Re: Methods of adding ballast to underweight robots
 

To add to Al's pneumatic suggestions, the brass fittings can be screwed together and can add a lot of weight fast.

Re: Methods of adding ballast to underweight robots
 

It will be interesting to see teams using pennies and listing them on the BOM.
Ex. 2000 copper or copper/zinc one cent US or Canadian coins Undepreciated Cost $20.00

Re: Methods of adding ballast to underweight robots
 

If you can find a gunshop that will loan you a bag of Tungsten shot, that is about as dense a material as you'll commonly find. Costs about $30./lb. Lead shot is much cheaper. An old bicycle inner tube partially filled with shot or old wheel weights and tied up like link sausage should be pretty easy to strap on there somewhere.

Re: Methods of adding ballast to underweight robots
 

We found (and used) a 1" square bar of bronze which weighs 0.17 pounds per inch. Last year we used about 8 pounds of it, this year about half that.

large copper wire - like 600 MCM - is heavy and relatively inexpensive. We have an 8 inch piece which weighs about half a pound, maybe more. If you know an electrician, maybe she will loan you a few feet - but give it back after the season, or pay the scrap value to them at least.

I hear small pieces of railroad track are heavy...

Re: Methods of adding ballast to underweight robots
 

We're using pieces of steel we had laying around as "armor plating"

Re: Methods of adding ballast to underweight robots
 

loads of metalshavings ... in your victors... jk

Re: Ballast Confusion
 

In the safety manual they ask teams not to use lead solder at events.
Wetzel

Re: Methods of adding ballast to underweight robots
 

I had hesitated to include this in my first post, but robot rules do not prevent you from mounting unused 2009 KOP motors as ballast. Use the mounting holes and hardware meant for the motor, just tie off and insulate the wires so that they don't come in contact with any active circuitry.

Re: Methods of adding ballast to underweight robots
 

It had been alluded to earlier in the thread, but keep in mind that ballast is a great way to move/control your center of mass. Where you place it will have a great impact, and can be used to improve robot control, improve acceleration, and prevent tipping.

Also keep in mind that this brand new weight will change your robot handling, and your drivers may have to re-learn how to drive the robot.

Re: Methods of adding ballast to underweight robots
 

Don has the same idea we did. We used 1" diameter brass rod because it is what we had around. It looks very sharp when polished up and was easy to mount pretty much anywhere we wanted. One rod runs along the back of our base and weighs about 10lbs. The other rod runs near the front and weighs about 8 lbs. In the end I would recommend this method for adding weight due to the ease of mounting and the nice look it adds.

Re: Methods of adding ballast to underweight robots
 

3119's robot weighed 60 lbs. Two 27" 2" diameter steel bars (23.4 lbs each) got the weight up to 116 lbs. Ain't a thing of beauty that's for sure.

I would have preferred to mount the bars in a tray so they could roll toward the back (on start) with springs or compressed air to return them to the front. Moving an object is function of moment of inertia. And traction is a function of mass. So the rolling ballast will lower the moment of inertia and allow more power to be dumped at the start.

Re: Methods of adding ballast to underweight robots
 

At the Dallas regional, there was a robot that used bags of cat litter for ballast. Basically it was a driving chassis with one of the kt tubs attached and two 20 pound bags of cat litter inside the tub.

They got the judges award :)

Re: Methods of adding ballast to underweight robots
 

If you use barbell weights or free weights, make sure they can't fall off. One slipped it's zipties and fell off the frame; it immediately became a very effective anchor. The wheels had no hope of overcoming the friction of the weight.

Re: Methods of adding ballast to underweight robots
 

We had this happen a few years ago at Peachtree. I think it was 2005. A team used a large container of BBs to add ballast. It ruptured. We spent the rest of the weekend picking them up :( Spilling a bunch of shot on the floor at the inspection station while adding it to your robot will not make you real popular, either.

Make absolutely sure that any container of shot is durable, secure, and sealed. I can promise you that any robot at 10,000 Lakes using shot for ballast will invite extra attention at inspection.

The best method I have seen so far this year for adjusting weight at the scale is to add some pieces of threaded rod to the robot, and bring a bucket of washers that fit over them. Add washers to the desired weight, and then put the nut on the rod. Use big rod, like 1", and the washers will also be big and substantial weight. If you are way under weight, bolt on some of the heavy stuff mentioned earlier in this thread to get you close. I've always been partial to barbell plates.

And the best thing I have heard of so far this year for ballast is an arbor press, borrowed from another team in the pits...

Re: Methods of adding ballast to underweight robots
 

What my team does is we take weights out of a weighted ankle band (just ask for one at sports authority or D(stupid censor)icks they will find it for you) and just drill holes in them and zip tie them somewhere safe. Its great because they come in 1 lbs increments so you can add just enough.