## table leg design......

Suppose i want to make 4 table legs from aluminium square tube.......how should I go about designing the dimensions of the square tube? The table itself needs to support a load of 90kg through the four legs.

Help on this would be very much appreciated.

Cabellos
 PhysOrg.com engineering news on PhysOrg.com >> PNNL-developed injection molding process recognized with emerging technologies award>> How soon could car seats enter the 3-D comfort zone?>> NASA: Austin, calling Austin. 3-D pizzas to go
 Recognitions: Gold Member The tubing sales people, or at least the manufacturer, can tell you what sort of forces various ones can handle. Then just divide the total weight of the table by 4 to see what size you need to handle it. I'd add at least 50% to the estimated table weight as a safety factor and to compensate for any weakness introduced through your work on it, such as mounting holes. It will also have to stand up to lateral forces, particularly at the attachment points, in case the table gets pushed sideways.
 Recognitions: Science Advisor Metal product manufacturers are most likely not going to tell you anything other than material allowables. They won't tell you anything in regards to how much of a load something will allow. That is the designer's job to calculate. You need to determine the load distribution and the resultant forces on each leg. You need to then calculate the stresses induced based on an initial guess of what the cross section will look like. These will be combined stresses that include the bending moments as well as compressive stresses and buckling. Compare the calculated stresses to your desired failure criteria and revise the design until the stresses are below the desired levels.

Recognitions:

## table leg design......

 Quote by Danger I'd add at least 50% to the estimated table weight as a safety factor...
I would also add about 600 lb, to handle the case when a 300lb man stands on top of the table to change a light bulb or whatever (double the weight of the man to allow for the dynamic stresses when he gets on and off the table). Best to assume all that force goes down one leg, if he is standing on the corner of the table...

Finding the REAL design load cases is the first important step in any stress analysis!

Recognitions:
Gold Member
 Quote by FredGarvin Metal product manufacturers are most likely not going to tell you anything other than material allowables. They won't tell you anything in regards to how much of a load something will allow.
Strange... I've never had any trouble with the local machine shop, where I buy raw stock, advising me as to exactly what sort of material I would need for a particular project (and it's an engineering firm, not just toolies). Maybe it's the difference of living in a small town.

 Quote by AlephZero I would also add about 600 lb, to handle the case when a 300lb man stands on top of the table to change a light bulb or whatever (double the weight of the man to allow for the dynamic stresses when he gets on and off the table). Best to assume all that force goes down one leg, if he is standing on the corner of the table... Finding the REAL design load cases is the first important step in any stress analysis!
I can see why you're not the one who took over my comedy badge this year. Cabellos isn't building a freeway flyover here; with a 90kg load, it's something like an entertainment unit or a cot. While I don't for a second dispute that your expertise in this matter far exceeds mine, I can also will full confidence say that on this scale 50% over-building has never failed me. Also on this scale, that amount of over-building adds very little to the cost.

Recognitions: