Aluminum tube for Tuber Chassis?

[C*H*U*D]

Originally Posted by jkabee

...If some of you have used aluminum successfully for cages and bumpers, post it and post some pics.

This isn't tubing but rather 1/4" solid rod. This was my first project back when I got interested in crawlers. It's drilled and tapped for 4-40 SHCS. Building an entire chassis is possible, and not very difficult but it does take some time. Bumpers and sliders would be pretty quick I think.

[jkabee]

Wow CHUD. That looks fantastic. Not sure what your day job is, but you appear to have quite theknack for tubers. Looks petty strong too. I imagine most falls or rollovers are going to occur at 2 feet or less off te ground, so I would think 1/4" aluminum would hold up fine to this, especially at the smal length fr 1:10 scale. I picked up a 1/4" alum tube at Hobby Lobby today and found it to be quite strong (in the perspective of an RC car).

[jkabee]

Came across this product during my research on aluminum weld/braze/solder. Technically, this is a solder due to the fact that it is applied at less than 800 degrees. I haven't read any independant reviews on this yet, but it APPEARS to be the trick for brazing aluminum of any size or thickness. Also, it does not require fluxing whatsoever. It works on any "non-magnetic metal" with the exception of stainless steel.

Dura Fix Aluminum Welding Aluminum Brazing Aluminum Soldering & Repair Rod is not sold on Ebay US or Amazon

There is a great demonstration video on YouTube by an independent source if you want to see it in action.

Durafix Aluminum Welding Rods - YouTube

Hope this is helpful.

[C*H*U*D]

Originally Posted by jkabee

Came across this product during my research on aluminum weld/braze/solder. Technically, this is a solder due to the fact that it is applied at less than 800 degrees. I haven't read any independant reviews on this yet, but it APPEARS to be the trick for brazing aluminum of any size or thickness. Also, it does not require fluxing whatsoever. It works on any "non-magnetic metal" with the exception of stainless steel.

Dura Fix Aluminum Welding Aluminum Brazing Aluminum Soldering & Repair Rod is not sold on Ebay US or Amazon

There is a great demonstration video on YouTube by an independent source if you want to see it in action.

Durafix Aluminum Welding Rods - YouTube

Hope this is helpful.

I believe someone here did some aluminum work with that setup.

[doublej]

Originally Posted by C*H*U*D

Now we are talking....

OK I am going to venture into the engineering and design side, I am self taught at everything but turn wrenches on fighter jets for the AF. But we spent many hours in the pub and around the campfire tossing ideas which has led to many hours reading text books and research.

The way I am seeing it - your main outter tubes (Apillar to Bpillar) solid isn't a bad idea. But the roof cross braces could be tubing to help with weight.
I have been thinking and even ordered 3/16 and 1/8 (need to find something between, 1/8 looks tiny) because that seem to be the normal for crawlers. Even though it doesn't scale out perfect - to the eye it looks pretty dead on.

Strength wise - numbers don't do us much good just like in 1:1 rigs. We arent really talking sheer or laterial stresses. It is the what if of rolling and landing directly on a corner or bend. Will the braces dstribute the load or buckle? This is where you just have to copy what has been learned from 1:1 and know that the weights we are playing with don't scale out to 1:1 rigs and we have more wiggler room.

OK Ill shut up now -

[jkabee]

Well, for the limited investment in trying, I'm all for giving it a shot. Again, there are vast differences in aluminum tubing also. Thick wall aluminum is surprisingly strong, while thin-wall is weaker than a soda can. For the cost of a few sticks and some Durafix or another version I found on eay called HTS-2000, its worth a try. Also, gas could be less expensive, since anything that burns at 800 degree will work. Heck, you might even be able to use Butane (although I won't try that).

Back to the strength vs weight issue. I agree with doublej that we are not talking scale weights compared to 1:1s which is why I feel that a thick aluminum tube will be just fine for strength. Now, am I going to be launching my RC 10 feet in the air like a basher? No. I expect normal rollovers of 2-3 feet or less. On a 6lb rig, that should not generate anywhere nar the force required to bend 1/4" aluminum.

Here is the thick-wall I would use: Round Aluminum Tube 1/4 .049 (4) (k+s3061) K-S Hobby and Craft Metal Tubing

Anything thinner than that and I wuld startto question strength vs weight reduction. I'd just go wth steel.

[doublej]

Thats .049 or 1.25mm wall tube.
Give ya some things to compair too.... After 8yrs in England - mm is easier for me.
For Baja trucks, the smaller rigs must be 1 3/4 OD DOM by .120 or 3.03mm thick for all your main tubes. In England we would use seamed tube but at 6mm thick for main bars 3mm wall for braces.
It comes down to can the tube A) take a hit without denting B) bend before it breaks. You want things to bend basicly. You can always put it in a vise and bend it back. But if it dents on one rollover, then happens to hit the wrong spot on the second roll over - your whole cage could fall in on itself and you have to rebuild it all.

Cause thats what we are really talking about here. How hard can you play before you have to redo something. be it rebending and setting tube work or cutting out and redoing.
I am super hard on my rigs. You say 2-3ft falls, last weekend I rolled down a solid 10ft or more cliff. Thats more normal outtings.

[jkabee]

It sounds like there is only one way to test this. We need to make the cage and throw it off a 10 foot cliff! I'm willing to bet that the plastic new bright body breaks at the connection points with the cage before the cage does! I'll get started on the cage this weekend!

[doublej]

Pretty much my thinking - let us know how ya get on. With some luck I will be cage building next week. See how far I get this weekend.

[jkabee]

Whatever happened to the OP? Did he get tired of us or has he been in the lab, experimenting with that spare aluminum????

[Army RC Crawler]

OP here, sorry I have been away at work. Long hours plus long commute are tough on me and don't leave a lot of time for the wife and child let alone hobby stuff. Add to that outside temps here have dropped below zero so I am not terribly excited to head out to the garage. I have Monday (tomorrow) off so I'll see what kind of mess I can make out in the garage. The wife just brought home a propane shop heater for me!

[doublej]

I can feel ya on the long hours and cold weather. I just dress like I'm back in the snow in England and let the sparks keep my hands warm.

Let us know how you get on.....

[jkabee]

Originally Posted by Army RC Crawler

OP here, sorry I have been away at work. Long hours plus long commute are tough on me and don't leave a lot of time for the wife and child let alone hobby stuff. Add to that outside temps here have dropped below zero so I am not terribly excited to head out to the garage. I have Monday (tomorrow) off so I'll see what kind of mess I can make out in the garage. The wife just brought home a propane shop heater for me!

I'm with you there. My whole weekend amounted to catch up projects around the house and zero time for RC. I am definitely interested in your efforts though. Nice that the wife brought you a heater!

[Army RC Crawler]

Well I just returned from trying to braze aluminum... it didn't go well. I prepared four pieces to make two T-joint attempts. I wanted to make a braze joint with the Ace Hardware aluminum flux solder kit, then try again with silver solder.

The aluminum solder kit came with "flux" if you can call it that, it was more like blue dye. It was thinner than water and dripped off the metal leaving nothing behind. I don't know if that was because it was super cold or what. I tried the solder anyway and all it did was bead up in a ball and drip off as well. When I got it to stay on the aluminum tube it was still beaded up and I never got it to penetrate the joint. It broke instantly. I cleaned everything off and retried using the silver solder flux, the aluminum solder still beaded then the tube melted. Going back to the directions on the package, "if braze does not flow freely, the surfaces are not clean or heated to a high enough temperature..." then it says to clean again, apply more flux "liberally" and reheat.
**As a side note** It says that the solder melts at 1070* F, .062" diameter.

With the second pair of tubes I prepared I prepped it as if it were steel. I cleaned the tube thoroughly and fluxed the joint with Harris paste. When I heated it the flux didn't seem to melt to liquid like it should and the silver solder only beaded up again not penetrating or flowing at all.

So, fail, then fail, then fail again. I even brazed a couple pieces of steel brake line to make sure I wasn't crazy. It went perfectly with super smooth solder joints.

[Army RC Crawler]

...so did I get bad flux? Is it supposed to be blue water/dye? Was it too cold? Is it impossible to braze aluminum tube? Am I crazy?

[MaD222]

aluminum has to be VERY clean, to weld, i weld it every day, not much help for you sorry, never brazed it, not sure if you can, but when i weld, if theres anything on the surface it makes it alot harder to weld. try wire brushing the surface, clean with some acetone, then flux, who knows......

side not, im also doing a similar project, just waiting for my tubing to show up, but im tigging it up, there will be a hilux thread in the 1.9 section to showcase it

[doublej]

This may sound dumb but I hate brazing so it's all I can add really.
Have you searched YouTube - there are usually 100 different people showing how todo things. That would let you see exactly what someone else did vs someone just trying to type it out. I'm on my phone atm or I would look.

[MaD222]

looks like flux core brazing rod, and oxy/acetylene i think, but he doesnt say, could be oxy/mapp? i dunno, never had to braze it before, now that i see it, i want to learn it, to say i can do it too!!

Brazing Aluminum - YouTube

[Army RC Crawler]

Originally Posted by MaD222

aluminum has to be VERY clean, to weld, i weld it every day, not much help for you sorry, never brazed it, not sure if you can, but when i weld, if theres anything on the surface it makes it alot harder to weld. try wire brushing the surface, clean with some acetone, then flux, who knows......

side not, im also doing a similar project, just waiting for my tubing to show up, but im tigging it up, there will be a hilux thread in the 1.9 section to showcase it

When you start your aluminum project let me know I would like to see it.

I will clean the tube with some Iso Alcohol and try again.
The more I think about it the more I think the flux is bad. If aluminum is so difficult then I am sure good flux in the joint is a must. With the kit flux being like water I can't see how it would work at all.

[trwelds]

Thing with aluminum is the oxide layer has a higher melting point then the pure aluminum inside. Often people have a molten core before they get the outside hot enough. The use of High freq TIG is to break this oxide layer in one half cycle and weld in the other. You will have to clean it very well to weld it. Also aluminum will spread the heat down the peices a lot more, I believe roughly 6 times as much as steel this is why it is used in heat sinks and rads. But this also makes it harder to work with because it takes a lot of heat input to get the spot weld ready and then has a low melting point so the window you have to work is tight.

Some of you mentioned a nice TIG machine to do this but it still would take a lot of skill. I have a Dynasty 200 DX and can weld pop cans together and I would find this hard to do, I think. Solid rod maybe a better choice just to work with. Also low grades of al are dificult to weld. Some of the stuff you find at hardware stores is extremely hard to weld I have found while spending the money to get a good 5+ grade will be to your advantage. But then the problem will be micro fractures during bends.

Generally if it bends nice, it welds bad. Bends bad, welds good. Trial and error with the grades will be what makes or breaks the build, in my opinion.

/edit/
I just did some research into this and it seems like most of the flux is acid and water soluble, thus making it more watery. The problem you might be having is that if your flux is not acid and your trying to weld 5000 series or greater alum its not doing what it needs to do or if it is acid and your using it on 4000 and lower its also not going to work. Also if it is acid it will corrode your project and greatly weaken the alum. You will have to clean it inside and out to prevent this. if you use tubing you'd have to boil it to clean the insides out ect.

solid rode may be the better option. Also it suggest using a carbonizing flame to do this.

Hope this helps some.