Re: Fabrication
 

While I don't necessarily have a problem with your answer, before CAD there was Plain Old Drafting. :p

Re: Fabrication
 

Because that's not what happens.

There's a LOT of misconceptions about how the pretty powerhouse robots are created.

The students involved in CAD are typically CADing the drivetrain, while the other students work on designing, manufacturing prototypes, and testing an end effector, which then gets CADed, and all of the parts get manufactured in a professional shop, and then assembled by the students.

They're involved at every step except for manufacturing of the final product. The difference between them and a majority of teams is that a majority of teams are basically fielding their prototype, rather than a finished product.

Re: Fabrication
 

In their first year, I'd suggest that they don' t try to completely CAD out the robot before any tools touch material. It will most likely take too long. As the initial model is being developed, students can be fabricating and testing prototypes, or building components that they know they will be using. As components are finalized, they can begin fabrication - even without a complete CAD model. If nothing else, CAD in parallel with the fabrication.

Make the transition with as little disruption to the way the team works as possible. Most likely, everyone will see the advantages to introducing a bit of design before fabrication begins.

Perhaps watching the Grant Imahara "FIRST Design" video might help.
http://www.youtube.com/watch?v=YNweJ7QbF7Y

- Mr. Van
Coach, Robodox

Re: Fabrication
 

Not true. We drew it. The process was no different, only the tools and medium were different. There was such a thing as design before CAD. Cars, bridges, airplanes, and televisions were not cobbled together by trial and error.

I can see what the OP is saying. I don't see how they didn't have a plan before building. My team loves the fabrication aspect. We do everything in house. They love it so much that no one has any real interest in drawing an entire robot before building. So this year I got stuck drawing portions of the robot in Inventor. Next year I hope to have some students spooled up on the program to draw the robot as we progress.

As for knowing design before fabricating? I think you need to know how to make something before you can really be a great designer. That doesn't mean you need to actually drill a hole but you need to know its possible. It's just more fun to learn by actually doing it.

Re: Fabrication
 

There is really no reason not to CAD. I was our single CADder for our team this year, and I was able to CAD the whole robot before we started building. Again, we had an amazing machine shop, not ridiculous turnarounds, but quicker than we could have done it in. If I had to do it again though, I would recommend CADding a full drive system before the season, preferably 6 wheel, as it is simple, yet robust and maneuverable. We took 2.5 weeks to get a drive CAD out, which was ridiculous. Part of it was that we had a hard time choosing between 6 and 8 wheel, but also, I was just inexperienced(my first year CADding). If they practice, getting a drivetrain CAD done in 2 days can be easily done, and then they will have extra time for manipulators. Furthermore, you will save time by doing this because you don't have to remachine parts.

Re: Fabrication
 

Careful here. Check the timeline rules regarding design and fabrication. If I've got it right (at least for this year and several previous years), you can't take a CAD model you worked on prior to kickoff and use it to fabricate parts without making substantial changes or publishing the files for everyone to use.

- Mr. Van
Coach, Robodox

Re: Fabrication
 

I meant that they CAD the drive system before for practice, and then redo it for the season. Personally, I wen't into the season, and didn't know some things that I should have known. For example, one dilemma I had was deciding wether to use a bearing block, and after that, on a design for a bearing block. Sure, once you have seen Chief Delphi threads on the subject, it is an easy problem to solve, but it is much easier if you already decided on a design path before the season, and are just repeating decisions you made in the preseason, on a drive train that is optimized for the game.

Re: Fabrication
 

Of course we still draw, but not an in-depth kind of drawing. Its more of a "heres my idea", and then the specifics are figured out through prototyping.

This was just my view, I was not taking a shot at successful teams. What they do looks and preforms amazing, so whatever they do works.

I'm not against using cad, we cad things as well. Our 8wd was made in cad before we built it. So was our shooter. But theres no reason the kids can't make them as well, especially if you have a large amount of students that are interested in machining. Teach them how to do it professionally.

Re: Fabrication
 

Regarding this "fabrication is/isn't engineering" business:

We are a team that fabricates entirely in-house (with CAD, though), but most people on the team agree that it's not very sustainable to operate this way -- especially with the short length of the build season. However, an earlier poster noted that the designers may not understand physical limitations as well without manufacturing experience, and I completely agree. This is true even if in-house CNC is in the budget.

The most obvious answer to this, IMO, is to train manufacturing in the off-season primarily where the deadlines are significantly more lax. Students who have that knowledge can then help the designers understand what will and will not work during the actual build season, where out-of-house fab or CNC (i.e., whatever gets the job done best) would be preferred. In addition to a better understanding of the implications of various design choices, I believe this basically satisfies the "moral" issues that some people have with fab-less teams as well.

Our team in particular has yet to implement this. Of course, such a strategy may greatly increase the off-season commitment required (depending on the team, of course), but that's just what it takes to be successful in a competition like FIRST -- hard work and commitment. Regardless of your priorities, training strategies, morals, or whatever else, there isn't a successful team that hasn't worked hard to get where they are, regardless of how they accomplished it.

Re: Fabrication
 

Thank you all for your responses.

I don't mind in house fabrication, in fact, I loved it as a freshman, being able to manufacture my own parts and placing it on the robot. But fabrication without a design is meaningless. This year our mechanical lead student only used L-channel and 80/20 because of the ease of building, and how you can design around the build. When he heard about 1311's robot being fabricated outside and being amazingly done, he said "That's not fun, I like solving problems while building, that's more fun". Fabricating is fun, but fabricating without a design is foolhardy. I think that this attitude needs to be reversed.

Re: Fabrication
 

I completely agree. Yes it is fun to fix problems while building, that is even what our team, and many others did for the minibot. But remind him, that if you do that, it takes up much more time than if a CAD student solved the problem before you machine a part.

Re: Fabrication
 

1768 does very very close to all of our fabrication in house. We have one Bridgeport and one functional lathe, we work hard to make sure that these machines are running all the time. This year we sent out 3 shooter parts to be water jetted, we had never done that before but we didn't see any other reasonable way to make a large cam or to frame out of shooter other than water jetted plates.
Because we need our machines to be running all the time and they are often the rate limiting step in the robot construction process we have started using quite a bit more ABS in our designs, it machines like butter and is incredibly strong.
We have our CAD team working all the time as well and the robot construction doesn't usually pass the CAD until mid way through week 5 or so.
As far as the in house vs sent out argument I think students are going to learn either way, it is just a matter of what they learn and in what areas they excel.

~DK

Re: Fabrication
 

He's almost right. Solving problems while building is not more fun after this competition, however. The real-world version of that (without the boss's response to such a quote if said aloud) follows...

"I like solving problems while building, that's more expensive." And that, my friends, is why you CAD thrice, measure twice, and cut once (and then cut again on any identical parts), and measure again once you're done cutting.

Do a cost add-up. Figure minimum wage for every student, and normal wages for the mentors. Figure out how much the season cost in labor and materials. Now, subtract any material wasted by building something wrong and any time wasted fixing something that was built wrong (and the associated man-hour cost). I think the results might surprise everyone on the team.

There's nothing wrong with building then designing, if you don't mind wasting money and time, and not getting a real-world engineering experience.

Re: Fabrication
 

Its cheaper for us. We don't have the money to send parts out to be made. We do have a pile of scrap metal and nearly infinite wood from our schools wood shop. Its what works for us. This is not meant to be a "Real world engineering experience". This is a robotics competition with teams from high schools made up of high school students that are mentored by real world engineers (be it we don't even have those). Try telling your potential boss "I'd like the job, but you're going to have to hire my mentor as well". In a real world engineering situation, CAD and then sending parts to be made would be the best choice. But this isn't the real world, and not all of us have the luxury of money. There is no right or wrong way to build a robot during build season. It depends on a teams situation what is cheaper. Don't assume everyone is in the same financial boat as you.