West Coast Drive: Bellypan

[Adam.garcia]

Hello,

Can the knowledgeable Chief Delphi community shed some light on what should go into the design of the West Coast Drive Belly Pan?

Main points I feel are:
1. What material/ How thin should the material be.
2. What lightening patterns have worked best for your team? How do you achieve this pattern using solidworks? (Would it just be a matter of using the linear pattern?)
3. How do you design the tabs and mounting holes into the bellypan to ensure correct spacing when bolting in the electronics?

Any other points of interest that I have excluded would be great.

Thanks,
Adam Garcia

[Borobo]

It all depends on the construction of the frame. in many WCD's the belly pan is made out of diamond cut alum., which contributes to rigidity, which can become a problem especially in thinner or less sturdily constructed sheet metal or 1x1/ c channel frames. in the event that you have a rigid and strong frame that doesn't need the extra support, I suggest going with something as light as possible, such as our material of choice this year, verilite.

to address 2, I would just create something and linear pattern it however you want.

don't really know much about 3, we just lay out our electronics, trace them with a dry erase marker, then drill holes accordingly

[Adam.garcia]

Originally Posted by Borobo

It all depends on the construction of the frame. in many WCD's the belly pan is made out of diamond cut alum., which contributes to rigidity, which can become a problem especially in thinner or less sturdily constructed sheet metal or 1x1/ c channel frames. in the event that you have a rigid and strong frame that doesn't need the extra support, I suggest going with something as light as possible, such as our material of choice this year, verilite.

I am unsure whether our frame is built rigidly enough to suffice without the diamond cut aluminum. For reference, our frame is very similar to 254's design. And, since they have been using an aluminum bellypan, I feel we should do the same! Oh yes, and it adds to the overall amazing look of the drive train.

[Starke]

Adam,

There are a lot of examples of different bellypan styles on FRC Designs. Check out the link to the Drives page below!

FRC Designs Drives: http://www.frc-designs.com/html/drives.html

Matt

[Adam.garcia]

Thanks Matt, I will take a look at these CAD Files

[sanddrag]

We used 1/8" ABS riveted to the bottom of our frame which seemed to work fine. It was a little flexy in the middle, but we added a support and then it was fine.

[R.C.]

Originally Posted by sanddrag

We used 1/8" ABS riveted to the bottom of our frame which seemed to work fine. It was a little flexy in the middle, but we added a support and then it was fine.

If your gonna go plastic, I'd recommend the stuff 973 has used in the past and maybe this year?

I believe its 1/16 or 1/8" thick garolite form McMaster. Adam can provide more details.

-RC

[AdamHeard]

Originally Posted by R.C.

If your gonna go plastic, I'd recommend the stuff 973 has used in the past and maybe this year?

I believe its 1/16 or 1/8" thick garolite form McMaster. Adam can provide more details.

-RC

1/16th G-10/FR4 garolite. Used it 2009, 2010 and 2012. It's very strong stuff and cuts very easily with hand tools. Tensile strength is greater than most aluminum alloys, and the bellypan in tension is really the loading that matters.

Aluminum bellypans are AWESOME, but are a substantial time and resource sink. I recommend any team that isn't already building 5-star robots to focus their time and resources on something other than a pocketed aluminum bellypan. The runtime on a bellypan for a 2d sponsor can cut several gearboxes, etc...

They sure are cool though

[Gray Adams]

Originally Posted by Adam.garcia

3. How do you design the tabs and mounting holes into the bellypan to ensure correct spacing when bolting in the electronics?

I assume you're using Inventor, but if you're not, I hope this is still pretty applicable. Once you have your pocketing pattern designed and applied in CAD, layout the electronics in an assembly the way you want them in an assembly. "Edit" the bellypan without "Open"ing it. This should cause everything else to become partially transparent and not selectable. Create a sketch on one side of your bellypan, and then go to the "Project Geometry" tool. Now when you mouseover the edges of all the parts in the assembly, they will light up, and selecting them will project that edge onto your sketch. You're essentially tracing all of your electronics. From there, go ahead and draw lines where you want them, close loops so the Inventor sketch doctor doesn't complain, and then extrude your tabs/outlines/whatever you just designed to mount electronics.

Little tabs at each corner are nice, but I like making a border for the entire component. It's cooler to look at when there's nothing on it.

[Gdeaver]

Every time the belly pan subject comes up I have the standard reply of "composites". This is the perfect place on the robot to give students some experience with composite construction methods. A team could use G-10/FR4 sheets. I suggest that teams make their own. A piece of 1/4", 4mm or 6mm birch plywood laminated with a layer on both sides of carbon fiber s2 glass or Kevlar makes a wonderful belly pan - electronics board and provides a great learning experience for the students. Once a team can make a flat sheet other forms can be experimented with. This year we used a .06" wall tube of layed up Kevlar for our beater bar. Took tremendous abuse and is extremely light. Put some fiber in your robots diet.

[sanddrag]

My experience with G10 Garolite was not as favorable. I found it difficult to cut and that it puts a lot of wear on cutting tools, and I'm not particularly fond of the dust from cutting it. The reason we went with 1/8" ABS was so we could tap it, then use Nylon screws and cut the screws flush with the bottom of the robot, for a totally smooth underside. The ABS is a little soft though, and requires care when tapping.

The garolite is nice and strong though, I'll give it that.

[Michael Blake]

Originally Posted by sanddrag

My experience with G10 Garolite was not as favorable. I found it difficult to cut and that it puts a lot of wear on cutting tools, and I'm not particularly fond of the dust from cutting it. The reason we went with 1/8" ABS was so we could tap it, then use Nylon screws and cut the screws flush with the bottom of the robot, for a totally smooth underside. The ABS is a little soft though, and requires care when tapping.

Generally, what size nylon screws do you use? And you get enough thread-bite at 1/8"?! THANKS!

[Adam.garcia]

Originally Posted by AdamHeard

1/16th G-10/FR4 garolite. Used it 2009, 2010 and 2012. It's very strong stuff and cuts very easily with hand tools. Tensile strength is greater than most aluminum alloys, and the bellypan in tension is really the loading that matters.

Aluminum bellypans are AWESOME, but are a substantial time and resource sink. I recommend any team that isn't already building 5-star robots to focus their time and resources on something other than a pocketed aluminum bellypan. The runtime on a bellypan for a 2d sponsor can cut several gearboxes, etc...

They sure are cool though

I completely agree. I am still unsure whether we are going to create the WCD custom Bellypan or just use a sheet of garolite or ABS. Do you know the densities of each? I cannot seem to find those numbers.

[Adam.garcia]

Originally Posted by Gray Adams

I assume you're using Inventor, but if you're not, I hope this is still pretty applicable. Once you have your pocketing pattern designed and applied in CAD, layout the electronics in an assembly the way you want them in an assembly. "Edit" the bellypan without "Open"ing it. This should cause everything else to become partially transparent and not selectable. Create a sketch on one side of your bellypan, and then go to the "Project Geometry" tool. Now when you mouseover the edges of all the parts in the assembly, they will light up, and selecting them will project that edge onto your sketch. You're essentially tracing all of your electronics. From there, go ahead and draw lines where you want them, close loops so the Inventor sketch doctor doesn't complain, and then extrude your tabs/outlines/whatever you just designed to mount electronics.

Little tabs at each corner are nice, but I like making a border for the entire component. It's cooler to look at when there's nothing on it.

This was very helpful. If we decide to create our own custom bellypan this summer, then I will be sure to employ these methods. This is actually along the lines of what I was thinking, but it was helpful since you gave a more in depth description of what to do.

Thanks!

[AdamHeard]

Gdeaver, why use plywood for that? That thickness plywood is already almost overkill for strength, why not use foam as the web of the composite?

Dave, the garolite cuts easily on a waterjet, tablesaw, and with hand tools. We have only ever specifically used g-10/fr4 so I can't comment on how g-10 cuts.

Originally Posted by Adam.garcia

This was very helpful. If we decide to create our own custom bellypan this summer, then I will be sure to employ these methods. This is actually along the lines of what I was thinking, but it was helpful since you gave a more in depth description of what to do.

Thanks!

I highly recommend you do not do a custom aluminum bellypan, the time and resources used on it would be much better in other areas.



A large factor in the decision is whether or not the bellypan is part of the frame. I believe a bellypan should be an integral frame member (connecting corner to corner in tension) for maximum weight and strength efficiency. If this is not the case, the material selection is far easier. If you want a structural bellypan, the suggestions in this thread are good.