up with answers.
Good luck and have fun!
ps - if you dovetail the top and bottom to the sides
PUT THE PINS ON THE TOP AND BOTTOM AND
THE TAILS ON THE SIDES (or you could have
things fall apart - DAMHIKT)
<snip a bunch of 7th grade geometry that pretty much answered my
question in detail>
Wow, Charlie, thanks for all the help. I'm sorry I didn't respond
earlier but I access the newsgroups through Google and they hadn't
updated in several days. A few caustic e-mails and they seem to have
fixed the problem. Anyway, your contribution was great.
As for joining the sides and top, I wasn't planning to go dovetails,
but rather oversized box joints that are also pinned (think Green &
Greene brothers for inspiration). When I looked up your final acronym
I FOOMCROTFLMAO. But let me ask this, do you see a problem with my
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