Body

[Brent]

We've used three different methods for making body molds this year. How do you make the molds for your body?

[Ben Beacock]

We started with chicken wire to get the basic shape then laid wet paper towel over that and applied plaster. The plaster was formed to the final shape and a female mold was laid with fibreglass. The female mold was removed, split in 2, and reinforced. We then fibreglassed to make the final part(nice and smooth). Add in lots of sanding, wax, and gelcoat inbetween those steps.

[vinHonda]

MDF board glued together, CNC'd out to become our female molds. The male parts came out nice.

Pics are on our website somewhere.

Vinh

[Scott Doolan]

MDF frame, high density polyurethane foam shaped, sealed, polished, gelcoated, fibreglass female mold off this, polished then lay carbon.

Takes a long time and is very messy with foam dust going everywhere.

scott

[James Waltman]

Pretty much the same way Scott said above. We have used this method to make a lot of molds here. It seems to work well. Viking 32's Body was also made this way.

Check out these other discussions for some pictures of Viking 32's body construction.
Firewall seperate from seat? (http://fsae.com/eve/forums?q=Y&a=tpc&s=763607348&f=125607348&m=25210205111&p=2) Got a little off topic.
The other day at the VRI (http://fsae.com/eve/forums?a=tpc&s=763607348&f=648600998&m=74010383211&ORIGINAL_REFERRER_URL=http%3A%2F%2Ffsae.com%2Feve% 2Fubb.x%3Fa%3Dtpc%26s%3D763607348%26f%3D648600998% 26m%3D74010383211)

[Nate Notta]

Vin,

When you used MDF board to CNC the mold... What did you use to glue the MDF together?

[Andycostin]

We used the same type of MDF idea, but each sheet was cut to shape individually, then stuck together in three parts that were mated to make the final mould. Very labour intensive, and we think that we may have found a better way to go this year, CNC sounds like the idea.

[Big D]

yes, CNC is excellent. Take your model of the chassis in Solidworks (or whatever you're using) and make a solid that pleases your eye, and conceals that frame. Then simply use insulation foam to create that part in your CNC mill, paint with HOUSEHOLD primer, pull a female mold off that, etc.

or if you want to be more old style, and have an excessive amount of time on your hands, sculpt what you want using styrofoam, wood, chicken wire, drywall mud, etc. This is how I made our nose cone last year, and how another guy did the seat.

Speaking of seats, does anyone have a better way than trial and error fitting of a male mold, then pulling a female off it, and the final out of that?

[Joel Miller]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Big D:
Speaking of seats, does anyone have a better way than trial and error fitting of a male mold, then pulling a female off it, and the final out of that? <HR></BLOCKQUOTE>

We cast the seats directly from our drivers' bodies. Warm, sloshy, smelly expandable foam. Fits great. I could fall asleep in there...

[Big D]

Joel, could you elaborate a bit? we tried what you describe.... dressed a driver in a garbage bag, and then sprayed expandable foam around him, but it just made a mess. What expandable foam product did you use? what is involved in finishing it into a seat after you pull yourself out of the goo?

[BStoney]

Dan,

Try a two part foam in a bag to start your mould. Just have your driver get in a driver's suit cuz it get's kinda warm http://fsae.com/groupee_common/emoticons/icon_wink.gif I will check what kind of two-part foam we have here in the shop when I get out of class. (FSAE.com is definitely better than lecture right now... http://fsae.com/groupee_common/emoticons/icon_biggrin.gif)

[MikeWaggoner at UW]

Try mixing the 2 part foam beforehand, and see how hot it gets. Some stuff gets to smoking hot, and you'll smell the stink of the foam and burning flesh...

If you mix the ratios a bit off, or mix in a filler, you may get a cooler foam (tho it will expand less)

[Big D]

we tried to use that MONO houshold expanding isulation foam stuff.... I dunno if it didn't work at all, or we just didn't anticipate just how much foam it takes, but it was a flop to say the least. What is the original purpose of your foam, i.e. where do I get some?

[Didier Beaudoin]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Big D:
we tried to use that MONO houshold expanding isulation foam stuff.... I dunno if it didn't work at all, or we just didn't anticipate just how much foam it takes, but it was a flop to say the least. What is the original purpose of your foam, i.e. where do I get some? <HR></BLOCKQUOTE>

The two-part foam Mike is talkng about is polyurethane that comes in two separate bottles. You mix both liquids and it expands (a lot) and then hardens. It can be found probably at the same place you get your resin for your composite parts. I know boating shops have some too.

[BStoney]

Try these out for a two-part foam solution...

http://www.aircraftspruce.com/catalog/cmpages/x30foam.php

http://www.shopmaninc.com/foam.html

[alfordda]

We have always gotten ours from Continental Motorsport. Just ask for some A/B Seat Foam.

http://www.continentalmotorsport.com/Aboutus.htm

[Joel Miller]

Dan,
We put the foam in a garbage bag, then sat the driver on it, shaping the bag around the driver. This saves a big mess, but you have to supply something such as a the brake pedal for the driver to press back on because it is slippery before it sets. Afterward, with apolstry and some wet laid glass fibre reinforcement, you have a fairly durable custom moulded seat.

[Big D]

do you guys leave the cured foam as your seat, or do you use it as a form to take fibreglass/carbon parts off of?

[Rob Davies]

Im interested in the seat idea and wouldnt mind if you could answer a couple more questions aboutthe two part seat foam.

Do you paint it or cover it in material or leave as is? or as stated earlier cover in glass fibre?

Do you glue this onto the undertray or what?

How do you get the harnes to work with this as our submarine straps currently loop around the glass fibre seet and this rubbing and forces may anhialate the foam.

Thanks, Rob

[Joel Miller]

Dan, Rob,

We use the foam as the seat. It is removable (not bonded in) because we have different seats for each driver.

Without reinforcement, the foam is weak and brittle and some sections will be very thin (around the shoulder blades and buttocks etc). The fibre reinforcement gives it strength and durability. Apolstery is used to make it look finished.

The seatbelt issues have to be worked out individally because each car will have a different driver recline and harness points. It is possible to have a slit in the seat through which the submarine strap can be fed.

The foam is fairly rigid and will fit the driver like a glove. Just make sure that when you cast your seat, the you are comfortable, straight and with hips pushed back (need some bracing to push back on with your feet so you don't slide forward and curl your back).

Good luck.

[Joy Pathak]

BUMP

Any new methods of body fabrication anyone has come up with or used since December 2005?

[NetKev92]

More Variations on assembly of a body plug:

http://p081.ezboard.com/Phoenix-F1K07-Images/fdsrforumc...ge?topicID=900.topic (http://p081.ezboard.com/Phoenix-F1K07-Images/fdsrforumcarbuilding.showMessage?topicID=900.topic )

This foam slice method is essentially what we used to build our plug for a DBF aircraft fuselage back in about '03. Pink foam at home depot or Lowes is hot-wirable or can be cut with sharp knives and determination. It sands easy with coarse grit in the 60 to 80 range making it fast to get the shape you want. If you glass the foam, you can bondo on top of the glass to work things to your desired level of perfection. Don't use polyester on insulation polysterene or you'll have a pile of goo. Test a piece for epoxy compatibility before you commit. Speaking with RC aircraft guys, blue insulation foam is chemically much like the pink stuff, but it tends to have more contaminants in it so you get more tear-outs and edge defects in hot wire.

For minimum cost and labor for a one-time tool, I highly reommend the foam. It's not glamorous, but you're only limited by how good you are at sanding to template fit.

If you're desperate to play with CNC'd parts, you can probably find someone with a hotwire CNC searching online. I use a guy out of texas with an online advert site when I need wing cores.

[Mike Hart]

Thanks for that link Kevin. Seems like quite a neat way to do it. Seems the guys making that car used water jet cutting which is pretty good. What would you suggest as a sealant for the foam? From what I can understand they used some kind of kitchen laminate! Any idea where you'd get such a thing?

[NetKev92]

I typically ignore small gaps and torn-up edges on the foam. You just need it close enough to glass over the roughed surface and get going.

If you want to try kitchen products, you can probably find it at Lowe's, Home Depot, or any larger hardware/construction store. The prices should be good too.

[Mike Hart]

So would you just take a mould straight off the styrafoam? Would this not take half the surface with it? I'll have to go and have a look in the UK equivalents of Loews and Home Depot. I'm sure somewhere here must have an equivalent product. I guess the big issue is checking it doesn't eat the foam!

[NetKev92]

No, you glass over it to give the foam a hard candy shell to do traditional bondo/paint bodywork on. When the bodywork's done, you have a good plug to pull female molds. You can pull parts straight off the male plug, but without female molds, count on doing some additional bodywork on the male-tooled parts. You'll be laying up on a smooth surface but the rough back-side of the parts becomes the outside of your car.

The thicker you make the glass layer on the surface of your plug, the longer it will tend to last if you want to pull more than one set of parts or molds. If you're making molds though, I'd focus on making the molds thick so you can chuck the plug and get as many parts as you need from the molds.

The tradition is Plug, Mold, Part if you want professional quality parts. Plug to Part can save some material if it'll be a one-off. In absolute desperation, you can even cut/melt the foam out after you lay-up over your foam, leaving one set of bodywork to bondo and prep. This is somewhat like the method to build a number of composite homebuilt aircraft. You sand a foam block to shape, glass it thick, melt out the foam with gasoline, and bondywork the thing to make it pretty. It's the brute force method to build one.

This is also why there are so many un-finished homebult aircraft in the world. They say a person only has so much sanding in them. If you run out before you get done...

[Joy Pathak]

Anyone ever think of using Lexan?

[Christopher Catto]

you kidding?

thats cool, like RC car. not bad idea. I think its not bad since you just get hold of a mega hot gun and just mould it around your buck.

as for seats, continuing the conversation on page 1, another possibility that does not involve such high temps is to get a bean bag (the one with polystyrene spheres where you dog sleeps or you if your bro brought back a girl), pour the spheres into a transparent bag (so you can watch it in case anything looks wrong), then pour in some resin.

get your driver to sit in and gauge if any of the polystyrene needs to be removed. give him a cuppa and a mag, then have someone point a hot gun at the bag. yeah, this does involve heat. sorry, but not really that much of a discomfort.

our technician at UH thought of this in 03 and we then laid up a mould. made a carbon seat with UH logo and it was made to wrap around the two main steel tubes of the chassis, at elbow level. seat was fixed by velcro and body weight. could be removed for access to data logger and fuel tank, in a manner that fulfilled the rules.

ok, so no F1 technology but hey, it was cheap. pity Jim was not as small as we thought so seat was quite generous.

[emerjer]

We use the expanding foam from aircraft spruce (posted on first page) and it works fine.

We have our drivers wear jackets cause it does get hot...throw a trash bag (big ones) behind/underneath the driver....and simply pour in the mix...

Sometimes we overfill and shave off the excess foam so that it fits nicer.

I'd say it's the quickest and cheapest way to make inserts/molds...

Cal Poly Pomona

[James Morris]

This is a odd method we work out to make the rear bodywork on our 07 car.
We got a fleecy blanket and stretched it over our naked chassis and pined it into position. Once it was in place we brushed a load of resin onto the material as it really soaks it up, then glassed over the top of that to make it real ridged. Once it was dry we popped it off and sanded down the inside and polished it up. And that's it, one female buck, to the exact dimensions if the chassis

[Joy Pathak]

Originally posted by Christopher Catto:
you kidding?

thats cool, like RC car. not bad idea. I think its not bad since you just get hold of a mega hot gun and just mould it around your buck.


Lol..... The Exassis....Transperant body....

[Christopher Catto]

Lol..... The Exassis....Transperant body....

yeah. The Exasis by Rinspeed/Bayer.

http://www.speedheads.de/artikelbilder/2007/RinspeedExasis2.jpg
http://pub.tv2.no/multimedia/na/archive/00304/Rinspeed__eXasis__k_304710g.jpg

I think though that the prototype was rather expensive. Dunno how thick the panels are. I personally like the plastic body panels in the Vette. Flexible and kinda tough, unlike the feel of thin glassfibre which can be a bit like crisps (chips, for north-americans) depending on the quality of your resin.

didnt a certain green fsae car have canvas-like body in fs03 with a transparent plastic rapid proto air inlet. Dartmouth. they now have carbon panels i think. is it legal to have bodywork that is highly deformable? would the judges complain about cling film? surely any sharp body can pierce a carbon or alum bodypanel anyway.

The idea of a female from the quilt impregnated by resin is awesome. maybe sell the idea to Lotus. they have RIFT (resin impregnation bla bla) for making one piece body. sell your idea as IABWR (impregnate a blanket with resin).

amazing what you can do at Uni, with some wacky technicians, clever students, little sleep and some disregard for ISO health and safety! then again laminating is a world of imagination and household materials. wish I could make titanium at home in my blender...

[flavorPacket]

i know of several teams (including mine) who used aircraft fabric for at least some of the bodywork. we stopped using it because some noobie would inevitably pierce it before competition.

[Mike Hart]

Yup. Our car used it this year, and also did two years ago. If done properly it looks as good as any other bodywork on large flat areas. Obviously the issues are getting complex shapes, but if all you want is to have really, really light bodywork, there is nothing wrong with it!

[NetKev92]

If you look at pictures of the Lotus Elise factory, they use a variety of composite molding methods. (Lotus Elise - The Complete Story, by John Tipler)

Nose and molds are soft tooling laid-up on a male plug. These female molds are used for wet layup.

The removable hardtop and door panels are built using a variation on RTM. The door molds are machined from a nickel alloy for durability. The removable hardtop mold looks like a traditional soft tool made from composites with a gelcoat surface but the caption did not specify and the text is unclear.

[Joy Pathak]

Originally posted by Christopher Catto:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Lol..... The Exassis....Transperant body....

yeah. The Exasis by Rinspeed/Bayer.
... </div></BLOCKQUOTE>

My point was..

.. Transparent body....Mmmmm....

Thats why I thought maybe use Lexan and just have a complete transparent body... haha