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#16
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Re: Types of Metal
We on 33 have been doing a folded sheet metal chassis for the last few years. Once you learn how to work with sheet, it is pretty easy, very light and very effective. You do need to learn rivet techniques and how to bend metal accurately an effectivele. We use heat treated 6061 T6. Before everyone tells me you can't bend it, that is not true. Heat treated (T6) means you need to be very careful bending it and use an ample radius.
For the big structures we have generally been going with space frame welded aluminum tubing both square and round. I have a lot of race car chassis construction experience so it helps. One of our students did most of the welding this year. While she is not a pro, she gets the job done. What material you decide to use depends on budget, equipment, and skill sets. 80/20 or Star bar is very easy to use but extremely heavy (from a KB33 perspective). 1/16" is the beefy stuff on our machine and we often go down to 0.035" wall round tube. If you do not have a skilled welder, I would recommend visiting the Team 1216's website and check out their chassis. The pre-drill 1x1x1/16 box with a very specific hole pattern. This technique gives 90% of the strength of 1x1 box with the flexibility of Star-bar or the kit rails with a TON less weight. These guy are pretty modest and only went to 1 regional so you won't see a lot of buzz about them. As a structures guy, I have a lot of repect for this technique as it has the 4-way threat of strong, lightweight, flexible design, and easy to use/manufacture. Another good source are the 2 "Behind the Design" books. You can almost tell what line of work the sponsors are in by the construction of the robot. With aircraft companies you will see a lot of sheet metal. Nasa and Robotics related sponsor teams seem to have a lot of CNC. Big 3 teams seem to have a lot of welding. As far as material sponsors to order from Aircraft Spruce has an awesome selection but can be a bit slow to certain areas. They have some truly amazing materials line a strut material that is 11oz. for 8 feet. Online metals is a good plae to order small quantities, but were extremely slow on their delivery for us (I did find a way to expedite future orders). Mcmaster Carr is fast but expensive. |
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#17
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Re: Types of Metal
I was mistaking 80/20 for starbar.
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#18
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Re: Types of Metal
ttldomination,
I sent you a pm. Just get in touch with me and we'll discuss some things. |
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#19
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Re: Types of Metal
Bleh, the less 80/20 that's used on a bot the lower my blood pressure is. It leaves too much room for last-second decisions that haven't been thought through.
We've used 1/16 wall 1x1" 6061 Aluminum tubing for our frame for 3 years now. It's always been welded. We have students that practice welding on our prototype frames, then they assist the pros who do the welding of the actual frame during build season. From there the frame goes straight to powder-coating at the same sponsor, which also adds strength and rigidity to the frame. Our drive base frame this year came out to 6.1lbs after powder coating, and had zero CNC work or cheese-holes added to it. In future years we will probably experiment with 1"x1/2" tubing that has a 1/16" wall and sturdy injection foam in order to produce a more compact frame. |
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#20
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Re: Types of Metal
1501 has used Chromolly tubing on our past two robots. It's light and strong. We gas weld it, but I believe you can use better methods of welding.
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#21
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Re: Types of Metal
Quote:
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#22
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Re: Types of Metal
What place do you buy from, and how much does it typically cost?
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#23
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Re: Types of Metal
Amen. I would love to see more teams use chromoly.
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#24
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Re: Types of Metal
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#25
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Re: Types of Metal
I'm pretty sure that 1501 welds their tubing, instead of brazing it.
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#26
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Re: Types of Metal
What, exactly, is "ITEM?" I can't just google it cuz I get a million results about video games.
Our team has been extremely reliant on 80/20, with 1'' tube stock where we need to decrease weight. We're building a new robot cart this summer, and I was wondering what you guys would suggest to carry a much heavier load than a FRC robot would be expected to stand up to. Most of the guys are leaning towards 80/20, but I'd rather avoid it because of cost, durability, and weight. Also, where do you get chromoly? Last edited by m3ch4num470r : 31-05-2008 at 16:31. |
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#27
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Re: Types of Metal
Quote:
http://www.item.info/en |
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#28
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Re: Types of Metal
Quote:
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#29
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Re: Types of Metal
Don't tell the Canadians that...
-Vivek |
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#30
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Re: Types of Metal
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