pic: Team 2502 Chassis Teaser

[Jeffy]

Originally Posted by Techgirl675

For sake of comparison our chassis with 4 CIMs, mechanum wheels and all 4 gear boxes is less than 35 pounds...
For what it's worth, we've gone the 80/20 route. While it's great for prototyping and testing, we've found it's far too heavy for competition use. We've since switched to welded thin-wall steel tubing and it seems to work quite well.

WOW!
4 Cims is 10 Lbs.
4 6" Mecanums is 6.2 lbs.
4 gearboxes is anywhere from 6-10 lbs.
Making your frame only
12.8 lbs. max

Our frame is pretty bare essentials out of aluminium and its at 18lbs.

[Techgirl675]

Originally Posted by Jeffy

WOW!
4 Cims is 10 Lbs.
4 6" Mecanums is 6.2 lbs.
4 gearboxes is anywhere from 6-10 lbs.
Making your frame only
12.8 lbs. max

Our frame is pretty bare essentials out of aluminium and its at 18lbs.

We have a welded steel tube chassis and it is only 10 pounds including all of the supports.

[keehun]

Originally Posted by Techgirl675

We have a welded steel tube chassis and it is only 10 pounds including all of the supports.

That's pretty cool. Though I honestly don't know why it has to be that light for it to be considered a "good" or a balanced robot

[Techgirl675]

Originally Posted by keehun

That's pretty cool. Though I honestly don't know why it has to be that light for it to be considered a "good" or a balanced robot

It really doesn't need to be, it just happens to be what we decided to use for strength and the light weight.

[Jeffy]

Originally Posted by Techgirl675

We have a welded steel tube chassis and it is only 10 pounds including all of the supports.

Would you mind sharing the size and alloy of the pipe?
We have aluminum and steel welding machines here. and steel welding is so much easier.

[Techgirl675]

Originally Posted by Jeffy

Would you mind sharing the size and alloy of the pipe?
We have aluminum and steel welding machines here. and steel welding is so much easier.

Last year we used 1 inch steel tube and this year it is 3/4 inch with 1/2 inch supports. Everything holds up great!

[keehun]

Originally Posted by Techgirl675

It really doesn't need to be, it just happens to be what we decided to use for strength and the light weight.

Haha cool. Sorry if I sounded like I hated you or something. I don't!

But someone earlier brought up low CG -- and yes, that's one of our main focuses. We are doing direct drive with Banebots Planetaries and we're trying to achieve super low CG.

[dragon72950]

Originally Posted by keehun

I will weigh it this coming monday.

And we do have a very interesting wide-configuration that will be super weird but we hope to have work out!

And no swerve this year. We thought that whatever we could make would have too low of a clearance to go over the bump.

Hm, did I give too much away?

well interested to see how much it weighs

[Dave McLaughlin]

One of the heftiest frames I have seen this year.

Originally Posted by Techgirl675

Last year we used 1 inch steel tube and this year it is 3/4 inch with 1/2 inch supports. Everything holds up great!

I'd be interested in the wall thickness and alloy you are using as well.

[JamesCH95]

Originally Posted by Techgirl675

We have a welded steel tube chassis and it is only 10 pounds including all of the supports.

Welded 4130 steel (maybe 1020?) is probably the lightest possible frame construction barring composites, which are cost-prohibitive for FIRST. Alloy steel is better than 6061-T6 aluminum in nearly every regard...

I've made FSAE car frames with largely .065"/0.045" walled round tubes. 0.035"x0.750" square tube would be plenty strong enough for a FIRST robot. And no strength loss from welding FTW! Unfortunately my team didn't have the facilities to make a frame like that this year

[team1718]

Originally Posted by keehun

How heavy is heavy? With gearboxes, motors, electronics, the calculated weight is 50lb...

And I can lift this with one arm. Easier to lift with two arms..

your really going to regret using 80/20

[EOC]

Team 1208 loves 80/20.
Our completed robot this year has a kicker, lifter, ball collector and climbs the bump. It just weighed in at 116 pounds.

[EricH]

Originally Posted by team1718

your really going to regret using 80/20

Can you provide a reason for saying this? If you have a valid reason (bad experience, finicky connections, stuff like that), then by all means post it. If you're just saying this to say it, then it might be better not to say it.

[keehun]

Originally Posted by team1718

your really going to regret using 80/20

We've been using 80/20 since our rookie year without a problem. (Well we've had problems but it was a human-fault). So any evidence or warrants behind your statement?

[Bob Steele]

80-20 can be a fine material to use for a frame
so can many other things... One of the neatest things in FIRST is that there is no ONE RIGHT WAY to do anything!!

My own experience with 80-20 was from my own mistakes early on...
I didn't make sure everything was always tight.... or use lock tite on the connections... When my old team started using 80 20 by bolting through and making our own brackets we had much better success...

I really like the comments I am hearing about using steel tube... I think we will investigate that next year.... sounds like an interesting solution....
thinner steel vs thicker aluminum
Ease of welding.. vs difficult welding...

Worth looking at.... it must work.... thousands of bicycles and cars use it

thanks for the great suggestions...

Your 80-20 frame looks pretty cool!!!

good luck and we will see you on the field!!