I’m working on ideas for next year’s robot, but I’m curious how most teams make their bellypans. Most likely it’s waterjetted, or laserjetted, but there may be other ways I don’t know about.
Also, what material do you use, and of what thickness?
Thanks a bunch! I’ll post results sometime next year when it gets made!
PS. The bellypan I’m talking about is the one like 233/254/968/1323/971(I think)/1868 etc etc.
We’re using 0.188" nom. (3/16") Lexan cut on a bandsaw. Substitute any ol’ saw for a bandsaw. Don’t saw too quickly or feed too slowly or, as with a wide majority of plastics, it will start to melt and gum up. Easy peasey.
Hope that helps!
12 mm birch plywood. Cuts nice with a table saw. Screw the electronics parts down with wood screws. Quick and easy. If you need to drill a hole, the shavings are non-conductive. We used it even back when we used to make the rest of the robot out of metal. We do sometimes do some cutouts or partial cutout/rib patterns with a router.
We like to have a solid surface on the bottom of the robot when there is any chance it could be tipped over and another robot could run into the bottom, like this year. I’m toying with the possibility of cutting a set of ribs out next year on a CNC router (if I can find access to one) and then fiberglassing it. It will depend on the game and on what the weight / cost / hassle trade-off analysis ends up saying.
We used 1/8" ABS and it’s a little flexy.
Most people use waterjetted aluminum, which is then sometimes powder coated. I think it is probably 3/16 or 1/8 aluminum.
My team, on the other hand, is using black carbon fiber honeycomb (1/4" cell width). it comes sandwiched between two other peices of carbon fiber. it is very strong, light, and you can mount electronics right to it because it isnt conductive. be careful though, you must use VERY big washers when mounting to it so you dont pull the bolt right through it.
I don’t believe ALL carbon fiber is non-conducting (the surface is, but once you drill holes in it, that can expose conductive stuff), it’s always best to check first.
My team mounts electronics with Velcro on a 1/8" plastic base plate (I’m not sure if it’s ABS or polycarb off the top of my head). This year, the plastic plate was held to the frame with more Velcro and (rather ugly) plywood struts to keep it from flexing.
By “Belly Pan”, I assume you mean to put electronics on?
Bellypan usually has electronics on it, but it’s generally the bottom part of the robot with cut cross sections into it.
We tried some 1/8" aluminum laser cut for us (rev A had serious warping, although rivets fixed it. They built a fixture of some sort for rev B). It works pretty well if you use nylon screws to attach your electronics. I hear the new cRIO is coated so that it’s non-conductive, but it’s fairly easy just to toss a thin sheet of plastic underneath. We had to cut out our belly pan due to weight constraints though, and now our electronics are sitting on some 1/8" lexan.
We do ours like like Pink -> 254 -> 968 etc…
Basically 6061 - T6 Aluminum @ 1/8th thick.
We basically start off by making the diamonds, then adding elc holes/cutouts into it. Finish the CAD, send it off to a laser guy and its all g2g from there.
-RC
We do ours like like Pink -> 254 -> 968 etc…
Basically 6061 - T6 Aluminum @ 1/8th thick.
We basically start off by making the diamonds, then adding elc holes/cutouts into it. Finish the CAD, send it off to a laser guy and its all g2g from there.
We do basically the same. 6061-t6 0.125" (our t shirt cannon is .1875, but that is over kill)
In our CAD we started with the sheet, then patterned diamonds, then spaces for sprockets, gearboxes, and then holes for mounting electronics. Takes about 45 minutes on an OMAX waterjet.
We did 5052 because we put a few bends in it. I’m sure 6061 would have been ok too, but 5052 is a good option, especially depending on what’s available in terms of stock and what you’re doing to it.
If you don’t have access to waterjet/CNC facilities, you could just stick a thin aluminum plate on the bottom. The NERDS used .060" Aluminum for a bellypan in 2008; nice and sturdy with lots of real estate to attach stuff.
1/4" plywood works wonders, lightweight and cheap! currently my material of choice for something like an electronics board/bellypan. We’re sporting quite a bit of plywood on the Falcons’ robot this year.
We played with some mystical Boeing honeycomb composite material this season, glued between two sheets of paper (yes, like printer paper). Extremely light and stiff. The plywood was faster and easier to use though, so it won out. Maybe next year…
http://i.imgur.com/twuxEl.jpg](http://i.imgur.com/twuxE.jpg)
http://i.imgur.com/13U64l.jpg](http://i.imgur.com/13U64.jpg)
We use a material called verolite which is what greenhouses are made out of, it is essentially corrugated polycarbonate. We choose this material for several reasons
.5 inches thick (roughly) means that despite being incredibly light, it has excellent rigidity.
2.17 per square foot from our supplier makes it substantially cheaper than other materials.
It is non conductive, machinable with wood shop tools, doesn’t splinter or crack(it is spry enough that it would take an enormous amount of force to reach its ultimate yield point.
our dual belly pans(one on top of the other) weigh < .1 lbs each, and the 15mm thick variety of verolite that we use is stronger than half inch thick particle board by far, and although it flexes more it has higher ultimate yield properties than almost any type of plywood.
This year almost 2 full 4*12 sheets made it onto the robot.
Another way to cut sheet plastic is to use a very fine blade, mounted backwards, on a circular saw.
FRC2168 has been using this stuff the last few years: McMaster 84825K89
I learned about it while at college with FRC229, they used it for their ramps back in 2007. It’s listed as Noncorrugated Panels, is about 1/4" but the stuff is super light weight and can handle a good amount of weight.
Note: I’ve heard it called Polygal, but I believe that is the whole Kleenex vs tissue paper argument.
To give the students some exposure to composites, we use a piece of 1/4" plywood laminated with 6 oz. carbon on both sides.
Where to do you get yours? Can the 6061 be waterjetted instead?
Any metal supplier will have 6061 sheet. Yes a waterjet works the same.
Thanks!
