When to consider a tubular structure

[dibakar]

Hi! I am very new to forging and metal works. As a DIY project 
I am planning to built a stainless steel cabinet for my home. 
I am planning to use 18 Gauge 304 Grade SS. Dimension (Width X Depth X Height) of my cabinet
would be 30 inches X 24 inches X 34 inches. The cabinet top including appliances I am planning to keep on the top
 will weight around  20 -50 Kg. Now I am not sure whether I need a 
tubular framework (may be 1/2 inch) or  not. I would love a more
 generalization, that is - when one should consider a tubular 
framework instead of direct use of the sheet metal.
Sorry for my ignorance. Thanks
 

[Ted Ewert]

A load on top is going to bend your sheet metal without some sort of framework. I would even pit a few pieces across the top and down the sides to support the load. 

[swedefiddle]

Good Morning,

Basic Engineering. Strength is in using triangles for rigidity. Sheet metal by itself has no strength in a lot of directions. If you fasten it to some other things to create triangles, you gain rigidity. Think how an automobile body is put together, LOTS of Triangles, many directions, not by accident.

Keep It Stupid Simple, K.I.S.S. or Keep It Simple, Stupid. either way works to get the point across.

Enjoy the Journey

Neil

[dibakar]

Thanks a lot Neil.

[BIGGUNDOCTOR]

Take a look at commercially available steel cabinets and look at how they are made.

Beading sheet metal or adding other types of ribs adds rigidity.