Topic: HREW vs. DOM options

[Burl]

Just wondering if anyone has encountered square or rectangle tube that is DOM.  I'm pretty sure its mostly all HREW.  The real issue is whether anyone has used square  or rectangle tube as media for an interior cage/cargo retaining system.  On my FJ60 there are some bends that I would like to see but don't think are possible for the dash area.  With angled cuts and fish plates I believe these angles could be achieved.  Otherwise using round tube would be excessively in the way and not a good use of the available space.  Ya I know nice one piece bends in tube with limited connections are by far the stronger way to go, but does the square or rectangle pose more of a threat than not having anything at all?  Let the comments roll!

[junya92toy]

Square tubing is stronger then round.

[Burl [OP]]

I was thinking since my bumpers on the 60 are rectangle tube an interior rectangle or square tube cage/cargo kit would look nice and clean.  FJ60's are kinda squarish and boxy anyways.

[junya92toy]

Well this has been talked about before, but wheather its dom or hrew, design and quality welding is what really matters.

[pumkin toy]

Square tubing is stronger then round.

how do you figure?

[junya92toy]

How do I figure? Its been proven.

[94MtnYote]

How do I figure? Its been proven.

Where, when and how?

[junya92toy]

Its 30% more stronger, because its got about that much more in steel, bigger cross section as well

2 inch round with a .125 wall deflects .79 inches.
The bending stress is 55382 psi
2 inch square with .125 wall deflects .46 inches
The bending stress is 32623 psi

[pumkin toy]

explain to me how the bending stress is measured.  if i am reading that right, it only takes 32623 psi to bend square tube and it takes 55382 psi to bend round tube, which would mean that it takes less psi to bend square tube of the same wall thickness as round tube.

[4RunnerChevy]

explain to me how the bending stress is measured.  if i am reading that right, it only takes 32623 psi to bend square tube and it takes 55382 psi to bend round tube, which would mean that it takes less psi to bend square tube of the same wall thickness as round tube.

I am with you, just waiting for j to do his google thing.

[junya92toy]

Why dont you search for yourself, square is stronger.
I forgot to add  those numbers were with a 3 feet long piece and a 500 pound load placed on them.

[pumkin toy]

Why dont you search for yourself, square is stronger.

dont be backing out now....... anytime someone starts a thread about this stuff, you jump in right away with your info.  so i figured that since you know so much about this subject, that you could explain it for us

[junya92toy]

I did, its got a bigger cross section, due to 30% more steel compared to round, if you say 1.5inch x.125 wall.  And I showed square deflects less under the same load.

[spoolnaround]

Info that I have come across,

source: http://www.offroadfabnet.com/forums/showthread.php?t=5499&highlight=square+round

A round tube will be structuraly the same around the entire circumfrence. So if you hit a round tube at any point it's going to be the same (relitively) strength the whole way around. With square tube you basicly have 4 really strong points that lose some of their strength as you work twords the center of the tube. So in the eventuallity (or probability) of a roll over if Murphy (Law) is anywhere nearby the contact is going to take place at the weakest point in your design or material.

One of the reasons why people don't build chassis with square tube is the strength to weight ratio compared to round tube. A 1.75" round tube is going to be significantly lighter and stronger then a 1.75" square tube. The 1.75" round will almost slide into a 1.75" square. The corners add a lot of weight and little for strength.

The other issue I foresee is bending the square tubing. Even a good quality draw style bender is going to have some warpage or collapsing at the inside of the bend point. This then makes your bend the weakest point of the cage and prone to collapse. And if your cutting and welding to make bends your weld or the material around your weld will then become the weak point. And for the record I am not picking on your welds at all. For all I know your the best welder in the world it's just at that point the metal around your weld becomes the issue!

One last question/comment... Do they even make DOM square tubing? All the square tubing I've used or seen has been a CREW/HREW style tubing... Big ugly welds down the inside of the tube. Not exactly ideal for a cage expecially on a heavy rig like an International!

With that being said I have seen entire buggies made out of square tubing... But at the same time I've seen buggies made out of SCH40, SCH80, and others out of HREW. At that point it's not a matter of when the cage fails but how bad it will be when it does!

Paul G.

[Sparkplug]

Info that I have come across,

source: http://www.offroadfabnet.com/forums/showthread.php?t=5499&highlight=square+round

A round tube will be structuraly the same around the entire circumfrence. So if you hit a round tube at any point it's going to be the same (relitively) strength the whole way around. With square tube you basicly have 4 really strong points that lose some of their strength as you work twords the center of the tube. So in the eventuallity (or probability) of a roll over if Murphy (Law) is anywhere nearby the contact is going to take place at the weakest point in your design or material.

One of the reasons why people don't build chassis with square tube is the strength to weight ratio compared to round tube. A 1.75" round tube is going to be significantly lighter and stronger then a 1.75" square tube. The 1.75" round will almost slide into a 1.75" square. The corners add a lot of weight and little for strength.

The other issue I foresee is bending the square tubing. Even a good quality draw style bender is going to have some warpage or collapsing at the inside of the bend point. This then makes your bend the weakest point of the cage and prone to collapse. And if your cutting and welding to make bends your weld or the material around your weld will then become the weak point. And for the record I am not picking on your welds at all. For all I know your the best welder in the world it's just at that point the metal around your weld becomes the issue!

One last question/comment... Do they even make DOM square tubing? All the square tubing I've used or seen has been a CREW/HREW style tubing... Big ugly welds down the inside of the tube. Not exactly ideal for a cage expecially on a heavy rig like an International!

With that being said I have seen entire buggies made out of square tubing... But at the same time I've seen buggies made out of SCH40, SCH80, and others out of HREW. At that point it's not a matter of when the cage fails but how bad it will be when it does!

Paul G.

Alot of that doesnt make sense to me, in the real world. How is it I can smack a piece of  round tube on something, and bend or dent it, whereas same thickness sq tube, will just bounce off and hurt my hand?

Ive also read sq is stronger than round, more surface area to spread the load on.

[Nimyad]

look at yotamans cage, yes it's stainless but it's rectangular tube everywhere. and no they don't make square DOM. Now IMO i think both square/ rectangular and round would be strong enough for your application, it just comes down to which you think will look better and which you want to work with

[Burl [OP]]

I tried to search for "yotaman" to find pics, could you copy paste the page link.

[Nimyad]

oh sorry it's yodaman. his site is http://www.yodaman.net/ he has some pics of his truck on there, 2nd gen

[junya92toy]

Alot of that doesnt make sense to me, in the real world. How is it I can smack a piece of  round tube on something, and bend or dent it, whereas same thickness sq tube, will just bounce off and hurt my hand?

Ive also read sq is stronger than round, more surface area to spread the load on.

You know why the square just bounces and not bends? You are trying to bend 2 pieces of flat bar on the sides basicaly. Think of stand on a pop can, you put a dent in the side and the whole thing smashes down. Now do that with square and the load is at the corners to start with, so no smash,

[Burl [OP]]

I'm fine with using square and rectangle tube on the outside as bumpers and such.  Yodaman's pics of the square tube exo look good but i'm looking more for an interior cage.  The IH8MUD forums generally lead to round being more popular, the square and rectangle applications seem to be case specific and have worked so far but this kinda leads into the realm of "normalization of error" meaning it works and hasn't had problems yet but there is potential for failure more so than round DOM.  I'm thinking I may have to sacrifice some space and just go round.  Thanks for the opinions and info.  Keep this thread going if you wish.

Thanks

[Slolyfe]

I tried to search for "yotaman" to find pics, could you copy paste the page link.

[86rustbucket]

well since everyone is on the subject. Does anbody actually know where to find round DOM in central california?

ive tried valley iron and got looked at like i was stupid, called a few other places around town and found nothing.

i know there's a couple places online where you can order it and i know you can get it in sacramento, but what about fresno?

[Twisted]

well since everyone is on the subject. Does anbody actually know where to find round DOM in central california?

ive tried valley iron and got looked at like i was stupid, called a few other places around town and found nothing.

i know there's a couple places online where you can order it and i know you can get it in sacramento, but what about fresno?

You can get it from valley iron, but they have a minimum order quantity. Dont quote me but I believe its 100'.

[Burl [OP]]

I have heard that it can be purchased near Visailia somewhere.  That's where I'll be getting it.  My father in law builds tube chassis for sprint cars that's where he gets his stuff.

[junya92toy]

Youre wasting your money

[steveco.]

you can get DOM from Tube Service Co.  www.tubeservice.com 

[Rocksnail]

Rustbucket you can get dom at valley iron. But i beleave you have to order so much at a time. Thats why i just went with hrew when i did my cage.

[pumkin toy]

Youre wasting your money

who is wasting there money?

[spoolnaround]

Youre wasting your money

?? wow, from what I have read here in just this thread I will ignore any and all tech you spew.

[junya92toy]

O ya why is that? DOM is way over kill, for a offroad truck. Its far cheaper to just use ERW