pic: Team 3647 West Coast Drive

[LondonBoy29]

Looks really good and I am excited to see how it turns out and how successful it is.

[Ether]

Originally Posted by Andrew Schreiber

How do you feel about plywood, yeah it is ugly but it is cheap. How effective do you feel it would be?

I don't have a link handy, but I recall seeing a recommendation to use thin plywood with fiberglass cloth bonded to it with resin.

[JesseK]

Originally Posted by Ether

I don't have a link handy, but I recall seeing a recommendation to use thin plywood with fiberglass cloth bonded to it with resin.

I remember that too, somewhere. It might have been Baltic Birch though, which is a bit lighter than plywood and commonly comes in multiples of 1/4" thickness.

[Ether]

Originally Posted by JesseK

It might have been Baltic Birch though

Yes, I think you're right.

[Brandon Holley]

The belly pan is the perfect place to use composites. Very rigid, very light, usually very thin and also non-conductive. I highly recommend a fiberglass or carbon fiber belly pan.

Making a composite panel yourself is also something just about any team with a vacuum pump can do.

-Brando

[Akash Rastogi]

Originally Posted by Brandon Holley

The belly pan is the perfect place to use composites. Very rigid, very light, usually very thin and also non-conductive. I highly recommend a fiberglass or carbon fiber belly pan.

Making a composite panel yourself is also something just about any team with a vacuum pump can do.

-Brando

Just make sure that if you use fiberglass for your bellypan that you're not 816 and have it end up being 8 pounds, un-lightened.

[thefro526]

Originally Posted by Akash Rastogi

Just make sure that if you use fiberglass for your bellypan that you're not 816 and have it end up being 8 pounds, un-lightened.

Was 8 pounds lightened, bro. 3/8" Thick Fiberglass Sheet Was Overkill for a bellypan, but you can't beat free.

(Until you're trying to figure out where you have 5lbs of weight that shouldn't be there.)

[EricH]

Originally Posted by Ether

I don't have a link handy, but I recall seeing a recommendation to use thin plywood with fiberglass cloth bonded to it with resin.

Originally Posted by JesseK

I remember that too, somewhere. It might have been Baltic Birch though, which is a bit lighter than plywood and commonly comes in multiples of 1/4" thickness.

Just a couple of days ago, too!

Originally Posted by Gdeaver

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.

This is in the thread discussing honeycomb material.

330's used various bellypan material; I believe we used 1/4" Baltic Birch in 2005 and built areas that weren't running under structural frame members up to 1/2" with glue. In 2007, using plywood, a pattern was traced on the bottom to allow electronics to be supported and have extra material around screws, then the whole thing was routed out. From the top, it looked solid because we didn't go all the way through.

[Brandon Holley]

Originally Posted by Akash Rastogi

Just make sure that if you use fiberglass for your bellypan that you're not 816 and have it end up being 8 pounds, un-lightened.

Originally Posted by thefro526

Was 8 pounds lightened, bro. 3/8" Thick Fiberglass Sheet Was Overkill for a bellypan, but you can't beat free.

(Until you're trying to figure out where you have 5lbs of weight that shouldn't be there.)

How have I not heard of this monster bellypan before??

A nice think piece of birch wood wrapped in fiber, soaked in resin, and vacuumed should give a VERY rigid, VERY light belly pan.

[Akash Rastogi]

Originally Posted by Brandon Holley

A nice think piece of birch wood wrapped in fiber, soaked in resin, and vacuumed should give a VERY rigid, VERY light belly pan.

That's actually what we'll be doing this year at Boeing's composites lab and autoclave. If the composite bellypan works out, we will also be making other structural members using other composites. Having so many Boeing structural engineers has its perks.

[JamesCH95]

Originally Posted by Brandon Holley

The belly pan is the perfect place to use composites. Very rigid, very light, usually very thin and also non-conductive. I highly recommend a fiberglass or carbon fiber belly pan.

Making a composite panel yourself is also something just about any team with a vacuum pump can do.

-Brando

To expand on this a little...

Carbon fiber is conductive, so be careful when mounting electronics on or near it. A member of my FSAE team thought a carbon fiber battery cover would be awesome, right up until the battery got set the cover on fire!

Decent composite panels can also be made with a clean, flat surface, a clean flat plate, and some weights. Though a proper vacuum setup is the way to go. You can also get mixed fiber composites to add a nice flair of color to your robot.

[Brandon Holley]

Originally Posted by JamesCH95

To expand on this a little...

Carbon fiber is conductive, so be careful when mounting electronics on or near it. A member of my FSAE team thought a carbon fiber battery cover would be awesome, right up until the battery got set the cover on fire!

Decent composite panels can also be made with a clean, flat surface, a clean flat plate, and some weights. Though a proper vacuum setup is the way to go. You can also get mixed fiber composites to add a nice flair of color to your robot.

Thank you for the clarification- I did reply too quickly.

Listen to James advice on this one!

[Ninja_Bait]

Originally Posted by JamesCH95

Care to elaborate on that? For example, I'd find it very hard to believe that a 1/4" pop rivet (steel or aluminum) is better in shear than the shank on a graded 1/4-20 bolt.

A properly designed and setup bolted joint can sustain more shear loading than the bolts themselves alone. The friction between the two parts, as generated by the clamping load of the threaded fastener, carries a substantial amount of load in addition to the bolts. Can the same be said for rivets?

I looked it up: Pop Rivets vs. Bolts

These are two kind of arbitrary sources, but it shows that while rivets are not quite as strong, they're comparable. The steel 1/4" rivet (shear: 2750 lbs.) beats Grade 2 1/4" bolts (shear:~2200 lbs.). However, the higher grades outmatch the rivets by a lot.

[AdamHeard]

Originally Posted by Andrew Schreiber

How do you feel about plywood, yeah it is ugly but it is cheap. How effective do you feel it would be? I know that 1114's Kitbot on Steroids uses 3/4" plywood for their electronics mount.

3/4" plywood would work just fine, but would be quite a bit thicker/heavier.

For a small wheeled west coast drive like this, a thin bellypan would be better.

[Chris is me]

Originally Posted by thefro526

Was 8 pounds lightened, bro. 3/8" Thick Fiberglass Sheet Was Overkill for a bellypan, but you can't beat free.

You can be extremely aggressive with lightening in fiberglass and still retain your structure, because it's just so rigid. Holes with as little as 1/8" - 1/4" of material left around them are possible.