Pros and Cons of Aluminum

With Worlds done I would like to ask everyone how their experience with aluminum was. My team only had steel to work with which made our robot very heavy and caused a lot of overheating issues and twisted axles. I would like to know the following to help decide whether my school should invest in aluminum for this upcoming year.

  1. How much aluminum did you use? (ratio)

  2. Did you have any strength issues?

  3. Where there any other differences from steel (not including weight) that you noticed?

  4. What was your overall opinion of aluminum, love or hate it?

Thank you very much for your time and input :slight_smile:

maybe half of our bot was aluminum and no we did not have any issues with strength. if it is bent though, it will break off much easier. i didnt find any difference from steel other than weight, but aluminum is MUCH easier to bend so if severely abused it probably would break. i really like using aluminum and any time you are using and arm or trying to climb like in round up aluminum is a great way to go.

I’ve never seen an aluminium part fail where a steel part would not have. The parts are DRAMATICALLY lighter and very useful too. The only reason not to use aluminium would be price reasons (i.e. you can’t afford multiple $100 kits).

If you’re sitting on cash - buy aluminium. If you’re not, fund raise and BUY ALUMINIUM.

i would completely agree with that!

  1. Everything except for our linear sliders was aluminum. We tried to make aluminum sliders, but the aluminum was irregular because of the holes and tended to spall.

  2. 254A did not have any strength issues with the aluminum. If used correctly, you shouldn’t notice a difference in strength between steel and aluminum. If used incorrectly, aluminum tends to bend easier than steel, which can cause it to become significantly weaker or break.

One of 254D’s arm joint axles almost pulled through the aluminum rail that it was in, but that was an extreme case, because they lifted their entire robot through that axle. It did significantly increase the hole size in the direction that the arm was pulling.

  1. Aluminum tends to not slide as well on things as steel because it is softer and will dig in more. Aluminum is also far easier to cut and work with.

  2. We love aluminum and it is a vital part in making our robot work in that some of our designs just wouldn’t work with the heavier steel pieces.

  1. Everything except for the rail that supports our whole tower and the lower c-channel on our double-bar link is aluminum. The rail that supports our tower could have been aluminum, but it was built when we did not have any more aluminum parts and it would be a pain to replace. The bottom large c-channel on our arm is steel because back when we used rubber bands to hang, it bent the aluminum c-channel.

  2. Aluminum is weaker than steel , but unless you are putting a lot of stress on it you should not notice it. We had one aluminum rail break when it was shipped to Orlando. You could see the stress fracture and where the aluminum stretched before it gave. We had one more aluminum rail with us, but it was bent in the middle, and when we tried to bend it back, it broke the 1-wide part of the rail. We “splinted” it with a strap, and then it was fine.

  3. Do not bend aluminum at one point more than once. It’s like bending a paper clip 20 times.

  4. We think aluminum is great because it is about half the weight of its steel counterpart, despite being 50% thicker. It allows the construction of robots that are just as strong as steel ones, but with much less weight bogging down the motors.

This quoted post is similar to others in the thread. It appears to contradict itself.

I think many folks are trying to be too black or white about this subject, and are making a mistake.

(My) Bottom line: The aluminum parts are weaker than the corresponding steel parts. :frowning:

(My) Other bottom line: The aluminum parts are 40% of the weight of the corresponding steel parts. :slight_smile:

(My) Final bottom line: The aluminum parts are excellent items to have in your bag of tricks, but they complement the steel parts rather than 100% replacing them. :cool:

(My) Postscript: The aluminum parts aren’t cheap.

As far as Vex goes i find that 90% of the time (for me at least) the steel parts are way overkill strength-wise. I built my robot completely out of aluminium this year with no problems at all.

Sure there are some situations in which you really do need the strength of steel or you need to brace the aluminium so much that you may as well use steel however i find these situations to be incredibly rare.


Both of those still hold true. Where I may use a steel rail, I could use an aluminum c-channel for comparable strength. You wouldn’t use aluminum pieces to make a robot that is just as strong as a steel one with the same number of pieces. If I were making an aluminum drive base, it would have more standoffs or other metal supporting it than if I were making a steel one, because the aluminum needs more support to keep it from bending.
You could make an aluminum robot that is functionally just as strong as a steel one, and it could still be lighter.

There’s a balance in everything :slight_smile:

It is not the materials that make your robot heavy/overheat/twist axles, it is your engineering tradeoff choices.

I find most VEX robots are wildly over-built. For the forces involved, it doesn’t take much of either steel or aluminum to build a stiff, strong structure. Exo has always been about light weight and speed, so our students build robots that are just about all aluminum. Within the context of VEX, the pros of aluminum piece are the light weight and greater stiffness and the con is that it costs more.

This year both of our bots were all aluminum/polycarb/pitch metal; 2438A was 10 lbs and 2438B was 8 lbs. Neither had strength/breaking issues (we had more problems with the motors than anything, haha). 2438B had some pushing matches at Worlds and was fine. We love aluminum (and polycarb!!) and only use steel for prototyping, really. The problem is that aluminum is expensive…

Sorry for not stating this initially. We believe steel is the reason because we designed our robot around others. My team is fairly new and looked at other robots to see what they were capable of. Our arm was designed another team’s to which we talked to them and they never bent axles and they believed it was because of steel. As for the overheating motors, while it may be many things all teams we asked said lowering the weight would help.

aluminum can definitely increase the capabilities of a bot and it should not cause it to break because it is strong enough if not abused.

We try to replace all our steel parts with aluminum except for places that we need to have an actual single bars or plates. The aluminum flat pieces bend way to easily for us. In many cases we will replace steel flat pieces with aluminum that is ripped to be 1x1 L, this makes it much stronger in compression compared to the steel flats. Also, several of our cross members have stayed steel because we don’t want our chassis to bend, we also like it because it kept weight low for our center of gravity.

The aluminum is expensive but when you are trying to keep your robot under 10lbs it’s the only way to go.

I also like aluminum because it is so much easier to work with, we can rip aluminum pieces on our band saw more cleanly than their steel counterparts.

we replace our steel with aluminum after the bot is already built so we can make sure that we actually want to use the metal we want to cut

Ah, “designed around others” == Copy the layout without copying the materials.
Thats one possibility. Other common ones are “luck” and “craftsmanship”.

Now that you’ve been to Worlds, you have had a lot of opportunities to learn.
Have you heard JVN say “Design is an Iterative process” yet?

No I have not heard that saying before. (I am new to the forums, so if it is said on here thats why)

When consulting other teams we discussed ratios, how many and what type of motors but I never brought up type of metal. I only recently learned about aluminum at Nationals.

Also I don’t want to directly copy other robots (learning is half the fun) I would look at concepts that worked and then implement them on our own to our current design if possible. This may have also lead to issues.

I thank all of you who are trying to help me find the actual source of the problem by explain what other sources are, but I posted this to learn about peoples opinions and experience with aluminum. I will keep what you have said about the other possible issues in mind with the construction of my teams next robot :smiley: