Will plexi-glass work?

[MathewSmith]

so anyway, my team gets this great idea to make our robot's frame completely out of plexiglass. With only little metal brackets. I do not think this will work. We are an am. team, and we have nothing done. We have a few small pieces of plexiglass and a few metal brackets. we have no wiring done, no drivetrain. A flawed design that basically will only move. Sooo.....my question is.....Can we basically bend over and kiss our chances of even getting this done goodbye? Any help would be appreciated! thanks

Mathew Smith
team 1352

[Tom Bottiglieri]

plexi glass is heavy!! not only that, but in the competetion (guessing you've never been to one) there is ALOT of pushing a shoving and ramming into each other. If there was no support behind the plexi (like studs in a wall) it would most likely break. I dont know about you, but i wouldnt want to have to fix plexi in the pits. If you are really looking for an easy way out, try getting some reliable wood, or just using the frame they give.

[Yan Wang]

Originally Posted by MathewSmith

so anyway, my team gets this great idea to make our robot's frame completely out of plexiglass. With only little metal brackets. I do not think this will work. We are an am. team, and we have nothing done. We have a few small pieces of plexiglass and a few metal brackets. we have no wiring done, no drivetrain. A flawed design that basically will only move. Sooo.....my question is.....Can we basically bend over and kiss our chances of even getting this done goodbye? Any help would be appreciated! thanks

Mathew Smith
team 1352

This is not supposed to be mean, but, you have NO chance of surviving a match with plexiglass. It will crack and break and splinter into a million pieces when another robot just barely nudges it... Our team learned this the first match in 2001 @ NYC. Hence why we have lots of lexan on reserve now. Attached is a pic of the shattering (the other robot barely nudged us on the side)...

[KyleGilbert45]

I'll throw this link in here so this thread doesn't turn out to be bad.

Critical and picky - here I go again

Even though i've not had much experience using Plexi-glass in robot operations, I've played with it enough to know that it will shatter and crack fairly easily. I also seem to remember a lot of threads in the past asking this exact same question, "Should we use plexi-glass or lexan" and the majority of the time most responses went, "Use lexan" for one reason or another.

Also, one thing i saw was people confusing the terms lexan(polycarbonate) and plexi-glass(acrylic). I just don't want this thread to turn into a "Let's argue about what its called thread".

This is not the end of the world for your robot. With the right support I think it will be just fine, but that's just my opinion.

[Al Skierkiewicz]

Plexiglass is a tough thing to use for robot body. It does shatter and easily cracks when you drill into it. Lexan works better and is less prone to damage but weighs a ton, heavier than aluminum. No you are not out of the competition at this point. Just think about a little modification. Use some aluminum extrusion to frame out the same dimensions you already have and start bolting it together. Move things bit by bit over to the new frame and voila! a robot is born. If you can't get it done before ship, cut as much as you can now and ship all the parts in the container with the robot. You will have lot's of work at your first regional but you can get it done. Ask for help from other teams, they are required to help if they can. I know that one team at Great Lakes last year, came with a box of parts and built their robot at the regional. "Never give up, never surrender!!"

[Andy Baker]

Originally Posted by Yan Wang

This is not supposed to be mean, but, you have NO chance of surviving a match with plexiglass. It will crack and break and splinter into a million pieces when another robot just barely nudges it... Our team learned this the first match in 2001 @ NYC. Hence why we have lots of lexan on reserve now. Attached is a pic of the shattering (the other robot barely nudged us on the side)...

Good advice. One of the things that many people get confused with is the difference between acrylic and polycarbonate. Plexiglas is the best-known trade name for acrylic and Lexan* is the best-known trade names for polcarbonate.

Many people get these two materials confused. I hope that Mathew is saying plexiglas while his team is really using polycarbonate. Like Yan said, polycarbonate works well for many teams, but acrylic does not.

Mathew - are you sure it's plexiglas and not polycarbonate?

* btw, here is a related piece of trivia: Lexan was the first polycarbonate invented. Dan Fox mistakingly created it in 1963, as he was working at General Electric. GE had the patent on it for 17 years before another company could make it. Now there are other trade names, but Lexan is still the original. (I spent 4 co-op terms working for GE Plastics, making Lexan and Ultem.)

Also... a side note: the density of polycarbonate is 0.043 lb/in^3 while the density of aluminum is 0.098 lb/in^3.

[Adam Y.]

Mathew - are you sure it's plexiglas and not polycarbonate?

I'm sure if they broke any pieces drilling them it probably is polycarbonate. Those materials are a pain in the but to use.

Also, one thing i saw was people confusing the terms lexan(polycarbonate) and plexi-glass(acrylic). I just don't want this thread to turn into a "Let's argue about what its called thread".

Actually they are trade-names which is why it gets so confusing. The trade names for polycarbonate are: Lexan, Hyzod, and Tuffak. The trade names for acrylic well according to my book there is only one trade name. It is plexi-glass. Go figure. Also I have heard bad stories about using loctite on plastic materials. I heard it actually weakens the materials. Anyone care to find out if this is true?
*hint* Want to see something cool. Take two polarizing filters and stack them one on top of the other. Turn them until you can't see any light coming out. Then point them at a opaque material like lexan. You would be able to see any of the stresses put on the material*end of hint*

[KenWittlief]

thsi late in the season I recommed you use 3/8" plywood for the base and the 2x4 alum pieces that FIRST gave your for the sides.

we built a pratice robot like this in november with parts left over from last year. It only took us 3 one hour meetings, at the highschool, to put it together and get it running

Im certain you could do the same in one weekend.

[Gary Dillard]

Sorry to hear about your problems, but don't throw in the towel yet. It's easy to get overwhelmed, especially in your rookie year, with trying to do too much and seeing alot of things fail. You still have over a week left - see what you can do positively. Ken's idea about plywood and kit parts is a good start - get something driving so you can get some practice. A moving robot is an asset in any match - you can certainly block your opponent's corral and you can push balls even if one at a time. Use the default code - go back to square one and take smaller steps.

BTW - when you get to the competition I think you'll be surprised at how supportive other teams are. No-one will look down on you if your robot is dead, in fact they'll pitch in and try to help you get it started. You will enjoy this event regardless of how you robot performs.

Our rookie robot was named "Kenny" because it got killed every match. But we learned alot and moved on.

And don't use plexiglass/acrylic. Use Lexan/polycarbonate.

[Stephen Kowski]

if you go with lexan instead of plexiglass ask for polycarbonate - same stuff much cheaper.....gl

[caffel]

There is only one plastic strong and tough enough. LEXAN.
All, that is All of the other and cheaper choi ces will crack and let you down. I can tell you this after 4 years of experience.

[Ryan Albright]

any chance of using lexa or plexiglass for a base is nto good. I am guess you are a rookie team. We use lexan to protect the compenents of our robot and for skins. Lexan is strong but not made to be a base. I would not quit yet but i would suggest go get some wood like mentioned about and just build it out of wood. Especially with a game that i think is gonna involve alot of contact between robots like last year youa re gonna need somethign that holds up

[Scott England]

Didn't plexiglass(acrylic) used to be illegal on FIRST robots since it is so brittle? I know some acrylic got mixed in with our excess stock of polycarbonate, found out the hard way when it shattered while trying to be bent. Eitherway, polycarbonate frames have been done before. In 2001 we had a robot with no structural metal
Browsing the gallery, it looks like team 49 also did a robot made primarily out of lexan

So yes its possible, given your time crunch though, wood might be easier to get and to work with. Just get a drive train that runs first and go from there, there's still plenty of time left. Good luck,
~Scott

[pras870]

I agree, if you absolutely must use a plastic, use lexan. It is more durable, and while it does splinter and shatter, it is less likely to do besides plexiglass. If you use this, you have to support it, using plexiglass or lexan will no support is a sure way to have a base be totally demolished. Supporting the base with aluminum extursion at stress points (if you can, ask an engineer to evaluate your design and offer advice on where to support it) is a very good idea.

Now Ken is also right. There is absolutely nothing wrong with using plywood as a base. In fact, one team that comes to mind that uses a wood base every year and is one of the well known teams in FIRST is Team 173 Rage. Every year they use a wood frame (which I'm not mistaken is supported by aluminum brackets). It may splinter, but with the brackets, it's an easy fix. Just put a sheet of aluminum or steel over it, bolt it on, and you're ready to go. I bring up Rage, because they are one of the well known teams that uses a wood base, and have so for years.

And yes, if you turn up at your regional with your robot unfinished, it's guarenteed other teams will come over to help you. No team is going to look down upon you, in fact most teams will do everything in their power to make sure your robot works and is able to compete. That's the great thing about FIRST, everyone is willing to help each other to make sure the competition is as good as it can be and everyone has a fighting chance.

[ngreen]

I don't know how physical this years matches will be but last year we shattered the side of a lexan robot in our first practice match (they ran into us). I still have a piece of it.

I would use wood and the aluminum for the kit. You can definitely get something driving and it will cut down on the repairs you will have to do at competition. You can compete if you can make something that can drive every match.