Our team needs to add some ballast to our robot, and we’re trying to decide if we can use some donated sash weights from old windows. Does that count as a COTS part? What about weights from old barbells? What does your team use for ballast?
Thanks!
Whatever you do, don’t use bird shot as ballast.
#crossroads2014
Ballast?? How nice it would be to have to add… In our 5 years we have only had to add weight once… And we used steal bar since it was easiest to weld on attachment mounts.
I am interested in what others have to say about this…
Good luck!
Aloha.
A table top vice clamped to your frame works nice…
Weld all your scrap metal together and duct tape it to your robot. That works right…?
Extra batteries, oh wait… :rolleyes:
Our team melted old tire weights we got from an auto repair shop and filled 1x2 aluminum tubing with it. An 8" piece ended up around 4 pounds when done. Worked well for us and is easily mounted into the chassis plus it fits with the theme of the game…right? Reuse and recycle.
In loose thin pooly attached plastic baggies that is. :eek:
I hear bench press weights work well.
We haven’t to add extra weight on our root in FRC but our one of our BEST teams needed to add extra weight, they added 10 lbs of pennies. We might just add 10lbs of pennies if we need it.
In 2013, we zip-tied a .5"x18" steel bar to the back of our robot. Basically any easily-mounted steel object will do just fine.
On the BOM do you list the pennies as a whole, or are they exempt because each one is under $1?
We were going to use 3 or 4" PVC pipe with a cap glued on one end and a spin off on the other, and fill with sand. Easy to secure and you can adjust the amount of sand if needed. Oh and easy to source and cheap!
Re-position the battery to shift the robots center of gravity. Otherwise a chunk of steel should do the job
Be careful when using sand per R8-J. I don’t interpret that as a hard ban on sand, but it’s definitely not legal if it can get all over the field.
On the subject of adding pennies for weight (which I actually suggested to my team on Sunday, half jokingly, but for decoration instead…):
1 penny = $.01 = 2.5 grams
1 Nickel = $.05 = 5.0 grams
1 Dime = $.10 = 2.268 grams
1 Quarter = $.25 = 11.340 grams
1 Pound = 453.592 grams.
This means to get 1 Pound of ballast weight using each common U.S. coin, you would need:
Pennies: 181.4368 = 182 = $1.82/lb
Nickels: 90.7184 = 91 = $4.55/lb
Dimes: 199.9964 = 200 = $20/lb
Quarters: 39.99929 = 40 = $10/lb
(Source: http://www.usmint.gov/about_the_mint/index.cfm?action=coin_specifications)
Therefore, the most economical coin to use as ballast would be pennies. But if you really want to show off, use Dimes!
Even more fun: You can probably get MOST of those pennies for free…have every student check under their couch! 
Or, if you are really rolling in the dough, use the Presidential or Native American $1 coins, needing 56 to make just over a pound!
We had discussed that, but weren’t worried about making a mess. Plus we are right at 119lbs with out battery or adding weight so even more of a non issue.
I suggest a cast iron bust of Mr. Kamen himself. Perhaps a second one of Mr. Flowers if need be.
A nice length of 1018 steel is a good choice, but you need to drill holes which makes it non-cots.
Other ideas I’ve seen (but don’t necessarily endorse):
Sand in sealed PVC pipe
Sand in black pipe
Cast scrap metal blocks
Concrete casting
Kitty litter (Dallas 2009)
It doesn’t have to be COTS to be used as ballast. If it is not on the prohibited materials list it is fair game. Some of the things that are not allowed are lead unless it is fully encapsulated so there isn’t any skin contact or a way for dust/chips to be generated. Things like pennies, washers, ball bearings or other loose items must be in a robust container so that they will not dump all over the field if the robot tips over.
So the question is what are the sash weights made of?
The rookie team I am helping out is using sash weights as they are at a very old school and there is a stack of them in the maintenance shop. They are cast iron, though that doesn’t mean yours are.
We had a steel bar, roughly 2x4 and we would cut off pieces as needed. We let a few teams take some pieces at various competitions, let’s just say the machine shop wasn’t very happy with us. Milwaukee couldn’t cut it so we had to take it to the college across the street to cut.