Overweight!?

[Jordan2389Diaz]

:cool: My team now is five pounds under weight and we still need to add some more parts to our robot. We are thinking of making swiss cheese of our metal in order to lessen the weight of the robot like we did last year when my team got to the competition we were fourteen pounds over weight.:cool:

:confused: How many teams are almost over weight - or going to be over weight when you finished your robot?:confused:

Lord is my Shepherd I shall not want.-Psalms 23

[Sunshine]

2.9 pounds over weight at the moment.

[dodar]

Our team is like right around 118lbs and thats what we usually end up at, it is good to guesstimate your weight for each object going onto your robot so you know how to fix it easier than making your robot holy

[Daniel_LaFleur]

:cool: My team now is five pounds under weight and we still need to add some more parts to our robot. We are thinking of making swiss cheese of our metal in order to lessen the weight of the robot like we did last year when my team got to the competition we were fourteen pounds over weight.:cool:

:confused: How many teams are almost over weight - or going to be over weight when you finished your robot?:confused:

Lord is my Shepherd I shall not want.-Psalms 23

Be very careful when swiss-cheesing your robot.

The Last few years, bumper-to-bumper contact was the only contact that was going to happen.

Not so this year. You will see hard impacts at various angles going over the bumps, robots driving on top of other robots at the bump, robots falling off of the bar ... possibly on top of other robots. This year will be very physical. Expect large forces in directions that we have not seen in many years.

In other words, build it robust. And if you do swiss cheese your robot, understand the weaknesses you create, where you have created them, and how you will avoid forces at those points in those directions.

[Ben Martin]

We are about 12 pounds underweight at the moment.

It doesn't really help at this point, but the best way to prevent this is to always be somewhat conscious about weight as you build it and don't create extraneous superstructure.

Take advantage of your bumpers -- they will help reduce shock loads you receive from the sides, so you can cheese your aluminum somewhat in that 5in of space.

[Jordan2389Diaz]

:cool: Do not worry my team is only drilling holes in the metal where the structure tension is not involved and hopefully we are under weight or right on the mark plus our robot is stable.:cool:

Lord is my Shepherd I shall not want-Psalms 23

[IKE]

Before Swiss-cheesing, please read the following paper:

http://www.chiefdelphi.com/media/papers/2220

That being said, "lightening" holes are not a bad idea, just plan them out. Last night we swiss-cheesed a set of components. to give you an idea of the effort, 48 1" holes through 1/8" aluminum was worth about 0.48 lbs This took a significant amount of time and made a huge mess, and as far as i know, that kid is still deburring the parts...

1" hole = (.5^2)*pi = 0.785 in^2
x1/8" thick = 0.1 in^3
Aluminum is 0.1 lbs/in^3
thus each hole is 0.1*0.1=.01 lbs
x 48 holes = 0.48 lbs.

Note that larger holes do have more area, but you can make fewer of them. a 1.5" hole would remove (1.5)^2 material or 2.25 times as much material, but you can only drill 2/3 as many holes. Thus for the components we were looking at, we could do 48 1" holes, or 32 1.5" holes. The 1.5" holes would have been worth 0.8 lbs (.28*2.25*(32/48), but would have reduced the structural integrity of the component too much. this exercise took 10 minutes to do and saved us from scrapping components that had 10+ man-hours in making.

Please drill responsibly!::safety::

[Ken Leung]

Yup, we are currently about 10-15 lbs overweight. We should be able to cut 10 lbs right off the bat, but it's questionable whether we will be able to keep all of our mechanisms at the moment...

[MrForbes]

Weight? good question. Last we checked we were at about 90 lbs, with more parts still to be added.

Our new wood electronics box has 6 lightening holes, the pieces we took out weigh almost half a pound. 3" holes in 1/2" plywood. It had more to do with moving the CG forward, than with reducing overall weight.

[Jon Stratis]

Overweight? With the increase to 65 lbs in the withholding allowance... we're planning on withholding our entire robot!


All joking aside... we've always planned for weight from day 1, and it's paid off. Every year we end up adding steel plates to add weight - in some cases, they're bolted onto the bottom to help adjust our center of gravity, in others they're used as optional structural members (we could have used aluminum, but since we had the weight...). This year, i anticipate being 10-15 lbs under. We'll only add weight if we need to move our CG - other wise, being lighter is going to help with the final hang.

[Jordan2389Diaz]

:confused: What kind of materials did your team make your robot out of for it to be so light.:confused:

Lord is my Shepherd I shall not want-Psalms 23

[thatoneguy23]

Our robot is going to go on it's swiss cheese diet pretty soon. We won't have too much other than frame metal that we can remove either. Just hoping that it works out well.

[Kage]

My teams robot is 99% done...and 15 pounds under weight :ahh:
we are probably going to add some random chunks of metal low-down in the chassis to help with the CoG

[Tom Line]

It is far more efficient to start lightening any steel components you have first. For us, the only appreciable amount of steel we use is in the trannies.

After that, see what you have that you can simply remove or cut off.

After that..... well I hate cheeseholing. We burned through any number of hole saws and drillbits in '08 trying to get down to weight.

[The Megan 2207]

For once we're actually underweight! Last I heard, we were at 65 pounds, but we're expecting to be 80 pounds or so (and this year's robot will FINALLY be smaller than me! :yikes:).

[My-smokepole]

We are running about 6lb heavy right now. ::ouch::
my-smokepole
Team 279

[nitneylion452]

Overweight? With the increase to 65 lbs in the withholding allowance...

Could you point out where the WITHHOLDING ALLOWANCE has been increases to 65 lbs? <R38> still states 40 lbs.

[Jon Stratis]

http://frcdirector.blogspot.com/2010/02/changes-to-robot-ship-this-year-and.html

After discussions with the Game Design Committee I decided that, although Robot Ship Day must remain February 23rd, this year, all FRC teams will be allowed to hold back 65 pounds of their robot’s weight on Robot Ship Day. (That’s roughly half of the total weight of an FRC robot.) Teams may continue to work on the items they hold back and then hand deliver the items to their event. Watch for a team update coming soon.

As Bill just posted that yesterday, i expect the game manual will be updated with 65 lbs in today's update.

[Dick Linn]

I can well remember seeking out free machine shop services to put steel chain sprockets on a diet. Or a couple hours with an angle grinder and a cutoff wheel to spider-web a pair of 60 tooth #35 steel sprockets. Eventually, you try to get in the habit of weighing and estimating as you go.

[Peter Matteson]

Eventually, you try to get in the habit of weighing and estimating as you go.

That's never stopped us from going overweight...:cool:

[Dick Linn]

That's never stopped us from going overweight...:cool:

But then you can at least estimate the size of the drills you need to hog out holes. :D

[rsegrest]

91 lbs with battery...when we weighed the battery it listed at 14 lbs so we figure we're at 76 - 77 lbs...first time we've EVER been this far under :eek: Kind of scary though when you think about possible shoving matches!

[Jon Stratis]

We weighed ourselves tonight - 82.5 lbs. We still need to add:
- cRio
- kicker assembly
- hood/roll bar

We figure with all that, we're still going to be 10-20 lbs light. Which just means we get to use some steel plates again to help position our center of gravity (when the battery is included, we suspect it will be slightly to the back as it is now).

[HazzardFuzzBomb]

Weirdly we are at about 65pounds, we were so shocked when we read it. Looks like someone's robot is getting a nice shiny steel exoskeleton lol

[dodar]

haha we weighed in around 118lbs

[Nigel]

67 lbs sans kicker at last weigh in... we're definitly going to be adding weight low down i think...

[Chris is me]

We are way under, no more than 100 pounds. 120 is not our concern at this point... 65 + removed unmodified COTS items is.

Half of the crate is going to be stuff that can be used as ballast. I wish we weighed more... you'll never hear me say that again.

[dmlawrence]

We lost 10 pounds in the last two days...

[Peter Matteson]

We lost 10 pounds in the last two days...

Did you mis-place your cRio? :rolleyes:

[Jared Russell]

We were at 114.2 last night, with about 5 lbs of parts left to go on.

[killerofall]

My robot is going to need lead blocks- we are at 90 pounds and pretty much done. we have now foregone aluminum in our construction so that we have more weight...

[buildmaster5000]

We were at about 80 before we added our latching mechanism:D :D :D :D hopefully all the other stuff that will ultimately end up on the robot will not put us overweight 10 lbs like last year :confused:

[Smoores]

Well, its a heck of a lot better than our rookie year, where we showed up at the competition weighing 150 lbs. This year we are weighing 100 lbs, and its done. So I guess we can actually use those 25 lb lead weights we had.:cool:

[Hastypickle]

Our robot is 100 lbs and we are 99% done. We first checked the weight last Monday and we were at 86 lbs then. We were so happy that we were so much under.

[PWelsh]

Because of the height of our robot this year we are having no troubles staying under weight. The other night we put everything we had done and everything we think needed to finish plus a little more and we were well underweight. This is my fifth year in FIRST and for the first time i dont see any problems with our weight.

Phillip Welsh
POWER-Storm 2360

[Chris is me]

~95 pounds with no robot cover. A hanging mechanism would probably bring that to 105 if that gets on. If the bumper frame (and hanging mechanism) are shipped, and 4 CIMS are removed to their COTS base, we're within 15 pounds of witholding. I suspect with strategic lightening, shipping of portions of the robot (replace with a spare in the shop, leave spare home to compete), we could get the robot chassis and ball manipulation down to 65. That's kind of a pipe dream, though... There's only so much you can revert to a non FABRICATED ITEM configuration on a robot.

[FlyingHedgeHog]

We're looking at being 10-15 lbs underweight.

[theprgramerdude]

We're at 112 pounds with the battery (no bumpers), so it's around 98 pounds unloaded. We're going to add some small steel bars and 1/4 inch polycarbonate for a cover of the power distribution board and advertising logos, so unloaded it would come to around 110 pounds.

[dmlawrence]

Because of the height of our robot this year we are having no troubles staying under weight.

We ended up with a 17" tall robot weighing 128 lb.

As we like to say, the laws of physics don't apply here...

[BenX02]

40lbs under at the moment. :D

If needed, we're going to ad weights to the bottom to lower our center of gravity though.

[Trent B]

2502 is about 15 lbs under with a few very small parts left to add (we have large things to add still, but we laid them on the bot when we weighed it so they would be included), small parts are basically a few sheet metal things and a sensor or two.

[AcesJames]

176's robot is hovering around 110lbs by our calculation right now. When we get the last few bolts in, and put our plexiglass cover and electronics on today, we'll weigh it all together, and it will *hopefully* be a few pounds under 120. We reached our estimate of 110 by taking all of the robot's pieces we had already made and putting them on our scale. Obviously, not completely accurate, but pretty close for now. Our bumpers, however, are RIGHT at 20lbs. Actually, they might be a few ounces over, but I couldn't tell when I weighed them because our scale isn't digital.

[dodar]

bumpers are supposed to way 15lbs...arent they?

[Jon Stratis]

<R07> G. Each set of BUMPERS (including any fasteners and/or structures that attach them to the ROBOT) must weigh no more than 20 pounds.

A complete set (meaning all the bumpers that are on the robot during a single match - for a typical robot with a kit-bot frame, that would be 4 bumpers, one on each side) can weigh, at most, 20 pounds.

[Michael Ogden]

We are at 86.6 lbs, with a few more trinkets (i.e. the control board) to add, but those don't weigh more than 33.4 lbs (at least I hope not), plus 14 lbs of bumpers. We might actually have to add weight. O_o

[fsgond]

We are at 86.6 lbs, with a few more trinkets (i.e. the control board) to add, but those don't weigh more than 33.4 lbs (at least I hope not), plus 14 lbs of bumpers. We might actually have to add weight. O_o

Bumpers don't add to the weight of your robot. They are taken off and weighed separately. Please read them manual regarding weight and specifications of the robot.

[EricH]

I'm pretty sure that he wasn't counting those.