Uses of Lexan
 

My team (5811) has a sponsorer who is a plastics manufacturer; they allow us to have any scrap material we want so we have a stock pile of lexan in our shop. Last season we used it as guide pannels for our intake and decoration. I was wondering if lexan (or other plastics) can be used for more stuctural components in robot build

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Re: Uses of Lexan
 

Lexan or polycarbonate is great stuff.

Check out release videos from past years. I remember Team 16 using polycarbonate in their arm in 2014.
https://www.youtube.com/watch?v=lcsi4zBwIjc
Hard to see, but at 12 seconds one can see their arm is clear.

A number of teams made their arms out of polycarbonate in 2016.
We made our arm supports out of 1/4" polycarbonate.
Its not as stiff as aluminum, but it's tough and bounces back.

Dave

Re: Uses of Lexan
 

We use Lexan for a lot of different parts on our bots. Good stuff. For structural components you need to ensure that they are thick enough or rigid enough for the application, which can add weight.

Re: Uses of Lexan
 

I would recommend looking at and contacting someone from 1714:
http://www.thebluealliance.com/team/1714/2012

They do not have a 2016 picture on Blue alliance, but there are pictures from several other years. They often build a "clear" robot.

FRC 703 also used to build a lot of chassis components out of Polycarbonate.

Lexan or polycarbonate is a wonderful material, and with proper techniques can be an incredibly useful material.

Many teams use the very thins stuff (under 1/16th and sometimes as thin as 0.020") for body panels with graphics. Well applied and designed body panels can make a robot get a new personality and have a much higher appearance of quality. when applied with Velcro, the panels offer easy access for pit crew, but a reasonable deterrent for other robots poking into your bot, or it getting hung up on field elements. The thinner you go, often the less robust.

Other good plastic parts are skids and sliders often made of UHMW or HDPE plastics. These can be good skids and guide for elements that strike field elements.

Re: Uses of Lexan
 

The short version is yes. As IKE said, people from 1714 would be great to contact for more info (my HS team, haven't been in touch with them in awhile, hope y'all are doing great stuff, etc)

The key things to remember are that lexan is strong, but not particularly rigid. As a very rough approximation, to get a piece roughly as strong as an aluminum piece, you'll want to double the thickness (so a 1/4" lexan plate is roughly as strong and vaguely as rigid as a 1/8" aluminum plate). So for more structural pieces on a robot you'll end up using more 1/4" or even 3/8" lexan plate. Things like 1/8" lexan are great for lining surfaces supported by other materials (i.e. to form a flat area between two aluminum tubes, etc). 1/8" lexan can also be used for gussets but they do tend to be a bit weaker, so 1/4" or 3/16" lexan gussets are a safer bet.

The best use for structural lexan is in over-the-bumper manipulator components that deal with impacts from other robots. Things such as intakes, defense manipulators from this year, etc. The elastic deformability of lexan helps absorb the energy from impacts and prevents permanent bending in a mechanism that would otherwise bend if made from thin wall aluminum. Lots of teams used lexan in 2014 ball intakes extensively.

Re: Uses of Lexan
 

Our team built a lexan bender (toaster wire, plywood, wiring and hinges) and were able to make a lot with it. Our intake's guides were bent lexan, our upper electronics board was held up by bent lexan and our bridge that held our camera and shooter sensors was made of bent lexan. Good stuff! If you want to prototype you can use cardboard...

Re: Uses of Lexan
 

We used lexan for the claw of our catapult this year as well as for the guides to slide the portcullis up.

Re: Uses of Lexan
 

Lexan is great. We used it structurally on our intake arm, and later on we used Lexan disks over sprockets to prevent the robot treads from derailing.

Re: Uses of Lexan
 

Lexan has many uses, we used it this year for our electronics boards, the fact that it's clear really helped when having to see inside the robot. We also used it as our sponsor board, easy removal when attached with velcro. Really anything that you want a large surface area but don't mind a little bit of flexibility, lexan will work for, and the transparency is a nice bonus.

Re: Uses of Lexan
 

Polycarbonate is a fantastic material! I like to use it for some gussets, also it can be used a bunch in prototyping. Like other people have said its good for intakes as well. In my experience it's been better to use in prototyping because it's much faster and easier to form and build with then sheet metal.

Re: Uses of Lexan
 

We actually used Lexan to rebuild our shooter deck for worlds this year, it was originally made of 1/8 inch aluminum, then to save weight and make it stronger(more resilient to impact) we made it of Lexan that was CNC milled exactly the same as the Aluminium, worked really well

Re: Uses of Lexan
 

Lucky you! Lexan is wonderful stuff. Strong relative to its mass. Our team has found it very useful for protecting electronics. I'm sure your team will discover all sorts of ways to put it to good use.

Re: Uses of Lexan
 

Yes as others have mentioned, Lexan is good, strong stuff.
All kinds of uses, the thickness depends on your use for it.

The thicker stuff (.375") can be drilled and tapped at the face or edges to take a 10-32 screw (as an example) to fasten to.

.25" can be drilled and tapped on the face.

The 1/16" is great for guards and graphics, we use Velcro for stuff like that so we can take it off when working on the robot.

Re: Uses of Lexan
 

Obligatory reminder to make sure you're using polycarbonate/Lexan/Makrolon and not acrylic/Plexiglas/Lucite. Polycarbonate is probably the second most useful robot building material after aluminum. I consider it to be more versatile because it's easier to machine on the fly (less setup required). There are hundreds of uses for it even if your main robot frame is aluminum.

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1257 uses a lot of Lexan/polycarbonate. In addition to some of the uses others have mentioned, our primary construction method for the past two years has been aluminum tubing with 1/4" polycarbonate gussets.

Re: Uses of Lexan
 

Team 701 generally use lexan for prototyping. We also use it for covers for pieces that do not need to be exposed like the top of our shooter where the gears are.

Re: Uses of Lexan
 

To add to Spencer's comment: The unit is portable (just a few lbs in weight without the battery) and is powered with one of our old 12 volt batteries. We take it to competitions and have assisted other teams needing a straight bend in their lexan. Simple and practical:)

Re: Uses of Lexan
 

Do you happen to have a picture of it or a diagram of it? Your bender sounds like a great addition to any team!

Re: Uses of Lexan
 

We used lexan a lot this year due to a lexan sponsor. A lot of our robot was clear including rails for the portcullis, actuators for the cheval, a belly pan for electronics, and the ball guidance system. I really like it as a material (it looks cool). For bending, we used a heat gun, which I don't recommend, but it was the only way.

Re: Uses of Lexan
 

We had great success using 1/4" & 1/2" lexan for out catapult. Its very easy to work with which allowed us to build our catapult during one of our events with our pit bandsaw.

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I used to use polycarb or lexan as much as possible when making guards for components and other low stress structures. Although it didn't make its way onto 1991's robot, this past year I had made a sturdy scissor lift out of lexan and plastic bolts. I believe the weight of the scissor lift itself was between 1 and 2 lbs. Granted, the entire climbing mechansim was over 5 lbs.
Polycarb and lexan are very strong, and after talking with 4061 (I believe) at worlds, it makes a good amount of sense to use it for arms of an intake or other extending components. Mainly due to the flexibilty of the material, and unlike aluminum it usually goes back to its original shape.

(Just be sure to use lexan or polycarb, and not acrylic. It ends poorly if you try and bend it)

Re: Uses of Lexan
 

We've used polycarbonate in a lot of ways people have already said to good effect, and it's likely the plastic you'll want in main body structural situations (if you want a plastic). But since you're talking about plastics in general, I'll bring up another one: polypropylene.

Polycarb certainly beats polypro in terms of most structural members and loaded applications, but that doesn't mean it's useless beyond paneling. It can take weight with the right shape and volume: you've sat in quite a few polypropylene chairs, and we love to use it for battery boxes in awkward places. It has good toughness and impact strength and is less dense than polycarb--the main limitation is its reduced stiffness. Still, that can make it great for some over-the-bumper end effectors. We used it for our claw an minibot deployer in 2011 (for a regional win as AC2). We rammed the polypro V straight into the minibot pole all season and got the claw bashed up and dragged around with no trouble. Other uses include drivetrain skids (for getting over bumps), game piece ramps (it's slippery), and flexible brackets and guards (nice when you need some flex tolerance). Basically anytime we're about to use polycarb we stop and think 'can it be pro?' since polypro is lighter by volume.

Other novel-ish uses of plastics:
I'm not sure anyone has mentioned pillow blocks, but depending on how your axles are loaded there are a number of plastic options. We've used acetal (polyoxymethylene aka delrin) for end effector blocks before. Really want to analyze and test your loads here, though. We've also used acetal for larger jobs, namely the white skids used to slide up the pyramid in 2013.

Re: Uses of Lexan
 

Not exactly structural, but we used polycarbonate this year as guides for our conveyor (easier to see when zoomed in), which also served to center the ball for the shooter. We used a heat gun to bend the pieces and the distance between them when attached to the robot was slightly smaller than width of the boulder where the guides gripped it, so the ball was slightly compressed while it was being held there. The flexibility of the polycarbonate gave us a firm grip that hugged the ball really nicely. The guides were 1/4" at one point, can't remember if that was the final thickness used or not.

Other uses of polycarb on this year's robot were chain guards, CDF manipulator (linkages on the bottom of the intake), bellypan, sides of our winch spools, and the top of our conveyor (added to block the ball from flying up and out of the robot after being grabbed).

Re: Uses of Lexan
 

In 2010, my older sibling tried to make swerve drive module housing out of Acetal Copolymer Delrin plastic. Unfortunately, it was never used in competition.

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When I saw the thread, my first thought was to MORE Robotics. Incredible team that competes at a very high level every season - and the clear robots they produce are fantastic pieces of engineering!

Re: Uses of Lexan
 

To be fair, there's really no mistaking the two. Polycarbonate is nigh-indestructible and will bend easily, while acrylic tends to crack/shatter if you so much as look at it wrong.

Re: Uses of Lexan
 

Boom!

Thank you everyone for all the ideas and information, it is so helpful.

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Re: Uses of Lexan
 

Photo is posted. Thanks Rob Chapman for the pic and details.

https://www.chiefdelphi.com/media/photos/43953?

Search Youtube for "acrylic bender" and many tutorials come up. Most are 2-3 feet long and are attached to a variable power supply. Since we didn't have a variable power supply, however, the length was determined experimentally using our available DC voltage (12V robot batteries).

It's about 17 inches clip-to-clip.

The 20-gauge nichrome wire was sourced on eBay.

The circuit should be fused for 20 amps.

The one we made was modeled after this one:

https://www.youtube.com/watch?v=XveHMbzbyYQ

Re: Uses of Lexan
 

This is great! Thanks so much for taking the time to post this. I would think this could help out lots of teams.

Re: Uses of Lexan
 

Lexan makes good robot armor! I've seen it used as a "hood" bolted to the top of a robot. It protects most of the robot from damage, and the case of Stronghold, keeps boulders from getting stuck inside of the robot. Because it's clear, it allows you to see inside and tell if there's an issue. I've also seen Lexan panels covering other parts of robots and serving as sponsor plates.

Re: Uses of Lexan
 

237 has used it for a board to mount all the electrical too, sides for protection and other uses in the past. Gearbox covers one year too. It's even good to cut up and machine for prototyping uses too.

I get scraps free/donated (even for my own use) as I work professionally in the robotics and automation field (plastic injection molding) and most guarding is Lexan panels normally in Bosch profile. We go through a lot of it and get leftover scraps regularly.