Alright, here's the question. Just sittin at work a little short of work, and got to thinkin about building a tube frame buggy, or truck, or whatever. I got a small quantity or 1 7/8" 1/8 wall welded seam tubing at home and was using it to add on to my roll cage. Easy to weld with, fairly easy to bend, and I KNOW it's strong, because I rolled my play truck and it held up, needing minor repairs. Now, in my quest of 'building a tube frame buggy', it can be difficult to get all the bends to match up *just right* without a precise tubing bender, be it a mandrel bender or a standard die bender. Box tubing, say, 2x2, or 1 3/4x 1 3/4, 1/8 wall, would be a lot easier to cut and weld for fitment purposes, as well as welding brackets etc on to. My only concern is strength. I thought I remembered that, given the same proportions, round is stronger than box, whether it's welded seam or chrome moly tubing. It makes sense that round would take bending better than box; it seems that box would bend only so far, then basically shear under the forces, where round would continue to bend (to a degree). Of course, the weaker of the two can ALWAYS be gusseted for strength, or the quality of steel can be upgraded, but as a generality, given the same dimensions, what's stronger, welded seam box or welded seam round?

 

Its not even a competition. The round stock is stronger.

 

I had a rear tube bumper built out of 2" x 1/8 welded seam wall and it bent pretty easy just getting my bumper against a tree and not knowing it and hitting the gas. No impact really. I did not even know I mangled it until I got out to retrive my cable. I do not think I would trust my life to it or build a frame of it. I would make cross members out of it though to box a frame if I did not want to waste it. You can bend 1 7/8 x 1/8 with a 2.5 ton floor jack.

1 7/8 x 1/8 tube is way too weak, imo, for anything other then a VW buggy, though it might be stronger then 1.5 square tube (have not tested that), it will not be stronger then 2" channel because the 2" channel has a big radius in the two corners and no welds.

For anything you will hammer off-road, for a frame I would think the min. would be 3/16 x 4" C-channel, if I did not want the frame to droop or rip, I would go with 6" for a V-8 and big axles. Plus, it is much easier to attach body mounts, engine mounts, spring hangers, etc. to C-channel then to tubing and the tubing is likely to rip when stressed at/near welded points vs. twist like C-channel where it is riveted/bolted together.

 

you prolly have never seen a hardcore crawler have a tube out frame usinf square...that should twll ya something! stick to round although square will still be plenty strong!

-cutts-

 

Upgrade to 1/4, it may be harder to work with but the extra strenght will be more than worth.

 

most benders will not allow easy bending of 1/4" materials. my buddy just picked up a hydro bender and they said not to even try bending 1/4 wall.

Tube buggies made out of .120 wall DOM are super strong. they are taking hard rolls all the time and thier cages / frames take the beatings just fine.

 

I thought that those buggies would've used something a little thicker than .12 wall stuff, One also would've thought that a hydraulic bender would be able to bend 1/4" tubing. Ya learn something new everyday.

 

/.256 is really aloot. But I think we need more for our fullsizeds.

 

you start using .250 wall pipe you will need a second cage just to hold up the weight of the first cage, if I remember correctly nascar only requires .110 wall, and when they roll it's at 180mph, and from what I have read in the past even the monster trucks only use .140, I personally am running .125, and think anything over .140 wall pipe is just adding even more weight to an already heavy truck with no benifit.
but for frame rails I think I would run with 2x4 .250 wall rectanglar box tubing, using round tube for the frame you really need atleast 2 rails with gussets, and supports to keep it from twisting on round tube will not make a good frame rail. even though thats what they use on the buggies take a close look they use 2, and sometimes 3 tubes on each side set about 1in apart, but have seen it done with 1 piece of rectanglar tube.

 

I agree that round is stronger, but think about an early Bronco or scout- rectangular boxed frames- very light and plenty strong. I'm a scrawny ******* but when I get an early Bronco stripped down to nothing but a bare frame, I can pick up the entire frame myself and carry it where I need it. Only problem is that rust is as unkind to a thin frame as it is to sheetmetal.

 

There is also a big difference between DOM and "wall welded seam tubing" and what they use in NASCAR. I dare to say that a guy welding a NASCAR vehicle has better experience, tools, and materials then any of us could hope to have in our vehicles.

BTW: I have bent 3" x 1/4 steel tubing in my bender from northerntools.com, so it is not impossible. You just can not do a 90 degree bend.

 

I know my buddy who bought the bender did not skimp on tools. He already has a Miller 251, a Hobart plasma that can cut 1/2 plate. So I am pretty sure these are just as good of tools that Nascar would use.


What kind of bender did you get from Northern tools?

 

I think you're talking a few different things here. I know that a DOM bend is better than a die bender; there's no fluctuation in diameter with a DOM bender, as opposed to a die bender. As to the welded seam tubing, is chromemoly also welded seam? I figured it would be; how else would you get a piece of steel to be a tube unless is was cast that way? Or is there really a DOM steel tubing that indeed has no seam? I was just under the impression that, judging by the price, the stuff I have is mild steel as opposed to chromemoly steel. I've got some small diameter chromemoly tubing that has a seam in it. Or at least I was TOLD it's chromemoly tube...

 

Ahem. Translation: .250 wall is crazy thick/heavy. But I would feel funny about running the standard .120 on a full size rig, also. I'm sure the DOM would handle it, but...

 

I agree that .250 is a bit more beef than necessary. That's why they also make .187, I assume.