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4" Sq Tube 1/4" wall strength question

nine4gmc

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I just picked up 12' of 4" sq tube 1/4" wall and want to build a heavy fab table with it. The top plate I have is 2" thick steel and according to calculations, it weighs about 1000 lbs roughly. Will the 4" tube be enough for legs that weight? I plan to use it on all four corners and tie them together with 2" sq tube 1/4" wall around the top and near the bottom where they will support a lower shelf.
 
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Kensgarage

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Sell the 2 inch thick, buy a sheet of 1/2 and pocket the leftover.The leftover will buy you kickass casters, paints, electrical boxes, expanded metal for the shelf....etc.etc
 

laser3kw

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what color is the tubing? :D

Sell the 2 inch thick, buy a sheet of 1/2 and pocket the leftover.The leftover will buy you kickass casters, paints, electrical boxes, expanded metal for the shelf....etc.etc

1/2" or 3/4" is p-l-e-n-t-y thick for the top plate. Leave plenty of over hang (6"~ 12") so you can easily clamp projects down near the edge. What is the size of the table?
 
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blazemaster83

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My 13ft tall gantry crane uses 3" tubing with a 3/16" wall, and is rated for 3 ton by the manufacturer.

4" tubing with a 1/4" wall will be plenty strong.

And don't sell your 2" plate. you will regret it if you do any heavy fab. If you need casters/paint,etc. just save up for it. I have owned a welding table with a 1/2" thickness and I would much prefer a 2" top. Now I have a 2" cast iron table from a horizontal boring machine and it is much much better.
 

zkling

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Most likely, but depends on the design. Answering vague structural design questions can be a real gamble.
 
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nine4gmc

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4" Sq Tube 1/4" wall strength question

I do have a 1/2" thick piece of plate a friend gave me but I have not picked it up yet, it's a bit smaller so I'll probably use 2" sq thick wall tube for legs on it and drill/tap a grid for clamping, it will be on casters and kept inside.

I think the 2" thick top table will be outside for heavy banging and welding out there . I don't do any serous fab work, just mess around some but I could not pass it up at about. $60 out my pocket. It's roughly 2'x5' or so.


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csp

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Sell the 2" and put the $60 bucks many times over back into your pocket, especially if you really don't have a need for it.
 
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nine4gmc

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It's not new so it's not really worth that much more with scrap prices down. I think I'll hold on to it for a while.


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mike13u

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Use the 2" top if you have it.

I have warped the overhanging edges (where you will likely clamp) on 1/2" steel table tops with heat from welding.
 

kkroger

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I would not weld to the plates...
I would probably do a flange with threads then drill and countersink the bolts to hold the top down. I would probably box in the leg frame a bit... My 5x5 plasma table is built from 11 ga 2x4 rec tube... The Water pan is 64x64x4" Holds 70 gallons that is 583# plus a 3/8 thick 4x5 steel plate is 889# The 11 Ga doesn't seem to care... I have loaded thicker plate on it too.
 
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nine4gmc

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I'm definitely flange bolting the top to the base structure on both tables. Only the frames will be welded together.


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Thumper68

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Plenty strong on mine I used 2 1/2 sq 3/16 wall.

For those who said sell no offense but you're nuts.
 
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nine4gmc

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Right on Thumper. :thumbup:

Creativecars, Thanks and I'll have at least one, possibly one on each side for versatility.


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PugetDude

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The folks advising you sell the 2" plate have probably never fabbed or welded on one.

The 4" 1/4" wall legs will make a really nice base for that plate.

Post pics of the build so all the "experts" can rip your design to shreds, critique your welds, tell you how you are doing it all wrong, and offer legal advice on how to sue the scrapyard that sold it to you.. :sad:
 
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nine4gmc

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I wasn't even going to mention that I'll be welding the 1/4" on a 110v mig but that's a whole nuther can o worms. :lol_hitti


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Strouty

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I wish I had a 2" top, I have to suffer with a 1 1/2" top, but my legs are 6 by 3/8" square. You are making me want to find a thicker piece of steel.
 

soj

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Nine, that's impossible. You can't weld anything thicker than a gum wrapper with 110V. Please reconsider before you get someone killed.

I am calling BS on that. I can weld 32GA all day long with a 110V welder. Just have to pre-heat it with a torch... and take your time. MacGyver taught me how. :rocker:
 

MoonRise

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Your 4" square 1/4" wall steel tube legs will be plenty 'strong'.

Four 4" x 1/4" wall legs, ignoring buckling and bending and fatigue, can hold up approximately 375,000 lbs. :D Your 1000 lb plate top is nothing. :lol:

(4^2 - 3.5^2) x 25,000 psi yield strength x 4 legs = 375,000 lb total load capacity to yield

Oh, and some 2" thick plate 2' x 5' should weight about 'only' 815 lbs. 24" x 60" x 2" x 0.283 lb/in3 = 815 lbs. Even lighter than you originally thought! :D
 

csp

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For those who said sell no offense but you're nuts.

Maybe you missed the part that the OP is just going to let it sit outside for occasional use. I'm fairly certain that those who say to keep it wouldn't let it sit outside.:dunno:
 

Thumper68

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I saw that part I also know lots of people who do their heavy welding outside.

Treat the top with a nice heavy coat of used oil once a week and it will not hurt it at all.

If you are ever in a "real" fab shop you will see that the tables they use are Thick

To properly clamp things so they don't move under stress you need a ridged top.

Funny no one told me to sell my 2" top when I was building mine and I used whimpy 2 1/2-3/16 legs.
 

jimgood

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I wasn't even going to mention that I'll be welding the 1/4" on a 110v mig but that's a whole nuther can o worms. :lol_hitti


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:lol: I was just going to suggest you use a 110v welder so as to really bunch some undies!

Thanks for that!

Sounds like a good score. I'm envious.
 

dr_clyde

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Both my big tables have had 4" 1/4" wall legs. No problems to report yet. If I could have swung it I would've gone with a 2" top myself.
 
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nine4gmc

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Your 4" square 1/4" wall steel tube legs will be plenty 'strong'.

Four 4" x 1/4" wall legs, ignoring buckling and bending and fatigue, can hold up approximately 375,000 lbs. :D Your 1000 lb plate top is nothing. :lol:

(4^2 - 3.5^2) x 25,000 psi yield strength x 4 legs = 375,000 lb total load capacity to yield

Oh, and some 2" thick plate 2' x 5' should weight about 'only' 815 lbs. 24" x 60" x 2" x 0.283 lb/in3 = 815 lbs. Even lighter than you originally thought! :D

The dimensions I mentioned were off, it's actually 27" x 66" x 2" and weighs roughly 1010.7504 minus a few drill holes. :thumbup:

Nine,
I just posted up a welding/fab table that I put together over the summer. It is not nearly as heavy or quite as large, but still gets the job done on a smaller scale.
My $.37 per pound table...
http://www.garagejournal.com/forum/showthread.php?p=5225288#post5225288

Just opened it to read when I get back home. Thanks for the link!
 

csp

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If you are ever in a "real" fab shop you will see that the tables they use are Thick

To properly clamp things so they don't move under stress you need a ridged top.

Funny no one told me to sell my 2" top when I was building mine and I used whimpy 2 1/2-3/16 legs.

Funny you assume that I've never been in a "real" fab shop or maybe even have my own fab table (I have an Acorn BTW as well as smaller general use tables).

The point you're missing is relevance and application. The OP isn't doing "real" fab work by his own admission. Just because he has a 2" thick slab doesn't make it make sense. I'd rather see someone who actually has a need for one make use of it instead of letting mother nature wreak havoc on it.:willy_nil
 
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nine4gmc

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It may go inside, it's not over with yet. I'm going to get started drawing it up and may get started this weekend.


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