How to size steel for workbench frame

[koenbro]

I am planning to build a simple wood-top, steel-frame workbench. It will be used for regular DIY, home garage work (no more than 500 lbs total load). The bench will have a wood top that is a 74" x 25 5/8" x 1 1/8" (IKEA countertop).

Am thinking adjustable-height legs with 1.5" square tubing lower halves inserted into 2" uppers. At the ends, the legs will be connected with square tubes in an "H" pattern. These end pieces will then be connected along the length of the table with cross members made from L iron. Finally I will add 2" receiver hitches at the ends.

How can I decide the size of steel for the legs (square tube) and frame (L steel) of the workbench? Specifically, what thickness of material should I consider?

I know some people think along "more is better" but I don't plan to build a heavy monster of overkill that will be impossible to move. I am a completely newbie at this so anything to start my planning process will be greatly appreciated.

 

[Nor'Easter]

If you want something basic then 1/8" wall tubing is fine.

If you plan on dropping blocks and transmissions on it I'd go heavier.

One thing to consider is that with the thinner wall, the pins you use to adjust the heigh could ovallize the holes. It would take a long time, but could still happen. Using a larger pin will help slow that process down.

 

[Richard D]

I'd use whatever you have left over from the legs, 1-1/2" or 2" will be plenty.

 

[Richard D]

Instead of pins and sliding tubes, I used big stud bolts and nuts so mine is easy to level on an uneven surface, or even raise or lower it several inches, though I haven't touched them since I built the table and leveled it a couple years ago. I doubt you will ever want to raise or lower the table a drastic amount; I have two big tables and have never felt the need.

 

[Nor'Easter]

Instead of pins and sliding tubes, I used big stud bolts and nuts so mine is easy to level on an uneven surface, or even raise or lower it several inches, though I haven't touched them since I built the table and leveled it a couple years ago. I doubt you will ever want to raise or lower the table a drastic amount; I have two big tables and have never felt the need.

Or do both.

 

[koenbro]

So got the steel today -- went with 1.75" uppers and 1.5" lower leg parts. Also picked up a StrongHand FixturePoint welding table with a modular fixturing kit for square tube. Once done with the workbench, will make a welding table, with casters and self-leveling feet, but using this top.

2015-11-21 16.18.28 by L V, on Flickr

 

[sberry]

90% of the features you will never use, once the height gets set it will stay. 1/8 is plenty, a 14ga leg half that is good for 1000's of #

 

[zkling]

Google strengh of materials, or, get a copy of machinery's hand book and start reading the section on strength of materials. Or go and get a undergrad degree in mechanical engineering. The latter is very expensive in time, money and patience.

More is not always better and just shows a lack of knowledge from the designer. It just needs to be stiff enough to accomplish the job at hand SATISFACTORILY.

 

[koenbro]

Due to availability limitations I went with 14ga for both leg bottoms and top (1.5" and 1.75" respectively). Will wait for the arrival of my saw and hopefully will have pictures to post in one week.

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