Sheet Metal Fabrication vs. Using Channel

I have seen both used before, I just want to know if one is in any way better than the other. Or just the benefits of using one over the other.

We’ve used sheet metal for a couple small parts.
It lets you cheesehole like crazy to get rid of material that doesn’t really help strength anyway if a sponsor does it. Channel is faster to source though.

It really is dependent on many factors: resources, time, designing capabilities, experience, etc. WildStang has recently worked with two sheet metal manufactures to make parts for our robots. This year, our bot was almost entirely sheet metal, apart from most parts on our lift. Channel is useful for many things, you just need to use it right. I’m not going to get into much detail about this, or start a war. You may want to look at older threads that explain pros and cons of both.

The best way is using the resources at your disposal. Both require different design methodology, but both will get the job done.

For the last 6 years our drive train was c-channel. We have done one and two level chassises for complex designs.
The channel is quick to put together snap together, easy to mount to(just need to make spacers for the inside so it clod rant get pinched), and not all to heavy.(can always still wide holes to take out weight)

We may switch to sheet metal or tube design chassis next year if we can get access to the cnc machine.

The biggest difference is that most teams using C-channel or other extrusions are typically doing most of the individual part fabrication inhouse, where most teams that do primarily sheet metal construction have their parts produced in partnership with an external sponsor. This is a very different approach to fabrication, and it works very well with certain resource sets (and not well at all with others). I wrote at length about the process, and why our team uses it, here.

Your post that you linked is really great. On a similar note, how do you get your students interested in CAD? It’s one thing that I think could help us greatly but no one wants to implement it.

A 3D printer really helps here. There is just something about drawing something in CAD, then holding it in your hand a short time later.

Do you do large scale 3-D printing? Or just small stuff? I know of a team that 3-D printed a whole chassis with carbon fiber and fiberglass infused filament on an 8 foot by 8 foot printer platform.

Do you know what team that was? Because that sounds awesome and I want to figure out how they managed to get the resources for that haha.

The team is 3824. They discuss the process in this thread. Here are their robots from 2012 and 2013. They are really awesome.

Sheet metal frames allow you have a much lighter but equally strong chassy/robot compared to slotted tube, however sheet metal is harder to fabricate (bending it correctly) and can be dented easer, though i would definitely use sheet metal if i ever get the chance.

also note that by making the base out of sheet metal you have also move the robot/s center of mass much higher, thus making it more flip prone.

Why would you have to move the COM higher?

when reducing weight of your foundation you cause it’s COM to be to a heavier side, so if i take weight off the bottom and add it to the top i now have a pendulum

it’s due to that fact that your weight lemit is 120 so by reduce your chassie weight by 20 pound and now you added it to the top of the robot, you will be more likely to have more mass at the top of the robot and is more likely to tip/flip

if this needs further explanation I’ll reply when it’s not 2:14 AM lol :slight_smile:

I can only see this being a problem if you have a tall robot (above 60" or so)

All he is saying is that if you take weight from the chassis and put it into a system that is even half an inch higher, you have raised your COM. Depending on your robots design, this may not be an issue.

Oh, okay.

It would depend on the game more or less. Sheet metal allows much more flexibility in shape to allow the robot to better fit the game piece(s). If it’s a game heavy in defense, I would want the sturdiest bot on the field to withstand pushes of other bots and push others with ease, not having to worry about any weak points whatsoever.

:rolleyes: Seeing lots of generalizations here such as “sheet metal is lighter than tube” and “sheet metal is weaker than tube” ect. ect.

Both sheet metal and tube’s weight are totally dependant on how you use them.

Well, yes, but you could just lose the weight completely and not even put it into a different system. You would just end up with a lighter robot in general.