Our team was thinking about putting our electrical components in a plexiglass box, the only problem we are having so far is that we don’t know what adhesives we could use to put them together, could you help us find the best one to use. I thank you many times in advance.
P.S. Sorry if this is in the wrong board
First of all, don’t use plexiglass. It fractures easily, and not permitted on the robot. We use MEK (methyl ethyl ketone) as a solvent glue for Lexan (ploycarbonate plastic). If the part is under stress, we sometimes use machine screws tapped into the joints for extra strength, along with glueing. For a good glue joint, ensure the surfaces are clean and flat, and clamp until the solvent has evaporated, and the joint has solidified. Hope that helps. 
Ooh, an electronics box, neat. Our team put all of our electronics in a box last year too: http://www.chiefdelphi.com/media/photos/26295
It looked really awesome because everything was all tight and compact in a removable box, but changing things became very difficult because we had to take the whole box out of the robot to fix or change anything. Don’t forget to mount the RC so the lights are visible…we mounted the front towards one of the outside faces of our box using standoffs, so you could see it pretty well, but when you wanted to add any PWM cables, you had to unscrew the RC.
Post pictures when you’re done!
While I agree with the recommendation to use Lexan over Plexiglass, I am not aware of anything in the rules that would prohibit a team from using Plexiglass if they choose to do so.
Jason
And please be careful using this glue! Read the labels and take ALL of the Safety Precautions. Get the MSDS and really read this one!
I’ve definitely been considering Lexan over plexiglass the way it is talked about, and right now it looks life we may be using silicon to put it together and then bending the lexan (maybe). Also there will be two boxes one for the controller at the front of the robot, and then one with everything else at the back.
But i will definitely take what y’all have said into consideration, and will post pics whenever we our done.
superglue works fine( Cyanoacrylate). correct me if im wrong or this is unsafe please.
thanks, vivek
The folks who sell you the plastic can sell you the glue. Basically it is a solvent that melts the plastic.
Cyanoacrylate is OK, but test first on some scraps - certain plastics will craze (spiderweb of fine cracks) from it and lose all strength.
As long as the box does not carry any load, silicone sealer will be fine, BUT remember it really is not that strong.
If you do use MEK, be real careful, especially with the rule “use in a well0ventilated area”, that stuff is nasty and breathing it is contraindicated by your operations manual…
Don
Originally Posted by Teched3
…don’t use plexiglass. It fractures easily, and not permitted on the robot…
Need to see the rule number, please. I cannot find it in any FRC document.
Is it just a local “team rule”???
You can cause a lot of confusion by quoting rules that don’t exist.
In years past, plexiglass (acryllic) was specifically forbidden. I do not no if this is still the case, but I can not encourage you strongly enough to avoid plexiglass. It shatters under impact!. Lexan (polycarbonate) is impact resistant.
In either case, the joint will be strongest if you have clean straight edges. Consider a pass over a belt sander with fine grit paper to knock down any high spots. (CNC machining would be best, but most of us don’t have that luxury.)
Best of luck. (Use Lexan!)
Lee
Mentor - Team 2108
How long ago was that? It wasn’t forbidden when I was in FIRST and that’s going back four years.
I can not find any rule that said we can not use plexiglass. If anyone knows that this is a real rule let me know. We are a rookie team and would have used lexan if we had to do it again but we already have our electrical board together on plexiglass and have been succesful in drilling and cutting it.
Plexiglass may not be specifically forbidden however it is a very good idea to see if you can replace it with lexan. Even a thin sheet of lexan would be safer for your electronics and its worth the $30-40 to buy a sheet of lexan over the $450 for a new RC or $120 for a new Victor.
we use polycarbonate and we use Velcro to stick down components. with the really sticky Velcro a little bit goes a long way, and you can peel up a damaged component and stick down a new one very quickly. we also usually have an access door or a side that comes off that is either hinged with some sort of lock, or an entire side comes off when you un-do some socket-head cap-screws.
As far as my memory goes, plexiglass (acrylic) is not and has not been forbidden. In 2005, 330 used a sheet for one of their side armor pieces. It took a hit from a robot–that had traveled up the rather steep defensive wedge/outrigger on that side, mind you–and shattered into several large pieces. We replaced it with Lexan and had no further incidents of that sort.
I guess I’ve been around this Cmpetition for too many years, and couldn’t tell you when FIRST stopped specifically banning Plexiglass. I guess it may have happened when they limited us to the amount of certain materials, figuring the robot weight was self-limiting. However, as pointed out by several others, it is a useable material and NOT specifically prohibited by any rule this year that I can find. However, Lexan (polycarbonate) is far superior, easier to machine and work, and definitely safer in the heat of battle. It is the only choice as far as our robot is concerned where this type of material is appropriate. We have made wheels, transmission plates, and component mounts with it over the years. In addition, you can be sure that the plastic on the playing field is polycarbonate and NOT plexiglass, and for good reason:) .
I think you guys may be recalling the effects of an implicit ban. I do not believe that there was even an explicit ban on acrylic. However, there were several years where the non-KitOfParts items were severely constrained, and additional materials were restricted to only those available from Small Parts, Inc. and a very particular list of “approved additional materials.” We were allowed to use “one (1) 4 foot by 4 foot sheet of 1/4-inch polycarbonate.” No other polymer-based plastics were permitted. So the rules effectively prevented the use of acrylic, without ever specifically saying that it was a “banned” material.
-dave
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