Direct Drive Four Motor System

[sanddrag]

Originally Posted by Matt Adams

Fighting Words: It comes down to a mater of weight, and I think that if you're smart about your chain size (#25) and sprocket materials (aluminum) you'd be hard pressed to say the weight difference is enough to over come the disadvantages. I don't considering creating a good chain tensioning system upfront and spending a few minutes to tighten it every few matches at the first regional to be terribly inconvenient vs. the tolerances and assembly requirements of building 4 robust gearboxes.

Just some thoughts and fighting words,

Matt

And there you have it. Over the years, I have seen SO MANY chain drives that are WAY oversized (we used to be guilty of this charge as well). There are certainly reasons to use larger chain and/or larger spockets, but try to imagine it being smaller/lighter, and then put forward some effort into making that happen.

This past year on our 6 motor drive robot with the very grippy "McMaster tread" and we used #25 (1/4 pitch) chain and tiny 13 tooth sprockets to link the wheels. Only broke one chain (of four on the machine) once ever and that was due to a very rare circumstance. If we can do #25 with six motors, you can definitely do it with four.

All we had to do was develop a good way to get and keep the sprockets inline, and develop a good tensioning system and we were virtually trouble free from then on out.

There is no good reason to link together your wheels with huge and heavy sprockets. We had the most powerful drive setup you can have, and we had pretty much the most grippy tread you can have and we had the smallest sprockets of anyone, and it worked! And it is no stroke of luck. Small chain, and small sprockets, CAN work for you too.

For all of you stuck in the world of #35, please, step into the future. A future full of wonderful weight savings.

If you aren't using #25 chain in your drive system, either it is an 8 motor drive system, or has 16" wheels, or you are doing something wrong. At least just try it and I think you'll be surprised. #25 chain is wonderful.

[Tristan Lall]

Originally Posted by sanddrag

If you aren't using #25 chain in your drive system, either it is an 8 motor drive system, or has 16" wheels, or you are doing something wrong. At least just try it and I think you'll be surprised. #25 chain is wonderful.

Guilty as charged; 6 motors with 8" wheels, and relatively small sprockets (for reduction purposes) breaks #25 chain. 6 motors with 4" wheels, and 1:1 sprockets doesn't, because the stress in the chain is considerably less. (Speaking in general terms, for both cases, with the math and experience to back it up!)

Now, if you want to consider the 8" wheels a bad design choice, that's probably fair enough—but it doesn't necessarily mean that there's anything wrong with the chain installation itself, even if it breaks #25.

[Holtzman]

Excuse the off-topic nature of this post, but I feel it needs to be said… again

Sanddrag

You take every possible opportunity to plug your own drive train. I know I speak for many members of the CD community when I say we are getting a little tired of hearing about it. You built a 6 motor shifter… congratulations. Your design was elegant and very robust, but adding an extra motor in your drive train doesn’t make your robot all-powerful. Try to set an example for the students reading CD and stop bragging about your own drive train.

[KenWittlief]

its a little early in the year to be deciding or debating which drive train configuration is the best

seeing how the game itself wont be announced until early NEXT YEAR! (january :^)

every year presents new challenges. What worked well last year might well be a clunker-bot this year

keep an open mind!

[dlavery]

Originally Posted by KenWittlief

every year presents new challenges. What worked well last year might well be a clunker-bot this year
keep an open mind!

Wise words from Ken.

[sanddrag]

Originally Posted by Holtzman

Excuse the off-topic nature of this post, but I feel it needs to be said… again

Sanddrag

You take every possible opportunity to plug your own drive train. I know I speak for many members of the CD community when I say we are getting a little tired of hearing about it. You built a 6 motor shifter… congratulations. Your design was elegant and very robust, but adding an extra motor in your drive train doesn’t make your robot all-powerful. Try to set an example for the students reading CD and stop bragging about your own drive train.

Things like this I don't just "excuse." Maybe you should "set an example for the students reading CD" and not publicly call someone out as you have in your above post.

But since we've already crossed that threshold, why stop now. (hold on to your seat belts ladies and gentlemen. )

I have every right to plug my own team's drivetrain any chance I get. Just as you have every right to ignore all my "bragging" about the HexaMax.

And actually adding another two motors in the drivetrain does make the robot all-powerful. I am unaware of any robot as powerful as this one this past year.

I try to set an example by sharing my knowledge and expertise with unique systems like the HexaMax. There are teams who would have never attempted building a shifting transmission until they saw ours, and I showed them how it works. So, THAT is how I set an example, not by bragging. I don't come on here for my afternoon cheap thrills; I come on here to help people, and to inspire people, and occassionally get the reverse for myself. If my methods haven't worked for you, I'm quite sorry.

Do you know how many people don't even know that FIRST offers scholarships? Probably a similar number of people don't know that they ARE capable of building something really cool like a shifting transmission. The more exposure to it they get, the more comfortable with it they will become. It is all about exposure. In my mentions of the HexaMax, I intend not to flaunt it as the greatest drive system ever in FIRST. Clearly it is not. I use it to "raise the bar" for all the other teams. Why did we build a 6 motor drive? Because we knew no one else would. Simple as that. Now it has been done, and it has been refined. So maybe next year, there will be multiple teams that do so. I now leave it up to other teams to take it above and beyond. A six motor shifting crab drive, a six motor 3 speed, a six motor shifting walking robot, a 6 motor drive that weighs 12lbs, heck, I don't know. But I believe my design inspires others to strive for more (as we had) in their future designs.

Now, as for the credibility of Holtzman's post, I remind you that it comes from someone that chose to buy a gearbox instead of building one. Not that their's anything wrong with that; it is a quite strategic decision. However, it does make for an interesting conversation point in the sense that I don't think buying a gearbox as opposed to building one provides anything to brag about. This is where our two teams differ. We have a drivetrain that is worthy of bragging about whereas I believe they do not.

[Veselin Kolev]

Originally Posted by sanddrag

Now, as for the credibility of Holtzman's post, I remind you that it comes from someone that chose to buy a gearbox instead of building one. Not that their's anything wrong with that; it is a quite strategic decision. However, it does make for an interesting conversation point in the sense that I don't think buying a gearbox as opposed to building one provides anything to brag about. This is where our two teams differ. We have a drivetrain that is worthy of bragging about whereas I believe they do not.

Sanddrag,
Although your team did pull of an interesting drive train, there are plenty of other teams that have as well. Many even more impressive than yours. I can always post about how wunderbar my drive trains are, and how awesome the teams are I have built them for are. For example, last year's drive train on 1072's robot was seen to push two opposing robots at the same time, in low gear. We had amazing traction and huge torque off 4 CIMS and six skyway wheels rethreaded with wedgetop, and each transmission was 8 pounds flat. Not too many people can pull that off. However, there was a time for discussing this drive train, and I took full advantage by posting pictures and talking about actual performance, not just saying "how good our drive train was" or "it never broke"

When bragging about a drive train, use numerical facts. 8 pounds. High/low speed, minimum pressure it took for shifting, torque it took to slip the wheels, etc. Make your post relevant to the discussion. Also, do not assume that just because you have 6 motors, you can outpush anyone. I have seen teams using 2 drills (a while ago) effectively bully a robot with 4 motors. Or six.

Although I personally find many areas where your drive train could see improvement, I am not here to diss your drive train. It worked fine. I am here, however, to "diss" how you constantly use your one Hexamax drive train example to justify how six motors two speeds is the way to go, and how people that use any other system (like #35 chain) are doing something wrong. This shows to me that you may be a little narrow-minded, not willing to try other things, things you may think are unorthodox. While I have never used #35 chain for drive train, I have used direct gearing to the wheels, and plenty of other things you may think hideous.

As for influencing other teams, you may be giving teams a false impression of your drive train by always bragging about it. True, you have the right to. But should you? Not everyone else brags about their drive trains, I don't. Because I know that my drive trains are only good for a very select few teams, and they will make their own decisions about what to make. You don't need to always tell people how good your drive train is. For the people that saw it in action, let THEM chose if it worked well or not. And let THEM decide if they want to base their designs on yours. Pounding it into our heads isn't going to help is, it may mislead us.

We aren't trying to compete for who's drive train is copied by rookie teams the most. It is a bad idea to think your drive train is so good it can apply to anyone. As you see, the kit drive train is very generalized, and was made by engineers to serve the purpose of a drive train anyone can use. I do not think "sanddrag's hexamax" can be compared to the kit, nor can it be advertised like the kit. Your drive train worked well for you. It would not work well for anyone who tried it. The kit was designed to work well for anyone. I can always say my swerve drive from my sophomore year in high school was good. But I think it sucked, it was a terrible design and I made a million improvements during the past few years. It would be a disaster for some teams to try it.

My point is, we can do other people on Chiefdelphi forums some courtesy and DISCUSS our drive trains, not brag about them. We can not post things we have posted in dozens of other threads. We can at least admit to ourselves that our own designs arent perfect, simply because we can always improve on them. We can humble ourselves and not think we have made the ultimate, full proof drive train. Because remember, we may be wrong about some of the things we say here on Chiefdelphi. #25 chain has been known to break, 2 speed transmissions are not always so great, and 6 motor 2 speed gearboxes are not so impressive when they weigh 12 pounds, because they have been known to weigh 8. Just look at my drive train for team 100. You don't see me bragging about how amazing my six motor drive is, do you? Anyway... we should all just be humble, courteous, and act like gentlemen (or ladies) on these forums, and not fill it with yakking about who's drive train is better. My two cents.

[Karthik]

Originally Posted by sanddrag

Now, as for the credibility of Holtzman's post, I remind you that it comes from someone that chose to buy a gearbox instead of building one. Not that their's anything wrong with that; it is a quite strategic decision. However, it does make for an interesting conversation point in the sense that I don't think buying a gearbox as opposed to building one provides anything to brag about. This is where our two teams differ. We have a drivetrain that is worthy of bragging about whereas I believe they do not.

Sanddrag,

First off, Tyler has never bragged about our drivetrain. He's a young man, who knows much about respect and humility. He would never would come here and make arrogant boasts about the drivetrain he helped design. That's not the way he, or our team operates.

As to your comments that our drivetrain isn't worthy about bragging about because the gearboxes were purchased, that is true we did buy AM shifters. This does not mean there wasn't any original engineering in our system. Your comment demeans all the hard work put into our design by our students and mentors. I don't believe that bragging on CD is in good taste, nor am I that desperate for attention to do so. But I do take pride in my team's design and work, as we all should be.

I urge everyone to be proud of their own designs. We all should take ownership of our work. I also urge people to share their designs, in hopes of inspiring other as Sanddrag mentioned. That being said, there is a line between sharing/explaining a design and repeatedly glorifying one's design in a self-admiring way. Let the design speak for itself. There's no need to shove it down anyone's throat. Follow the examples of people like JVN and Ian Mackenzie. These guys have designed amazing drive systems, and made the designs available to all. Do they come on CD and plug their design everyday? No of course not. Why? Because they're above that. Their egos don't need constant stroking, so they have no reason to resort to bragging.

Humility tends to take people places, pompous boasts tend to get people left at home by themselves.

[Tristan Lall]

Originally Posted by sanddrag

Now, as for the credibility of Holtzman's post, I remind you that it comes from someone that chose to buy a gearbox instead of building one. Not that their's anything wrong with that; it is a quite strategic decision. However, it does make for an interesting conversation point in the sense that I don't think buying a gearbox as opposed to building one provides anything to brag about. This is where our two teams differ. We have a drivetrain that is worthy of bragging about whereas I believe they do not.

I'd really like to point out that this isn't a very credible way of arguing the point. After all, are we saying that ChiefDelphi had nothing to brag about when they first stuffed their robot full of DeWalts?

More to the point, Simbotics in 2003 and 2004 definitely had something to brag about, using those criteria—but should the fact that the rest of their 2005 drivetrain was innovative, succesful, and built and designed by the team be overshadowed by the fact that they bought AndyMark's products?

Sometimes, you have to defer to the convenience of the prebuilt system, and sometimes you need to do it yourself, in order to get the job done. You can't, however, categorically state that all prebuilt gearboxes are less notable than the team-built ones, after all, it's not hard be proud of an off-the-shelf part that works well, as opposed to a custom part which doesn't.

[KenWittlief]

actually, engineers prefer to use off-the-shelf components

if you have to redesign the wheel (or the transmission/gearbox) to make your robot come together, you have not done as good a job, as someone else who is able to put together an effective robot with off the shelf components.

from every perspective, custom designs are expensive

another 2¢ from Ken :^)

[sanddrag]

Originally Posted by KenWittlief

actually, engineers prefer to use off-the-shelf components

if you have to redesign the wheel (or the transmission/gearbox) to make your robot come together, you have not done as good a job, as someone else who is able to put together an effective robot with off the shelf components.

from every perspective, custom designs are expensive

another 2¢ from Ken :^)

A Ferrari is very expensive, but a gokart works almost as well, so I'll just buy that instead?

And as for redesigning the wheel, I direct you here

We did better than off the shelf. Did we have to? No. But we wanted to and that's what makes us different.

[JVN]

Originally Posted by sanddrag

A Ferrari is very expensive, but a gokart works almost as well, so I'll just buy that instead?

If you're on a go-kart track. YES!

I have no problem with people pimping their designs. I know that when someone asks me for help on a gearbox, the first thing I do is send some examples to talk around; and yes, they are examples of my own design.

Where I have a problem, is when people repeatedly disparage those teams that designed simple systems, with the goal of elegant completion of the design challenge. You keep badmouthing teams that didn't design something like your system. Look, I'm sorry 229 didn't build a 6 motor shifter. We've had the design since pre-season 2004, but... WE DIDNT NEED IT FOR THE GAME!

This is terribly off-topic; and I appologize.
I suggest everyone gets back to helping Collin.

-JV

[Cory]

Originally Posted by sanddrag

Now, as for the credibility of Holtzman's post, I remind you that it comes from someone that chose to buy a gearbox instead of building one. Not that their's anything wrong with that; it is a quite strategic decision. However, it does make for an interesting conversation point in the sense that I don't think buying a gearbox as opposed to building one provides anything to brag about. This is where our two teams differ. We have a drivetrain that is worthy of bragging about whereas I believe they do not.

I think it makes them pretty credible.

After all, they were smarter than you. They paid $300 for something that accomplished the game goals just as effective as yours ever could have, seeing as pushing power was never needed, whereas you spent six weeks designing and building a drivetrain that's living in 2002.

While you were off adding extra motors, they were busy building one badass robot.

[JVN]

Originally Posted by Cory

While you were off adding extra motors, they were busy building one badass robot.

Actually, they built four.

[Tristan Lall]

Originally Posted by JVN

Actually, they built four.

+1 if you count the prototype drive base.