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Discussion in '80-Series Tech' started by Arya Ebrahimi, Oct 25, 2005.
Title says it all.
Skip that and stick with the foam board
Trying to finalize my decision on material thicknesses for the bumper. I'd like to use a high grade steel, like slee does, but the shop I'm using says they will only form mild steel. I did some preliminary estimates and if I go w/ a 1/4" center and 3/16" wings the bumper alone(without a winch) will be right at 100#. If I go w/ 3/16 all around I'll save 10#, and if I go w/ 3/16 for the center and 1/8" for the wings I'll be down to 75#. Trying to decide if going to 3/16 or 1/8 on certain parts of the bumper will be detrimental to the strength.
IIRC the ARB is approximately 1/8" all around, with double thicknesses at the brackets and so on. I know how strong an ARB is, I'm just wondering if it's made of something other than mild steel.
You know I bet you could look all that info up on this new thing they've got.
Its called THE INTERNET!
50-11hundred pounds. Steel is the thick type. . . .
Hahaha, sorry dude, couldn't resist. I think they weigh 92 lbs, but I have no friggin' clue.
seemed heavy when I put it on by myself. But when I put slee's skid plate on the drivers side of the ARB the metal drilled really easy so I would guess it is mild steel....but only a poorly educated guess.
The ARB is close to 1/8". You have to remember that the ARB was made to hit animals and not so much rocks. The ARB gets its strength from the design and all the folds and bends in it, in addition to the upper tube that adds a tremendous amount of support for the wings. It was made to hit kangaroos at speed and take the impact, and probably sacrifice the bar and not the vehicle if the collision is big enough.
If you are building a rock bashing bumper of the design you have, then 1/8" for the wings are not enough. It will fold easily. Making strong wings is not that easy. We went with higher grade steel and the same thickness, since you get more strenght for close to the same amount of weight.
Christo, I appreciate the fact that you are willing to give me input even though I'm not buying your bumper. Believe me, if I could afford it, I would.
I'm "that guy" who's gonna have $300 invested in a bumper and a LOT of time. The guy people will reference when trying to figure out why your bumper is more $$ than $300. Don't worry, I will point them in the right direction.
I'd like your opinion as to whether or not you think 3/16" mild steel will be sufficient for the entire bumper given my design in the other thread. I don't go running head on into piles of rocks at full speed, but the occasional encounter with a rock is not unforseeable. I'm also concerned about whether the winch box will be sufficient at 3/16. It will "only" be housing a 9000# winch.
P.S. I will be adding an ARB-like hoop to mine in the future, as time allows to visit my friend w/ a bender.
Not much to add except that I can verify that the wings will fold and bend when using them to bash rocks.
I have a few bends and folds from boulders.
Odd thing is that it takes a whole lot of hammering with a very heavy BFH to bang it back almost to where it should be.
I can testify that the "air dam" on the bottom of the ARB POS bends on rocks easily too. :whoops:
The thickness and quality of the metal used is important, but the design of the internal structure, bracing and gussets will determine it's strength.
Gauging the low cost of the ARB I would bet that it is made of ASTM A36 or 1008/1010 Cold rolled steel. Both have about the same chemistry and strength. If you want to go high strength, I suggest ASTM A656 Grade 80 or 100. These materials are tough as it gets within reason. they are fairly priced and readily available. A656 in either grade in .125 thick for most purposes is stronger than 3/16" A36 or 1010. A656 is used on Semi truck suspensions, Loader booms, etc and other applications where high strength and light weight are critcial. It will require about 50% more tonnage to bend that A36 steel. If your fab guy has a 50-60 ton press brake he can most likely bend it in .125 thick.
I agree 100% with TOOLS R US on the internal structure, webs and bracing.
To calculate the weight of your new bumper take the surface area of the steel used x the thickness x .2833 to get the weight. EX, A 4' x 4' plate .125 thick is 48 x 48 x .125 x .2833= 81.59LBS
If need any help email me, I own a fab shop in ohio and can help get you the materials
I wouldn't be too concerned about saving 20-50 lbs on a bumper on a 5000 lb vehicle. Just my two cents. Especially if that bumper is meant to protect the sheet metal from rocks.
goes to show you that tech info on MUD never goes stale...
I want to add that the ARB isn't very heavy, but it's quite strong regarding aforementioned frontal impacts - the specs I've heard are an adult kangaroo at 55mph. It's a very high quality piece of metal, but probably not the best for bashing rocks with. It is quite easy to pick the entire bumper up via the top tube with two hands. We will go outside when it's light outside and measure ours with calipers.