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Originally Posted by Greg Perkins
Well, i thank you all for the answers..
but i am an avid battlecombat robot builder, and carbon fibre is an excellent material. its light, and strong. and despite what you guys say, its easy to machine with a simple jigsaw, or a badsaw. i know, i worked with it on many robots. it is also reasonably priced.
I had proposed the idea of making "god plate" which is pretty much the place where everything is mounted...it would go along nicely with the flow of the robot.
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Depending on the resin, you can get away with a bandsaw for some cutting with the proper blade choice, especially if you're willing to put up with a few splinters. I tend to use high temp resins that are little more finicky when it comes to machining. We can also scrap a $1M part for a few splinters in the wrong place
, a problem which you may not worry about quite so much.
Consequently we are pretty picky about how we do our machining.
If you use graphite/epoxy plate stock that comes pre-cured, then there is probably no issue. Cured composites are not generally considered hazardous, it is the uncured resin and particularly the hardeners that are dangerous. You still have the splinter issue, but many stock plates come with a fiberglass outer ply to reduce splintering. A lot of bike parts include this now as well. The glass is practically invisible and it's presence may not be mentioned by the manufacturer or distributor. I know what to look for and have been unable to find it at times, even when I know it is there. So the casual observer can be excused for not noticing it.
A couple of minor concerns to add. Graphite composites are conductive. I wouldn't mount any electronics on them unless you take special precautions to keep things electrically isolated. That includes isolating the scews and bolts holding things down too. Also grapite and aluminum are a galvanic pair. That means that if you get them wet and they are in contact, the aluminum will eat at the graphite. This is a HUGE problem for aircraft that fly off of carriers, but probably not too big a deal for a FIRST robot, unless you have your shop/ storage area 50 yds from the beach in an un-heated building like we do. This can be prevented by ensuring that the fiber and the aluminum never come in contact, another reason for a glass outer ply.
From your original question I thought you were intending to do you own layup. While this can be done with materials that have been legal previously, like epoxy resin, the new rule against using hazardous materials is unclear as to just what level of hazard is acceptable. Everything is hazardous under the right conditions.
Again I might just be a little paranoid here. After all the hazardous materials list where I work includes such items as nitrogen (70% of what you are breathing but too much is deadly), sodium chloride (if you eat too much you can get sick), corn oil (they use it in food, I don't know why it's on the list), Aluminum (as a powder it is a hazard and they wouldn't let me use it!) and my personal favorite, de-ionized water (if you breathe too much it is bad for you).
