How are bellypans made?
 

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.

Re: How are bellypans made?
 

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!

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

We used 1/8" ABS and it's a little flexy.

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

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?

Re: How are bellypans made?
 

Bellypan usually has electronics on it, but it's generally the bottom part of the robot with cut cross sections into it.

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

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

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

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...

Re: How are bellypans made?
 

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.

http://www.emplastic.com/images/library/BC_Twinwall.jpg

Another way to cut sheet plastic is to use a very fine blade, mounted backwards, on a circular saw.

Re: How are bellypans made?
 

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.

Re: How are bellypans made?
 

To give the students some exposure to composites, we use a piece of 1/4" plywood laminated with 6 oz. carbon on both sides.

Re: How are bellypans made?
 

Where to do you get yours? Can the 6061 be waterjetted instead?

Re: How are bellypans made?
 

Any metal supplier will have 6061 sheet. Yes a waterjet works the same.

Re: How are bellypans made?
 

Thanks!

Re: How are bellypans made?
 

Last year we used a honeycomb fiberglass, the only problem was that some adhesives, such as Velcro tape, did not stick well. You can drill holes for support but you must have washers along with the nuts for the bolts.

Re: How are bellypans made?
 

We use this for mounting electronics and other materials. Lightweight, easy to mount to, easy to work with -

http://www.andymark.com/product-p/am-0836.htm

Re: How are bellypans made?
 

Use fiberglass instead carbon if mounting electronics, or coated it with some clear coats. Same with using aluminum sheet, paint it so it's not conductive. I've seen too many times a live wire come loose and touch the mounting board. Also instead of plywood, use a foam core and save yourself a ton weight!

Re: How are bellypans made?
 

We CAD ours and a sponsor water-jets it from 1/4 inch aluminum. We then tap directly into it and attach our electronics that way.

Previous to this we used ABS and nuts and bolts. However, in 2010 and 2011 we had so little clearance under the robot that we had to tap the baseplate or countersink flat-head bolts from the bottom up.

Re: How are bellypans made?
 

Last year, 1370 used 3/4" plywood (Lowes) to mount all of the electronics on. This year, because we were afraid of the weight limit (rightly so, it turns out), we used 1/8" Lexan. Band saws, vertical mills, and circular saws with either forward or reversed blades works just fine. Unfortunately, our Lexan was a little too gummy to use the tried-and-true method of score it and snap it at the line.

Re: How are bellypans made?
 

2079 laser cuts 1/16 5052 aluminum sheets. The only reason we use 5052 is because we put flanges on the edges, but 6061 is stiffer (or at least a standard T6 temper is). Our shop doesn't like to laser thick aluminum because of its reflective properties that damage the laser, but if you want to do thick stuff you can use a waterjet. I don't see a need to use anything thicker than 1/8 for a belly pan anyway, but I guess there could be a reason sometime.

Re: How are bellypans made?
 

6061 T6 is not stiffer, but it is stronger. Nearly all aluminum alloys have essentially the same stiffness (elastic modulus).

Re: How are bellypans made?
 

We used .09 laser cut 5052-H32 sheet. It was bent with the back piece of the chassis as the flange (suggested to us by Sean from 2415). We did not add much lightening this year, but for next year we will definitely be using the diamond pattern commonly used by 254 etc.. Here's a picture

Re: How are bellypans made?
 

If you can score and snap it, it's not polycarbonate! It's most likely acrylic (Plexiglass).

I'm not too keen on starting with a material that needs a lot of cutting to make it do the job, for any part of the robot. But I guess if you have access to machinery that can do this, and you like drawing neat designs in CAD, then it kind of makes sense. We usually do fine with a sheet of plywood, of a suitable thickness for what's attaching to it and how big of an area it spans.

Re: How are bellypans made?
 

I have used 5052 and 6061 on belly pans with great success in each. The 5052 does flex a smidge more I found, but overall does what it needs to. Its what the sponsor had on hand at quick supply so we dealt with it. Even had to cut one of the belly pans in half since we had parts that didn't hit the tolerance we needed by some random chance. I'm not sure what happened but the bending was free so I'm not complaining.

- Andrew

Re: How are bellypans made?
 

I don't like to use bellypans, there are much more efficient places to place all of your electronics.

Re: How are bellypans made?
 

You can score and snap polycarbonate. We do it all the time for making hoppers/boxes etc.



As for belly pan. We are using 1/8" 6061-T6 with a waterjet doing the cutting for us. We anodize the bellypan and it is then riveted to our frame. The electronics are held down using plastic screws tapped into the bellypan.

Also- if you do cross-hatching like 254 and ourselves do for lightening, the "vent" tool in SolidWorks is your best friend.

Photo:


-Brando

Re: How are bellypans made?
 

Some of the design parameters for this years chassis was to be lightweight, easy to maintain, simple to make. We used a CNC punch press to punch out our drive base. The material is .090" 5052. Note the simple round holes in a stagger for lighting the material.

The Cad team came up with a innovative way to incorporate the belly pan into the front and back panels. The side rails slide into the belly pan and are riveted together. We call it the clam shell design.

We use .250 high pressed in standoffs, a plastic isolator and nylon screws to attach electronics.

This chassis weighs in under 12 lbs and is very rigid and strong.

https://picasaweb.google.com/1045493...89068712771618

http://www.youtube.com/watch?v=znSKHoLEN5U

Re: How are bellypans made?
 

This year we used the most beast of beast baseplates... We have a 40lb 1/4 hardened steel baseplate. We could run over a landmine and likely not be too damaged (except from being thrown into the air).

As Hannibal said in the A-Team, "overkill is underrated".

Re: How are bellypans made?
 

Based on my experience, this is true, but it doesn't always snap where you score it :rolleyes: . (I was lazy, it was 1/4 inch makrolon, I scored it with a dremmel.)
The groove wasn't of a consistent depth, this was made worse by the fact that melted debris had re-hardened to fill in other parts of the groove. After (ALMOST literally) jumping up and down on it for a while, it snapped along the grove for a couple of inches after which the break line made a slight turn splitting nearly parallel to the line for the rest of the split. It was ugly, but still close enough to the desired size to use (luckily it split in a way that I wound up with extra material instead of missing material.)

Re: How are bellypans made?
 

Seconded. A vertical board is much more space efficient.

Re: How are bellypans made?
 

we have both

Re: How are bellypans made?
 

We went with a 45 degree angle on our electronics board this year...best of both worlds.

Re: How are bellypans made?
 

We use two pieces of corrugated polycaronate (http://www.mcmaster.com/#corrugated-...sheets/=gnf1k0) refer to the image labeled non-corrugated. it is also called corriboard or corrugated plastic. We use two 1/8" thick pieces with the channels running in opposite directions. use srews or bolts to attach. We use an ice pick or pin to poke a hole where we want the screw to go, and then use 10-24 bolts, not screw, to attach. They tap themselves into the plastic, and the connection is sturdy without a nut as long as you dont detach and reuse the hole many time. Good Luck! Hope to see it in action next year!