cage?

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I am building a rollcage into my pig and I am going to go with angled corners since I dont have a bender. I know that I need to gusset it for extra strength that is lost with the angled connections and welding. My question is which works better using tube steel or sheet steel because I have seen both. I would think that tube would be stronger but the sheet steel can get all the way into the angle.
 
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I'm no mechanical engineer, but my thought is that if the force trying to change the angle between the two tubes is in the plane of the gusset, the sheet steel wins (as long as it's thick enough not to itself deform); while if there are twisting forces, the tube gusset wins, but not by much... and OTOH that's not what a gusset is for. So, I'd go w/ sheet.
 

Mace

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Think of it this way.. Which one has a greater surface are per tube to add support???


(the tube btw)
 
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I was imagining thick enough sheet gusset that the main tubes would deform (hinge) first; but I guess that's not apples-to-apples, though...

"Reaching into the angle" doesn't add as much strength (unless the main tube weld is questionable) as does material at a distance from the angle (i.e., more meat further away)...

So for the same triangle size, the tube gusset _does_ win if the gusset tube wall thickness is roughly the same as the sheet thickness. It really depends on the dimensions, but I guess I have to flip-flop... OK, for the general case of equal thickness: tube it is.
 
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Do both...put in a 1/2 or 3/4 inch steel plate then do the tube and weld it all together. Basically make a triangle and fill it in with the sheet metal. Then it is for sure to hold up.
 
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The closest place around here with a real bender is about 45 min away and I am not going to pay them a bunch and bring my rig all the way out there. I have free tube and I'm not going to waste it. Besides I am confident that I can build anything I just might not have the best equipment for it in this case ie a bender. I was thinking about doing the sheet and tube like Chuck (cruisintiger) said I just wanted to see what other people have done.
 
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Another way to do it is to do two 45deg joins instead of a single 90deg. This works out nearly as strong as a smooth bend. Plus it looks a lot better than a simple 90deg join.

Mandrel.gif

Also, a welded join of pipe will be stronger than the pipe given that it is a full penetration weld with the same root thickness as the pipe wall thickness.
Mandrel.gif
 
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At Oregon State University, they participate in this mini Baja race, the cars are built there, in order to qualify your car you have to prove that it meets strength standards, because there isn't a good way to model joints in a roll cage that are formed, they make there cages with cut and coped joints, as long as you tie your cage together properly the joints can be made most anyway, it's the diagonal bracing that ads 90% of the strength to a cage. it's only as strong as the memeber loaded in the most inappropriate way. a cut and coped cage may not look as pretty as a formed one, but it can be equally as strong as any other.

http://groups.engr.oregonstate.edu/SAE/Baja/
 

Mace

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Milo said:
Another way to do it is to do two 45deg joins instead of a single 90deg. This works out nearly as strong as a smooth bend. Plus it looks a lot better than a simple 90deg join.

View attachment 46181

Also, a welded join of pipe will be stronger than the pipe given that it is a full penetration weld with the same root thickness as the pipe wall thickness.

Untill you take into account the heat put into the welds weakening the material around the weld..
 
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i will always hold to a properly executed mitered and gusseted cage as being stronger than a comparable bent one. mind you i am in no way saying a traditional cage is inferior, on the contrary. weight and looks is usually the driving force, a cut and gusset cage will be and should be a fair amount heavier. i see no problem with your intentions clemson as long as its done well. good luck.

that said a solid gusset will yeild a stonger joint, especially if you use square tube for the gusset incorporating a much larger area of tube than just the centerline. oooh that doesnt sound right, lemme elaborate. make the gusset as you would with a flat plate, but use a large enough chunk of square or rectangle tube to essentially end up with TWO flats joined by the 3rd edge of the tube, make sense?
 
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Mace said:
Untill you take into account the heat put into the welds weakening the material around the weld..
Yes the heat affected zone will be the weakest link but the action of bending stress hardens and weakens the bent joint too. It is six of one and half a dozen of the other. In both cases heat treatment after fabrication relieves most of the negative effects.
 
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Not sure I'm following you there rhino. I haven't gusseted anythign yet though and probably wont for a little while longer. However what I have done can be seen in the 55 section.
 
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If you spray cold water on the welded section right of way, it will harden it, I just use a spray bottle.
If you don`t beleave me, take some metal, weld on it, or just heat it up, then cool it with water, then try to cut it with a portaband saw, or drill it, you will dull the blade instantly, and it doesn`t even start to cut the metal.
Don`t even try to drill it, if you like to keep your drill bits sharp.
 
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I don't know all about the cut and miter thing. To me it seams that bent tube will always be stronger. One piece of tube going from one side to the other in a hoop with no cuts or welds seames to be a lot stronger than a weld in 90's. Now it all boils down to what you will use the truck for and the how extreme you are taking the rig. It also depends on what you think your life is worth. To me the most important part of an offroad truck is the cage. not the winch, tires, or axles. I have seen built trucks that spend all the money on the drivetrain, and winch. Then have a stock cage or a porly built one. They roll then it is all real apparent to them where the money should have been spent.

Notice the Dana 60 and 14 bolt, Hydro steering, tires and wheels, and other goodies. He was lucky and he was unhurt.



Now I am not saying this because I build cages. I say this so people can understand that without a well built cage from any shop all the winches, tires, axle, and other upgrades the only one that will save you is the cage.... 45min drive and $1500 -$2000 is worth it to me. You can buy a bender with the die you need for about $500 and when your done sell it to someone else that needs to build one. I also would do some research on the spraying water thing.

Now this is not ment to upset anybody by any means. I just want to bring up another point of view so I won't see someone else in the same situation as My friend Kieth.
 
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Scottb said:
If you spray cold water on the welded section right of way, it will harden it, I just use a spray bottle.
If you don`t beleave me, take some metal, weld on it, or just heat it up, then cool it with water, then try to cut it with a portaband saw, or drill it, you will dull the blade instantly, and it doesn`t even start to cut the metal.
Don`t even try to drill it, if you like to keep your drill bits sharp.

Maybe so, maybe not, but consider hardness and toughness are not the same thing.
Glass is very hard...

Another example for those that have tig welded, tungsten is very very hard, and how much effort does it take to break off a contaminated end ? Kahsnap!
 
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Drunk Monkey where / who do you build cages for. I am cool with your opinion its the whole reason I asked over here to see what people think.

I am confident in the angled cage though. You and everyone else can check out my progress in the 55 section and see the gussetting and all. I believe it will be very stout when I am done. No its not tied to the frame yet and thats already been brought up in the thread but it will be tied in when all is said and done.
 
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Quick quenching is the way to brittle parts.

You don't want your cage hard to drill, you want it tough and resilient.

"Grasshopper, The tree that bends stands again, the tree which will not bend breaks before the wind. To live, bend"........over. :D
 
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That is why I would use a spray bottle, and not dunk a steel part in a tank, it only tempers most of the outside not all the way through.
Just like harden axles are not hardened all the way through, only part of the way so they are stronger, but not brittle all the way through.
I haven`t seen a well built cage ever break at the welds, even a poor design cage break at the welds, if the welding is done right.
If someone has pics of a broken cage at the welds, please post them up for reference, that would be great.
Here`s some great info http://www.matsci.ucdavis.edu/MatSciLT/Other/Files/HT-Steel.pdf
 
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Mace

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Scottb said:
That is why I would use a spray bottle, and not dunk a steel part in a tank, it only tempers most of the outside not all the way through.
Just like harden axles are not hardened all the way through, only part of the way so they are stronger, but not brittle all the way through.
I haven`t seen a well built cage ever break at the welds, even a poor design cage break at the welds, if the welding is done right.
If someone has pics of a broken cage at the welds, please post them up for reference, that would be great.
Here`s some great info http://www.matsci.ucdavis.edu/MatSciLT/Other/Files/HT-Steel.pdf
Bull,

No offense but that is the WORST idea. In a roll you will be much more likely for the surrounding area around the weld to fail instead of bend..

I really cannot believe that you would reccomend this..

There is a HUGE difference between case hardening and your theoretical case embrittlement.
 

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