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Discussion Starter · #1 ·
Hello All,

I joined the forum as I will be starting an interesting project soon and looking to get some insight from the custom fabricators on here. My dad has a rhino 660 that has spent the past few years on the beach in mexico where the frame has rusted out. My plan right now is to rebuild the frame with 6061 rectangle and round aluminum tubing. And before I get the whole "its not as strong as steel" thing, I'm not looking to compare steel vs aluminum. The frame will be rebuilt accordingly. Also, the rhino isnt being ridden hard, just used for running up and down the beach. Im really just looking to see if anyone else has tried such a project with a Rhino or your thoughts.

Thanks!
 

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This should spark a lively discussion. Here is my $.02.

7075 is nice and strong stuff, but it cannot be welded. 6061-t6 is strong stuff and it can be welded. To bend 6061-t6, you will have to anneal it. I forgot the temps (seems like about 750ish). I used a heat crayon and rosebud to get the aluminum hot/soft enough to bend it, without fracturing. However, once it is annealed, it is now dead soft and has lost its strength.

You can tig and mig 6061-t6 and, it welds very nicely, with patience and practice. But, the welding temps will anneal the metal. So it is no longer at the t6 temper. The bad news is that the welded joints will be soft. This is not a good thing! And aluminum does a great job of transferring heat, very quickly. So, the softness will probably extend beyond the welded joints.

I have never done this, but I have been told that a welded aluminum frame can be heat treated back up to t6. This sounds like big $$$$$ and I am not sure how they control warpage.

The question that I have is how much weight is saved by using aluminum (as compared to steel) to have a finished product with the strength of steel? I have no idea. Perhaps someone smarter than me can chime in.

Lastly, years ago, a fellow gearhead paid big money to have his sand rail "reframed" out of aluminum, to go faster. I told him that he was as ffff'g dumb as a box of rocks and that he was going to kill himself and/or his passenger. Two months later, he made a huge jump and flipped his rail. The aluminum frame collapsed (like a chewing gum wrapper) and his head was jammed into the sand. He had a compression fracture of his neck. The only thing that saved his dumb a$$ was the EMT crew who knew how to immobilize his head, prior to extracting him from the rail, so they would not sever his spinal column. Had his spinal column been severed at the neck, he would have been a quad (and not like the one with wheels).

He had to wear a "halo" for about a year. A halo is medical device that keeps the head from moving, while the neck bones mend back together. The doctors actually drilled and tapped his skull and then attach the halo to his skull with bolts. Grosses chit I have saw. The skin around the bolts was always reddish and infected. Constant headaches. No haircuts, hair washing and someone else had to wipe his butt because he could not twist his body. He slept sitting up because he could not lay down on the halo.

So, why do you want to build the frame out of aluminum? LOL.
 

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This should spark a lively discussion. Here is my $.02.

7075 is nice and strong stuff, but it cannot be welded. 6061-t6 is strong stuff and it can be welded. To bend 6061-t6, you will have to anneal it. I forgot the temps (seems like about 750ish). I used a heat crayon and rosebud to get the aluminum hot/soft enough to bend it, without fracturing. However, once it is annealed, it is now dead soft and has lost its strength.

You can tig and mig 6061-t6 and, it welds very nicely, with patience and practice. But, the welding temps will anneal the metal. So it is no longer at the t6 temper. The bad news is that the welded joints will be soft. This is not a good thing! And aluminum does a great job of transferring heat, very quickly. So, the softness will probably extend beyond the welded joints.

I have never done this, but I have been told that a welded aluminum frame can be heat treated back up to t6. This sounds like big $$$$$ and I am not sure how they control warpage.

The question that I have is how much weight is saved by using aluminum (as compared to steel) to have a finished product with the strength of steel? I have no idea. Perhaps someone smarter than me can chime in.

Lastly, years ago, a fellow gearhead paid big money to have his sand rail "reframed" out of aluminum, to go faster. I told him that he was as ffff'g dumb as a box of rocks and that he was going to kill himself and/or his passenger. Two months later, he made a huge jump and flipped his rail. The aluminum frame collapsed (like a chewing gum wrapper) and his head was jammed into the sand. He had a compression fracture of his neck. The only thing that saved his dumb a$$ was the EMT crew who knew how to immobilize his head, prior to extracting him from the rail, so they would not sever his spinal column. Had his spinal column been severed at the neck, he would have been a quad (and not like the one with wheels).

He had to wear a "halo" for about a year. A halo is medical device that keeps the head from moving, while the neck bones mend back together. The doctors actually drilled and tapped his skull and then attach the halo to his skull with bolts. Grosses chit I have saw. The skin around the bolts was always reddish and infected. Constant headaches. No haircuts, hair washing and someone else had to wipe his butt because he could not twist his body. He slept sitting up because he could not lay down on the halo.

So, why do you want to build the frame out of aluminum? LOL.
Aluminum is way different than steel in regards to the heat treatment.

You heat steel to a high temperature and quench it it becomes very hard, and quite brittle! You have to heat it to a moderate temperature and slowly cool it to 'temper' it. This gets rid of the brittleness at the expense of a small part of the hardness.

You heat and quench aluminum it becomes very soft. You leave a proper alloy of aluminum (such as "6061") set for years and years it will slowly gain it's full hardness. So what you do is raise the temperature to a moderate value for a long time in an oven and then let it naturally cool down. This is called "artificial aging", which is what the -T6 designation after the 6061 stands for. This is very important in the design of a welded structure. If the welds are in non-stressed area, you can get away without re-doing the artificial aging heat treatment. But, if they are in the highly stressed area it folds up when you over-stress it. You do want to know what you are doing when you build a crash cage.

When designed right, and done right, an aluminum structure can be almost 3 times stronger for the same weight, or nearly as strong with 1/3 of the weight. If not done right, it is the equivalent of an empty beer can.
 

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Discussion Starter · #4 ·
The main reason I am choosing aluminum is mostly for the corrosion factor of the salt water humid environment it resides in. Luckily there are a few heat treat facilities here in Phoenix that will be able to assist with heat treating of the frame after construction. It should turn out to be an interesting project to be honest. But all feedback is welcome.
 

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If you're not going to be beating it up, then your probably not going or planning to go crazy fast, then weight is not an issue. Use stainless... Super strong and corrosion resistant. Just a thought. I know it's really heavy, but you'll get the corrosion resistance and safety!
 

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The main reason I am choosing aluminum is mostly for the corrosion factor of the salt water humid environment it resides in. Luckily there are a few heat treat facilities here in Phoenix that will be able to assist with heat treating of the frame after construction. It should turn out to be an interesting project to be honest. But all feedback is welcome.
Good enough. You often see lots of triangular gusset plates at the frame joints in welded aluminum construction. That helps to move the peak stress areas away from the welded around joints where the tubes meet and move it out to the area where the gussets taper away, which will have comparatively very little in the way of heat affected zones.

For the salt water corrosion resistance it will be good. But.... Beware! The fasteners that you put in, as there will be galvanic corrosion issues that can eat up the bolts and/or the aluminum. Read up and study the alternatives carefully.
 

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Wow is this a big can of worms! Aluminum will work if you just pass on the heat treating ( a lot of reasons for this !) just overbuild use bigger thicker materials. however another consideration is mounting holes elongating and or wearing out. Engineering mounting points can address this.

Steve S was talking about galvanic corrosion,where I work we manufacture marine closures ,(hatches doors windows) galvanic corrosion is a concern for sure! For galvanic corosion to occur 3 items need to be present: metal A near metal B and electrolyte . Galvanic corrosion can be stopped by removing one of these or isolating the one or both of the metals. At work we use a liberal amount of teff-gel a Teflon based dielectric grease. But also a lot of plastic washers, anodized parts and other isolators. Obviously A lot of problems can be avoided.

Stainless steel could be a practical alternative .but beware stainless steel can work harden and become brittle, again this can be avoided by overbuilding so that there is no flex and hardening does not happen. Diff mounts come to mind :) .
Also 400 series stainless would be a good choice as it more like mild steel. it does rust but not at the rate mild steel does. It would need to be painted/powder coated.
On the subject of powder coating....... It's good on steel but not good on aluminum in marine applications, any time salt water can get through the finish it will travel under the finish and pop off the coating.
A better way to finish aluminum is anodizing, a scratch In anodizing doesn't travel under the finish because the finish is grown out of the surface of the material not bonded like powder coat/paint. Also anodized aluminum will not conduct electricity. Galvanic cant happen with out current passing .
 

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Great info Mr Llamahead. Thanks for sharing... This is why I love these forums!
 
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