Re: How long did it take for you to build your drivetrain?
 

A strategy we're using this year is to incorporate drive train discussions into our trainings with rookies. For example, most people that start to go to trainings have no clue about what’s going on with FIRST robotics, never really read CD, and must be taught everything. That lets us teach them from ground zero, and a little thing we do is give them mock brainstorming sessions, where we "reveal" to them old FIRST games, and they use their knowledge of drive trains (that we gave them) to determine not only the ways a drive train could go about doing the tasks of the game, but which drive train could do it best. In simple words, we let them decide what the best drive train would have been. Of course, as a veteran member, I have to sometimes step in and remind the rookies about our limited money and machining capabilities. It really helps the brainstorming process if you've done it before, but not for real. It's real enough to make a lasting impression on rookies on how to go about making rational decisions during build. And keeping the brainstorming process short.

Anyway, back to the real question. Last year my team did swivel drive, and I was managing that system. The decision process was rather quick, and the design took three days to finalize. Took another three days to distribute parts amongst our two machinists, and then took two weeks to machine. Then... the horrible week of assembly... So in the end it was mounted on our chassis by end of week 5. Well, our school has finals the first week, so we never do anything then. So it took a good 4 weeks to do it all.


The main reason why it took so long to machine and assemble was that it was not an efficient design. It was good and strong, but could have been a lot easier to make. You gotta remember that you can design anything, and build anything, but the building part will always take the most time. It helps to know how to use a mill and lathe so you can design something that is easy to make.

I have a lot to say about this actually... just because there have been too many bad experiences. A few more things that will help cut time: once you finish your design, get accurate quotes for everything you will have to buy. For example, if your design needs four bearings that cost $150 each, don't do it. Redesign your butt off. Also, once you finally do finish the design, order the parts immediately. Who knows how long it will take to ship, and its nice for the machinist to have bearings while he machines the part they go into.

Also, once you finish a design, print out all the parts drawings and give them to a machinist. Don’t worry that the machinist will be discouraged with a big pile of parts to make. They like it when they don’t have to call you and ask if there’s any more. Giving them drawings every few days seems like a good idea, but it just keeps the machinist in the dark and kinda ticked off at you… well at least for me. Anyway… enough blab. Hope that helped.

Re: How long did it take for you to build your drivetrain?
 

Well, maybe what I said sounded a bit too harsh. We hold very lengthy discussions, but we never break into a full fledged arguement, maybe small ones...

Veselin, I wish I could give my drawings to a machinist, but all of our experienced machinists graduated, I'm the only student machinist left. Add to that, we used to do a bunch of machining at the Stanford Linear Accelerator Center, but now after a bunch of problems (we didn't cause them), we're not allowed back in there, which also makes it hard to teach new students how to use machine tools, since we don't have any. We do have access to private machine shops, but we can't go to the shops when ever we choose. Mainly, the majority of the team is concerned about time consumption when it comes to new designs (due to past experiences).

Re: How long did it take for you to build your drivetrain?
 

Team 61's drive train is always done by the second week. We use the same drive train every year.. We make simple easy changes, becuase every year our drive train has been fail proof. In order to aviod problems we do not do any drastic changes unless we have too.

As always check out our website:

http://www.valleytech.k12.ma.us/robotics/

tons of pictures from last year and the past 9 years. You can see how our drive train has not changed as much over this time!! :D

Re: How long did it take for you to build your drivetrain?
 

We don't have the money to do FIRST anymore, but we do BattleBots. Luckily there are lots of companies that make all in one gearbox motor solutions.. so our drive train only takes a little bit of time to get mounted!

I don't recall from the FIRST rules, but if you can use pre-built gearboxes, I do believe someone makes a gearing set for the CIM, all done with alum mounting blocks.