Welding Tips and Tricks

I'd like to learn about the engineering behind metal structures so I can plan out projects with the correct materials and welds up front.

For example, I want to build a table that is has a wood top of about 200 lbs, 4x8 feet in dimensions and suspended by a single cylindrical pedestal at its center. I was going to have the pedestal connect to a 2x4 plate of some kind (5/8 or 1/4) then recess the wooden top so this plate fit flush with it. I wasn't sure if I could get away without gussets or what size pipe would be big enough to handle this. Shallow 2" gussets made from channel would probably work, but without building it I don't know what kind of stresses this base structure can handle. Or how much deflection I could expect as a load cantilevers on the furthest part of the table.

So yeah, I'd really like to learn how I could calculate this stuff so I can get the right materials for the job. Thanks!

You can approximate simple structures using formulas like those found in the Machinery's Handbook. You can calculate both stress and deflection of the base structures. You can also look for PDF's and legally download them as they are sometimes made available by universities and the students in engineering programs. Better to stand on the shoulders of giants than to try to reach the clouds by jumping up from the ground. If that is not enough, then there is a mechanical engineering degree waiting for you.

Just a guess but a 4 ft x 8 ft top will need a 6 inch or 8 inch pedestal post. But probably only a 3/8 plate 18 inches by 36inches.

Edit
You will need a more substantial base plate or legs to spread out the weight and stabilize it. Like 2ft by 5.5ft.

Poland308 wrote:Just a guess but a 4 ft x 8 ft top will need a 6 inch or 8 inch pedestal post. But probably only a 3/8 plate 18 inches by 36inches.

Edit
You will need a more substantial base plate or legs to spread out the weight and stabilize it. Like 2ft by 5.5ft.

Ah, I was planning on bolting it to a plate that would bolt to the rafters or have a pour a footer and have the table go through the floor and bolt right to the footer. Or maybe screw onto a plate which was bolted down to the footer. One of these two. I did want the ability to adjust it in the future if say the house settled a little bit. Which it kind of does.