We have traditionally used ½” SandyPly plywood for our electronics boards available from our local Home Depot. It is cheap enough, non-conductive, easy enough to work with and mount electronics to using simple wood screws, but not exactly as light as I would like. I’m looking for a better alternative this year.
I have heard various comments here on CD lately regarding the use of composites, particularly honeycomb fiberglass/aluminum/plastic panels and particularly for use as lightweight but structurally rigid panels for mounting electronics and such. While I have seen these materials on occasional robots at competition I am mostly unfamiliar with these products. For the benefit of us uninitiated in these honeycomb panel products would some of you please provide more information? Particularly, where do you get it? What sizes/thickness do you use? What are the material properties of what you have used in the past such as weight per square foot per thickness? How easy/difficult is it to work with (how do you cut/drill/machine it)? How expensive is it? How do you mount electronics to it (screws?, tape?)? What else have you found it useful for?
We have used Alumalite with good success. It has a plastic core with aluminum panels on both sides and is used for high-quality signs and on the sides of RV’s. It comes in various thicknesses (we used 1/4 in.) and is very rigid and strong. It also looks great, cuts with typical woodworking tools, is reasonably economical (4 by 8 sheet is about $80-100 from a local sign supply company). We use small bolts, nuts and washers to mount components. It comes in various colors and can often be used for other components on your robot. Check http://www.laminatorsinc.com/sign-panels/products/alumalite for more information. Alumalite was used to make the trailers used on field a few years back.
We have also used corrugated polycarbonate sheets. These are extremely light weight, very tough, mostly rigid and easy to work with woodworking tools. This product is used in roofing and wall panels in greenhouses and can be purchased from your local plastics supplier. McMaster Carr also has a similar product. It comes in a variety of thicknesses. If you are mounting a lot of heavy components, I’d use 3/8" - 1/2" thickness, but light weight components can easily go on a 1/4" piece. To keep bolts from pulling out, use washers, maybe fender washers on heavy items. Again, this is not a very expensive product that will save a lot of weight. Do a search for “corrugated polycarbonate” for more information, or run over to your local plastic supplier to see it.
IDK what it’s called, but one of our mentors works somewhere where they use these things and throw out the leftovers, so we get as much as we’d like! It’s not only really sturdy, and really durable, but it’s extremely light, too! Love the stuff, and I hope to use it on the 2012 bot (if applicable).
If you get a chance you need to talk to IndySam about it. They use honeycombed aluminum on their FRC robots and know a lot about it. I am sure he or any of the guys from 829 would be happy to answer any questions you have on it. They are good people and always happy to help.
Team 1515 uses coroplast (corrugated plastic sheet, much like plastic cardboard) for E-boards. They are incredibly versatile, and can be cut with a wide range of tools. I tend to dislike Honeycomb composites primarily because of their tendency to deform. They have a fairly low shear strength, and cannot take any major hits.
Just a thought: Has anyone tried or thought about making a drivetrain from this stuff? I mean, it’s durable, really light, and really sturdy! Plus, if you get a semi-thick sheet of it, you can just carve out the center and you have your base and everything! Cut out holes, etc. to get the wheels in, and keep anything needed to mount motors, etc.
Yes. Team 1836’s 2008 robot (one of the small sprinters) was made largely of honeycomb aluminum and spacers. It was really light and incredibly fast until we lost control and hit a wall. The devastating crash required the robot to undergo design changes and rebuilding. Team 1515 used it as a trackball guide (if I remember correctly) on their 2008 robot. I don’t have pictures, but it is completely bent out of shape.
For the past two years, team 418 has used 1/2" Kevlar honeycomb for structural panels/electronics mounting. We get it from a contact in the aerospace industry (apparently, it’s the stuff used to make floors in airliners). It cuts fairly well with a circular saw, although cutting tends to generate a lot of dust: do it outside. While it is very strong and rigid, the faces are not very tough. That is, a sharp impact (say a ball-peen hammer) can crack the surface. For the same reason, we generally use large diameter washers when bolting or riveting through it.
Although I’ve never used it for robotics, I’d consider giving this stuff a look. It consists of two thin sheets of G10 fiberglass or carbon fiber, surrounding a honeycomb structure made of nomex. I’ve used it for a number of things in high power rocketry, and can confirm that it’s great stuff…very rigid, and almost unbelievably light. Not something that I’d want to put in a spot way out in the open, but it can take a hit if need be.
I have cut it with both dremels and bandsaws without issue, beyond those typically associated with cutting fiberglass (be careful with the dust!).
While honeycomb materials may be good for some apps on the bot, they tend to be expensive. An alternative to the 1/2" plywood would be to take a piece of 6mm or 1/4" birch plywood and laminate a layer of 5 - 6 OZ carbon fiber to it. You’ll get a very ridged and impact resistant material. We do this for our electronics board and other parts. The goal being to introduce the students to some composite construction. You could make your own honey comb stuff but it is more difficult than the plywood and carbon.
Not as durable and sturdy as you think. It’s strong as a sheet, but easily damaged by impacts - something FRC bots see a lot of. However if you consider and manage that, it is something to consider.
Or use plain old Fiberglass, tons cheaper than CF and plenty strong.
Or make your own composite with thin foam (available as insulation at Home Depot/Lowes) covered with a layer of fiberglass. Just use Epoxy resin, as Polyester resin will melt the foam. Buy small quantities of foam, fiberglass and epoxy resin and give it a try.
Team 610 last year used 1/8th inch lexan for their electrical panel, and found it to be a suitable material to use. It was relatively strong and rigid, yet flexible enough to be able to take a hit without cracking. For affixing our components, we used zip ties to attach all components except the larger ones such as the cRio and Power Distribution Panel. We were also able to cut out the panel with some of the mounting holes on our CNC router very easily, which was another plus. From our experiences with the material, I would highly recommend using 1/8th inch lexan for your electrical panel.
This may get the 2011 bizzare idea award, but ive wondered if one could use corrugated 2-ply or 3-ply cardboard, similar to what appliance boxes are made from.
cheap, easy to obtain, light, and eco-friendly! also easy to work with if you have a good, sharp utility knife.
again, fender washers reccomended. also for heavy things, you would want to use some sort of back support to add support.
another thing i have seen used is 2" grid plastic, like used as florescent light diffuser panels.the 1" stuff is too weak, as in 2009 on 1747, I learned that it was a poor material for electronics mounting (sags). the thicker 2" grid works, as i have seen teams like 461 use it in the past. to mount things, you use zip ties to loop around the gridwork.
In 2008, one of our mentors got some small pieces of scrap titanium honeycomb from his job. We originally used it for ultralight forklift prongs for the trackball, but when that design didn’t work, we ended up using another piece as a shooter disk attached to a pneumatic cylinder. The titanium was quite possibly the scariest thing we ever machined, and the mentor who was supervising the fabrication told us that it could easily catch fire and that if it did, we would not be able to put it out. As I recall, his advice if that happened was to, “throw it on the concrete floor and run away”. The titanium really wasn’t worth the trouble and we got no real advantage from using it, other than that it sounded cool. I can’t speak for other honeycomb materials, but they definitely might be worth looking into.
i remembered building adult sized chairs in 8th grade using masking tape and 2-ply monitor boxes for a shop class… i figured if one could make a reliable chair from it, then one could make electronic boards and perhaps other items from it.
last year my team used a quarter inch thick honeycomb fiberglass board for our belly-pan electronics board. velcro tape didn’t stick to it and you have to put washers on sides that a bolt head or nut would normally touch because you would be able to pull them through. other than that it was great cause it was light and durable