Attaching legs and structure strength

allen levine

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this is a rough drawing of a cabinet Im going to build shortly.
The drawing is not to scale, since the paper wasnt wide enough.
The top will be approx 66 inchs long, about 21-22 inches wide, 3/4 inch solid wood.
The legs will be 2 and 1/4 inch square, about 19-20 inches height.
The legs will not be directly on the cabinet sidewalls(sapele plywood)
I colored the part I have a question about.
Im not asking anyone about the design itself. Attaching 3-4 inch spacers between the legs and sidewalls, I want to make sure the spacers are attached so the cabinet weight, the solid wood top(also resting on the leg tops) and the contents of the cabinet(mostly dishes and glasses) will not be overwhelming.
My plan was to cut a 1/4 to 3/8 inch mortise into the sidewalls, predrill through the spacers and wall, and drill into the legs, which will also have a mortise and tenon joint at the connecting point. I was going to run 5-6 inch lag screws into each hole(2 holes on each spacer into each leg) from inside sidewalls, as well as glue the joints.
Will this work well enough for the cabinet and expected weight?
Does anyone see any significant design flaw?(not caring if you like it or not, just worried about the structure strength)
Any suggestions on how to mortise out a 3/8 depth, 1x2 inch approx mortise area in the sidewalls?
Im open for suggestions, not on design, only only structural strength issues and any basic joint issues.
Thankyou for anyone taking the time to understand what Im posting.(the pink areas are the 3-4 inch spacers, about 3 inches in height also)

(again, the drawing isnt to exact scale)
 

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Allen, since the legs will be from 2 1/4" stock, I "think" that if the spacers are made from 2" thick stock and you use a large washer on the inside of the side of the case under the head of the lagscrew, I "think" it should work. As to making the mortises in the case sides, I would make a jig from mdf or other and clamp it to the case side and use a router to make the mortises. I like the design.:thumb:
 
hey allen if i got this right you want to hang your inner cabinet off the 4" spacers that connect to your legs and the top will support someof thweight as well? how are you going to pick up your connection for the weight to the top?
 
The top of the cabinet will not be solid plywood. The sidewalls and inside 2 walls(with dadoed shelves) will be adjoined at the top with a solid piece of 3-4 inch wide wood.Front, middle for support and back-back also will be to support the cabinet back. The top will be attached to these top outer supports with simple table top fasteners, allowing for expansion and contraction of the top.
The ends of the top will just rest on the top of the legs., but the bulk length of the entire table top surface will be held down with those little "z" top fasteners.
 
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The supports between the side walls of the main cabinet and the legs are attached to the middle of the legs, and will be attached to the face of the side walls. Nothing will come out of the back of the cabinet, it will be attached directly to the side of the leg and the corresponding side wall face.Ill make a quick topview diagram.
no laughing, this is a very rough drawing, looking down through the top
I hope this makes my intentions clearer
 

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were this me, i would use the screws to attach to the sides of the cabinets, but i would also use a heavier mortise and tenon joint in the legs, not less than 1/2" thick and 1 3/4" deep, for support, and (my own preference here) use figure 8 table irons to secure the top to the case, using at least 6, to even out the load.
 
IN the legs I was going to use a deep mortise with glue, but wanted to to bolt it through for complete support. There will be no stiles or rails on the cabinet sides, only the face frame.

the figure 8 are fine, but I liked the last ones I used, the table top fasteners, I was able to use the biscuit cutter to cut the slots, very easy, very simple, no mess, and I could even put one in the top of each leg to hold secure the top.
(I have alot of them left)
 
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I think I'd be tempted to use steel tubing or pipe through those spacers with bolts throught the tubing so that the wood itself wan't bearing all that weight. Then maybe a faux through wedged tenon cap to cover the hardware on the outside of the legs?
 
interesting support idea. But Id prefer to have nothing protruding from the legs. I was thinking 3/8 lag screws going 1 and 3/4 inch into 2 and a 1/4 inch thick mahogany would be able to hold a decent load.
The top itself would be mostly supported on the top of the legs. My concern is that the plywood side would not be able to handle the load. I was thinking of adding a half inch strip of wood inside, or maybe even a thin small steel plate to distribute the weight load over a larger surface area.(then I have the problem of not being able to countersink the large head of the screw into the inside of the cabinet, so it doesnt interfere with any glassware inside,
 
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Allen, I think you might run into some structural issues if you suspend the cabinet between the legs in this fashion. Do I understand correctly that the cabinet will not be also hanging from the top?
 
no, just attached to the legs.
Then I think you might have issues with sagging. That will be a lot of weight to place on those shallow joints, how much depends on what you intend to store in the cabinet. Would you consider running the back attachment all the way through the case? This might make for shallower drawers/ cabinet, but it would help a great deal to support the cabinet's weight.

Just my $.02:wave:
 
this has really gotten me to thinking now...:rofl:

to eliminate the possibility of sag, increasing the thickness of the back (3/4" plywood, rather than 1/4" plywood) would give it increased stiffness. another idea for attaching to the legs is making the width of the face frame, to allow a brace running front to back. hope that helps...
 
I thought 2 pieces 1 and 3/4 wide would go under the bottom face frame at 2 spots near center and also screwing in the back all around would support the bottom without any sag.The cabinet length would run somewhere around 51-52 inches approx. With a width of approx 18 inches, I thought the 2 bottom supports(mortised into the back of the bottom rail of face frame) and the back screwed in would eliminate any sag problems. The weight load will be limited to what it can hold, the top not adding any stress to the cabinet sides since it will be resting on top of legs also.
Im beginning to think I might have to run the bottom supports under the cabinet to eliminate any problems at all. It just wont look like I intended.back to the drawing board.
 
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so IM thinking if I build a 2 inch wide frame with plenty of cross supports and 3 lengthwise supports, then attach the bottom over that, and make the bottom rail cover the 2 and 3/4 inches so the bottom support frame is not noticed. That should take the sag problem out of the picture.:huh:

my son told me I can always build it the first way I thought of and if I hear dishes and glasses crashing down one night, I designed it wrong.
 
al, this is the quick version of what i was thinking about. hope it helps...
 

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