Ballast Confusion
 

Our robot weighs only 90 lbs fully loaded any suggestions on how to get it up to 120?:confused: http://www.chiefdelphi.com/forums/im...s/confused.gif

Re: Ballast Confusion
 

If you want it to weigh 30 pounds more, you could add 30 pounds of metal to it. I suggest steel plate, screwed to the bottom of the robot chassis.

Re: Ballast Confusion
 

Yup, first thing you should add any braces you feel that would be useful.

If that's not enough, make a trip to Sports Authority and buy a 25 pound weight and put it on your robot.

Re: Ballast Confusion
 

Add another mechanism to improve performance.
Leave it at 90 lbs.
"Forget" to take your bumpers and trailer hitch off for weigh-in.
Find a 25-30 lb chunk of steel and bolt it on.
Add decorations.
Add armor--Lexan works.
Add more wheels (or not).
Experiment with a properly shielded propeller system.

Re: Ballast Confusion
 

We are going to try to get the weight on the two drive wheels in the back. It is a 18"x6" flat surface. Any mounting would happen off of two 18" bars of 80/20.

Re: Ballast Confusion
 

18 x 6 = 108 square inches. Steel weighs .283 lbs per cubic inch. You'd need 106 cubic inches of steel to get 30 lbs. That's about an inch thick, covering that rear area!

Cast iron sports weights are about that thick, if you got three of the 10 lb weights they might fit back there...maybe...

Re: Ballast Confusion
 

If you used tubular construction, you can drill a hole in a tube and pour in some lead shot. Cheap, effective, and it doesn't change the look of your robot any.

Re: Ballast Confusion
 

isn't Lead considered poisonous, much like Mercury and Radon, being the reason that FRC teams can't use lead solder at FIRST events?

Re: Ballast Confusion
 

Vaporized lead can be hazardous if you ingest / breathe it, yes. However, I have been unable to find the rule you're talking about regarding not using lead solder at competitions. Can you please cite it?

Also, I would suggest that there are many dangerous chemicals inside both the battery and the control boards (heavy metals, lead, etc). Unless you plan on somehow eating your control components and battery, they are usually benign. Having lead sealed inside your frame would hardly be dangerous - though it might make quite a mess if you managed to fracture your frame :yikes:

Re: Ballast Confusion
 

The weight problem hit our previous year's robot, we used a 14 pound steel plate bolted to the chassis to solve the problem.You could go to your local welding shop and see if they have any scrap steel plate that they want to get rid of.

Re: Ballast Confusion
 

This is true...

it was in the safety quiz (a question about using lead free solder, and i got it wrong)
also John Antilla mentioned that it after he said we had a electronic heat gun..

but i don't know the rule in question

Re: Ballast Confusion
 

You are correct, steel shot is also an option.

397 does use lead to weight our robot for testing. We have several large blocks of it (let me tell you, DONT pick up two brick sized chunks of lead) We just make sure we wash our hands after it. One option is to open up one of the Bimba tanks and fill it with the lead shot then mount that. Frankly, if you break one of those you have bigger problems to worry about.

Whatever you do, keep your weight low and centered over your driven wheels.

Re: Ballast Confusion
 

If you do use lead, please don't machine it while in the pits.

Russ

Methods of adding ballast to underweight robots
 

I have seen numerous threads briefly mentioning ballast or adding weight, buy none really got in depth. So i thought it would be helpful to start a thread completely devoted to adding weight. All ideas are welcome even those of questionable legality.;)

Re: Serious Ballast discussion
 

I'll start it off.

Zip tying weights to the frame or adding armor to your bot.
Armor would be sweet.:D

Re: Serious Ballast discussion
 

Might I suggest reading http://www.chiefdelphi.com/forums/sh...threadid=73430 ?

Yes, that is a serious discussion.

Re: Serious Ballast discussion
 

We've toyed with putting a copy of the McMaster-Carr catalog next to the battery, or adding a coffee maker. (The jous of being underweight ...)

Re: Methods of adding ballast to underweight robots
 

These threads are now merged. All further discussion can continue here.

Re: Methods of adding ballast to underweight robots
 

Steel sheet or plate under the chassis is a very good (perhaps best) method of weighting a robot, because it keeps the center of gravity (CG) as low as possible. Because the regolith is so slick, tipping robots should not be a problem this year, but if your CG is above the crater rail you could tip your robot over by slamming into the side rail (and it would not be recoverable as it would then be outside the crater).

Re: Methods of adding ballast to underweight robots
 

Steel plate is good, although not very dense. Lead is good as it's more dense than iron, but I would use gold -- it's 72% denser than lead and it would make your robot shiny. :)

Re: Methods of adding ballast to underweight robots
 

ADD more wheels, more wheels seemed to help in our tests. But thatz us, wheels are about a pound with bearings (overestimate).

Re: Methods of adding ballast to underweight robots
 

Last year we used a bunch of the old short bolts and star nuts from previous years' kitbot frames. We filled up two NoS energy-drink bottles and attached them to the robot. I can't tell you how many questions I got about those bottles last year...

Re: Methods of adding ballast to underweight robots
 

If you have to add weight with the poor cof of the wheels it would be best to ballance ths weight distubution so all the wheels see the same weight staticaly.

Re: Methods of adding ballast to underweight robots
 

I bet that there will be no shortage of FRC teams willing to donate their bots' extra weight to yours after their initial weighin.

Re: Methods of adding ballast to underweight robots
 

Nonfunctional decorations!

A few cold cathode tubes . . .
30 pounds worth of blinking LEDs . . .



Or you could add 30 pounds worth of sensors and related wiring to better control your robot.

Re: Methods of adding ballast to underweight robots
 

Indeed, for robots with power to all wheels, there is no need to emphasize weight over any particular wheels. Unfortunately, it appears that some teams will field robots with only some wheels powered, so it's important for those teams to put the weight over the powered wheels (within reason to prevent tipping, of course).

Re: Methods of adding ballast to underweight robots
 

That would be amazing. I can picture it now...:D

Re: Methods of adding ballast to underweight robots
 

I was actually thinking of using a second battery to add more weight if we are under. The rules say we can't use more than two. Technically speaking only one would be hooked up at a time. That way between matches we just hook to the opposite battery that is strapped on. This way we'd always have a charged battery on the robot for those matches that are close to back to this would be benefical

Re: Methods of adding ballast to underweight robots
 

Uh, no they don't!

LAST year's rules allowed two, the main 12V and the smaller backup battery. THIS year's rules do not allow more than one. <R01-A>, <R11-A> first bullet, and more importantly, <R38>.

Re: Methods of adding ballast to underweight robots
 

I think we will go with a system of steel plates that can be transferred from side to side so the weight stays equal on both drive wheels.

Thanks for all the suggestions from all of us at 1245!

Re: Methods of adding ballast to underweight robots
 

If you are using pneumatics, you can put as many cylinders (not to be confused with accumulators) on as you want. If you hook them up to your 60 psi side, you will gain extra air storage while solving your weight issue.

Re: Methods of adding ballast to underweight robots
 

Might I suggest the Tumbleweed weight gain diet?
http://www.chiefdelphi.com/media/photos/31418
I would say its one of the fastest ways to add a few pounds to your bot! :P

Re: Methods of adding ballast to underweight robots
 

Armor would be sweet hehe:cool:

Re: Methods of adding ballast to underweight robots
 

you could add underglow, LEDs/Neon lights, to your robot. :cool:

Armor would be sweet. Or you could take 30 lbs worth of tools and strap them to the robot. Then you'd never have to go back to the pit! :D

Re: Methods of adding ballast to underweight robots
 

Please don't do this. While I don't see anything in the rules to make it explicitly illegal, I consider it closer to the bad side of the "cheating" vs. "clever engineering" scale. The rules do say not to use extra tubing for this purpose, and I'd use that as an indication of the intent of the rules.

Re: Methods of adding ballast to underweight robots
 

Throw in some diamond plate and make the delorean =]

Re: Methods of adding ballast to underweight robots
 

I'd like to start this discussion up again. We are underweight but also have skewed weights over each wheel. I've been thinking of riveting 2 foot long pieces of 1x1 (sealed on one side and removable cap on the other) to each corner "tier" (vertical beam on the bot that essentially form a box) and filling them with steel or lead shot. This way, we can quickly add more or less shot to each beam on thursday to adjust weight with each wheel resting on a cheapo bathroom scale.

Any thoughts?

thanks, Vivek

EDIT: What sort of store would have lead or steel shot locally? I know Mcmaster has it but shipping will be ridiculous.

Re: Methods of adding ballast to underweight robots
 

dimond-plate is obviously the best choice:D

Re: Methods of adding ballast to underweight robots
 

Try a local gun store. They should have lead shot in sacks for use by shotshell reloaders. They will have several different sizes...your choice.
Not cheap but you won't have to ship it..

Re: Methods of adding ballast to underweight robots
 

To err on the safe side, I should have some ideas on alternatives to lead shot.

I just got the idea to use pennies instead. They are cheap and easier to use.

With 2.5 grams per penny, 20 pounds of pennies costs about 36 dollars which isn't too bad.

-Vivek

Re: Methods of adding ballast to underweight robots
 

I think you could use pennies ... They are just about 25% less dense than lead so that's not bad. Better than steel which is something like 30% less than steel
Steel bolts are cheap though...put them or pennies in a PVC pipe...

tungsten is what you really want... but expensive...twice as dense as copper..
pretty cool stuff...

R

Re: Methods of adding ballast to underweight robots
 

Turns out newer (past mid 1980's) pennies are actually 97.5 percent zinc and only have a 2.5 percent copper coating. Who knew?

I think either the pennies or just scrap bolts we have lying around will work. I'll have to take a look at our junk bins later this week.

-vivek

Re: Methods of adding ballast to underweight robots
 

our team used rebar in 2007
it worked great for our purposes

Re: Methods of adding ballast to underweight robots
 

I think it is important at this point to remind everyone, that adding weight needs to be done in a manner that will not cause damage to the field or other robots. For that reason simply using tywraps to hold practice weights or lead blocks in place is not recommended. Use something much more reliable like a threaded fastener. Lead, if used, should be sealed or painted to minimize contamination and as Russ pointed out earlier, should not be machined in the pits.
From the pneumatics even if you don't use the system, the compressor and air tanks as well as actuators can be used as ballast using their normal mounting hardware.
R71> In addition to the items included in the Kit Of Parts, pneumatic system items specifically permitted on 2009 FRC ROBOTS include the following items. All included items must be“off the shelf” pneumatic devices rated by their manufacturers for pressure of at least 125psi, and used in their original, unaltered condition (except as required for assembly with other
components).
A. One or two additional Clippard air storage tanks (Clippard Part Number AVT-32-16), equivalent to those provided in the kit. This means that up to four, and no more, Clippard air storage tanks can be used on the ROBOT.
Lengths of heavy gauge wire can also be used and easily secured with wire ties. #4 or even #0 can be a way to distribute weight easily while increasing the robot weight.
I once had a team mount up a bench vise and another team mounted a toolbox to compensate for the loss of an arm or ramp that they decided was causing more harm than good. Both used heavy, threaded fasteners and of course fell under the COTS parts and cost basis sections of Robot Rules.

Re: Methods of adding ballast to underweight robots
 

Any sporting goods store (and most Walmarts) sell steel BB shots for air rifles. That being said, I'd use pennies as noted by others...

If you go the "shot" route, please be sure that the "removable cap" you use is very secure. In the event that your robot tips over, pounds of "shot" spilling onto the floor will cause a very dangerous situation for referees, field reset, et cetera and will almost certainly get you disqualified...

Regards,

Mike

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.

Re: Methods of adding ballast to underweight robots
 

I know at the midwest regional there was a team filling water bottles with sand. This is a great way to do it because you can evenly distribute the weight across the bot.

Re: Methods of adding ballast to underweight robots
 

At L.A., one of the robots we reinspected for eliminations had made a modification: They'd put diving weights on their robot as ballast. They're in Sacramento this week, probably with said weights still aboard.

Re: Methods of adding ballast to underweight robots
 

Anthony,
Yes, that was the case, but the teams in question had to add additional material to satisfy the lead inspector, namely sealing the bottles with super glue, wrapping entirely with layers of tape and mounting in a very secure manner inside the frame of the robot where they could not be touched by robot collision. Repeated trips to the pit to re-examine the ballast were required as even a small amount of sand would have changed the frictional forces of the floor. In looking back, I am not sure that was the best decision. Although there were no spills, I felt uncomfortable about it the rest of the weekend.

Re: Methods of adding ballast to underweight robots
 

Thank you for that clarification, I knew that they did it, but didn't know how that looked from an inspection standpoint.

Re: Methods of adding ballast to underweight robots
 

For anyone reading this, any modification to the robot after the initial inspection requires a reinspection even if you are removing something. All inspectors would prefer that you contact them prior to making changes especially adding weight. Inspectors have a variety of ideas on specific changes and their impact on your robot and team play. Adding weight of the type described (kitty litter, sand, shot, ball bearings, etc.) should be discussed with the inspector prior to adding them even before your initial inspection. Inspectors need to discuss these things with the FTA and Head Ref as well so there is no surprises when you get on the field. Again a reminder on lead of any kind...it must be sealed (i.e. painted, dipped, etc.) prior to bringing to an event and may not be machined in the arena, i.e. no drilling, cutting, filing or breaking.

Re: Methods of adding ballast to underweight robots
 

The route we have went this year was by using 3/4" threaded rod with large washers on it, then just fine tuning the number of washers. They are solidly bolted down and cant really make a mess so it works well.

Re: Methods of adding ballast to underweight robots
 

My recollection is that another rookie team with drive chassis, barbell weights, and a small scoop+kicker wheel got the judges award;

The Kit Tub bot rookie team was #3 alliance leader.

Re: Methods of adding ballast to underweight robots
 

You are correct! I got the teams mixed in my head.... the team with the cat litter box took highest rookie seed!