Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Max, you must hate Beatty, then. Each of their 4 national championship robots have used PVC in an integral way, along with their custom machined metal parts.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Though I have not had the pleasure of seeing one of 71's robots, from the pictures I have seen, I have great respect for their designs. They exhibit the kind of engineering efficiency few other teams have.

I am not entirely opposed to using any particular material, I'm just pointing out commonly misused materials.

Of course, as I have stated in several threads, material choice is more than simply the best performance for your weight or even for your money but the best performance for your money, weight, and time. You may find a piece of PVC that happens to have a very efficient shape and creating a shape out of a better material with the better efficiency would take too much time or money. I'm only concerned with what I would consider blatant errors like an entire robot out of Lexan.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

We made an all Lean chassis on Team 49 back in 2001.

http://www.chiefdelphi.com/forums/pi...&quiet=Verbose

We had some problems with a lack of rigidity.

Matt B

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Max, please be more careful with your choice of words. It's not the materials that you use, but how you use them that matters. As others have mentioned, you need to be aware of your specific needs and of the strengths and weaknesses of any material you might use. Once all of these considerations have been made, then you can choose the best material for your situation.

To say categorically that making a robot from lexan is a blatant error makes you sound narrow-minded at best and ignorant at worst. SPAM's 1999 and 2000 robots were nearly entirely made from lexan and no one who saw them or played against them would doubt their ability or robustness. Also, SPAM used lexan for vital structural pieces on their 2001, 2002, and 2003 robots with complete success.

I'm sure, as with any other material, there are many teams who have use it successfully and many who have not. I'd say it's similar to how some people refuse to use wood on their robots, yet teams like 173 and 61 use it masterfully. Know your material, know your purpose, and you won't go wrong.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Since this thread has turned to a choice of materials discussion, I would like to point out that in the past 3 years I have noticed a increase in rough play in the game. In 2004 we took several high impact hits. We fortunately survived them with no damage. I would suggest that all teams look at the materials and design with the goal of surviving high speed point impacts. More and more teams are using multiple motor trans and the power and speed is increasing. Plan for it or you'll find you self in the pits making emergency repairs. What worked in the past may not work as well for 2005.
First has opened up the allowed materials. Evaluate the choices and use them.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Seems like people on CD are just out looking for something to be offended by. If there is anyone here who can't find significant design errors on every single robot in FIRST, they obviously don't know much about engineering or building robots.

Additionally, I didn't say categorically that the use of a material is bad, just that certain materials are commonly used incorrectly.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Care to point out a design error in Team 60 and 71's robots in 2002?

And those were just the two that first jumped to mind.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

You know the argument is getting a bit ridiculous when people start using very obscure questions as points...

Nevertheless, if you insist, I will try. I have never seen either of those robots. If you can provide me with a couple of good quality pictures, I might be able to give you an answer.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

I found a couple pictures, don't know if its what you are looking for.
Team 60 - http://www.firstrobotics.net/02galle.../060-1_jpg.htm
Team 71 - http://www.firstrobotics.net/02galle.../071-1_jpg.htm

Try searching soap108.com for videos, I think they have some.

I tend to agree that there will be a few flaws here and there in all bots, but I don't think FIRST meant us to build a perfect bot. Every bot is built to do a certain thing and accomplish a certain aspect of a game.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Another good example of using plastic as a constructive material is 1999 TKO robot from 45.

Polycarbonate, in this case, was an excellent material choice. It was better than steel or aluminum. Anyone want to guess why?

Andy B.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Because it's not too good an idea to have all the weight steel or aluminum would bring, 8 feet up in the air?

And Max, I didn't think it was an obscure question at all. Those two robots are widely acclaimed as among the best ever built by FIRST teams, and all who saw them in action would probably agree that they dont have any significant design flaws.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

It is clear and wouldn't block the drivers view?

In 99, when the playing field was only 24' x 24' I don't know how much more you would be able to see, but that's my guess as I am sure an arm made of aluminum or steel could be equally strong for the same weight.

The only other benefit I can think of is thermal and electrical conductivity (or lack thereof.)

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Well if I remember correctly--
The tkats used that mean arm as a "stiffarm" to prevent teams from getting onto the puck. Perhaps they wanted a "flexy" arm that would give a little bit when it was under "stress". This would protect their gearboxes from damage.

Best guess...

John

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

mmm, yes, good call.

Re: Has any team or anybody made a 80% - 100% lexan bot?
 

Please define "design errors".

If a particular design meets requirements, then by the definition most professionals use, it is correct. If it doesn't meet requirements then it is not. Requirements should NOT be general, like "it won't break". They need to be specific as in "won't break when subjected to a load of 100N in a particular direction". The more numbers the better.

We generally develop a list of requirements for our robot each year. It will include things like "move across the field at 7 ft/s" or "lift 45 lbs of boxes to a height of 3ft in 3 seconds or less". If it meets the requirements (including cost, weight, and time to fabricate) then it is a CORRECT design. That isn't to say it is the BEST design. There will always be room for improvement, but you can spend your life analyzing to get the best result only to find when you look up that it is now next year and there is a new game.

We tell our students "In this game, if you meet your requirements, you win. BEFORE you ever take the field." After that everything else is gravy. (BTW you will win on the field a fair amount of the time as well if you have set your requirements correctly)

We started doing this systematically in 1999. I can't think of a robot since then that hasn't been a "winner", though some have done better in competition than others.

In saying that every FIRST robot has significant "design errors" (whatever they are by your definition) you are impugning the skills of a fair number of technical people who do this sort of thing for a living. Kind of like an apprentice telling a master he's doing it wrong. So don't be too upset if people take offense because, quite frankly, you have just been offensive.

But you're young and foolish (all of 17 is it?) so we won't hold it against you.

ChrisH