I plan on adhering strips of polystyrene foam (the stuff coffee cups are made of) between each of the ribs of my plug and cutting those to shape with a hotwire. Then covering the entire structure with drywall filler, sanding, and hi-fill primer to finish at 600 grit. Similar to Alan's Meerkat plug construction method except Alan started with a hardboard sub-structure.

I am thinking that the end product may be too fragile to pull a mold from since it will be filler directly over foam.

Do you think that I should encase the foam under a single layer of fiberglass cloth (6oz) before moving on to the drywall filler?

Here's where I'm at:

4 Ribs on car - Bodywork

Dunno, but its the biggest CD rack I have ever seen

how thick will the end layer of filler be? if its over 1cm i feel it would be ok. how about putting some batons in between the ribs, to add some more firmness?

looking good anyway!

seriously, try some thermoplatic packaging wrap, staple it to the formers, wave a heat gun at it and in a few seconds it will be as tight as a drum - very smooth too. you can get it from packaging wholesalers

quote:

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Originally posted by Mark Allanson
seriously, try some thermoplatic packaging wrap, staple it to the formers, wave a heat gun at it and in a few seconds it will be as tight as a drum - very smooth too. you can get it from packaging wholesalers

---

I wonder if you can adapt model aircraft techniques.....

they cover the structure with tissue and then use dope (nowt druggy) over it that makes it go tight and firm.

Would be too delecate for your mould, but I wonder if some other tissue type substance could be made to do the same..... I wonder if grp tissue would shrink in the right way if used with aircraft dope......


atb

steve

To clarify, we are talking about deleting the styrofoam step and using a thermoformed skin (or some other skinning method) that is then covered and shaped by filler (drywall mud) to final shape?

The thing about foam is that although it is soft and spongy, at least there is some rigidity when applied between all the ribs. It's the spongyness that worries me.

summat like this?

http://www.jperkinsdistribution.co.uk/list.php?subcat=58&cat=Solarfilm%20products&Navmain=Covering


prob too delicate, but there must be something heavier weight...

[Edited on 4/6/04 by stephen_gusterson]

A few cents worth of ideas. One way I've seen small molds done is using a water based latex exterior paint over the polystyrene and then using body filler. A larger mold (full car body) filled the space in between the formers with rigid foam (though I'd guess styrene would probably be acceptable given the following step) and covered it with CSM and then body filler. I know that made for a very hard shell that they pulled molds off of. At least on this side of the pond we can get urethane foam insulation from home supply stores for very similiar price as styrene, and doesn't break down to the polystyrene resin. Otherwise you;d be stuck with using epoxy and the ensuing price. One guy I spoke to said he'd never use plaster again, and I can see where the difficulties lie, but hey, its dirt cheap and leaves a nice surface. Just a ton of work. Can't wait to see it done though. Cheers!

I was pricing styrofoam once, and was surprised that it is not so cheap! If you haven't bought yet, you might want to consider pour foam. 40 cubic ft of 2 lb. density ought to be plenty, and easier to work with than styrofoam:

http://www.fiberglasssupply.com/Product_Catalog/Pour_Foam/pour_foam.html

Mark's shrink plastic would be a cool way of sealing off the bottom of your forms for pouring.

A layer of FB cloth over the foam would be cheap insurance, IMO.

The form's looking great!

Pete

quote:

---

Originally posted by stephen_gusterson
I wonder if you can adapt model aircraft techniques.....

they cover the structure with tissue and then use dope (nowt druggy) over it that makes it go tight and firm.

Would be too delecate for your mould, but I wonder if some other tissue type substance could be made to do the same..... I wonder if grp tissue would shrink in the right way if used with aircraft dope......


atb

steve

---

blue foam makes for a good master, easy to shape too, made a few model aircraft from the stuff, worth a look at.

I have not been able to source the blue foam (Dow/Corning) anywhere locally. Can anyone (state-side) give me a place to go for this stuff?

Pete, the pour foam would be cool, but it is $180. I have to calculate how much the styrofoam will cost. Maybe it will be more?

If I glue the styrofoam to the ribs with liquid nails, then hot-wire it to rough shape and finally cover it with drywall mud, I shouldn't have to worry 'bout needing epoxy resin for my mould? The underlayment of styrofoam would be encapsulated by the drywall mud and the primer coats... Am I missing something here?

The pink stuff should work just as well. Home Depot has a sale right now, 3/4" X 4' X 8' for $10.45. This is only 2 cubic feet

Really, I think your best bet is going directly to manufacturers, industrial and trade distributors, etc. Your sale will be peanuts to them, but I'll bet somebody will be glad to help. There are polyurethane pour foams used for insulation, packaging, landscaping, etc., so hopefully you can find something Locost. Be sure to specify ridgid foam, and you may want to ask about fumes from hot-wiring.

Found this list for your area:

Plastics - Foam
Biofoam Corp
3035 N Maple
Mesa, AZ 85215
(480) 854-7000

Custom Packaging Products Inc
5601 S 24th St
Phoenix, AZ 85040
(602) 232-2747

Excalibur Enterprises
8813 N 55th Dr
Glendale, AZ 85302
(623) 939-6107

Foam Block Construction Co
501 E Plaza Cir #4
Litchfield Park, AZ 85340
(623) 935-5428

Foamex
4011 W Clarendon Ave
Phoenix, AZ 85019
(602) 233-0528

Glacier-Cor
4300 N Miller Rd #243
Scottsdale, AZ 85251
(480) 947-2128

Highland Products Inc
43 N 48th Ave
Phoenix, AZ 85043
(602) 484-9331

Masters Technology Inc
6610 N 57th Ave
Glendale, AZ 85301
(623) 937-4495

Nesco Manufacturing Inc
1510 W Drake Dr
Tempe, AZ 85283
(480) 756-6675

Phoenix Building Products Inc
1004 E Vista Del Cerro Dr
Tempe, AZ 85281
(480) 317-0588

Preferred Packaging & Contnr
3330 W Cocopah St #1
Phoenix, AZ 85009
(602) 272-2040

Schaumaplast Precision Foam
101 S 30th St
Phoenix, AZ 85034
(602) 275-5524

Southwest Ice Block Inc
501 E Plaza Cir #4
Litchfield Park, AZ 85340
(623) 935-5428

Swd Urethane Co
222 S Date
Mesa, AZ 85210
(480) 969-8413

Tharco
640 S 51st Ave
Phoenix, AZ 85043
(602) 233-1331

United Coatings
2465 S Industrial Park Ave #1
Tempe, AZ 85282
(480) 966-8999

Western Insulfoam Corp
3401 W Cocopah St
Phoenix, AZ 85009
(602) 269-2272

Wincup Holding Inc
7980 W Buckeye Rd
Phoenix, AZ 85043
(623) 936-1791

Steve,
how about tacking some wire mesh screen over the framework first? A roll of the aluminum screen material would be pretty cheap and might provide the added support you need for that thin foam.

tissue and dope sounds like a druggy perve occupation dunnit?

Same here - not made model planes for ages

atb

steve

quote:

---

Originally posted by Viper

quote:

---

Originally posted by stephen_gusterson
I wonder if you can adapt model aircraft techniques.....

they cover the structure with tissue and then use dope (nowt druggy) over it that makes it go tight and firm.

Would be too delecate for your mould, but I wonder if some other tissue type substance could be made to do the same..... I wonder if grp tissue would shrink in the right way if used with aircraft dope......


atb

steve

---

blimey, havent used tissue and dope since i was a kid, nearly allways solarfilm or fiberglass now days oh and the odd brown paper job too

---

Wow Pete, that's a good list. Please don't tell me you googled it! I'd be embarassed. heheh I went to H Depot and didn't see the pink stuff. What department is it in? Not construction materials. At least not in Phoenix, but maybe it's a regional thing.

Jack, do you mean put wire mesh underneath the ribs to hold the foam in place? Not sure what you mean actually. The foam I am thinking about is like long solid blocks.

Why not try to use the stripwood concept as used in yacht construction.
Narrow strips of 1/8 plywood can be glued and stappled to the formers, fill the gaps with wood filler and sand smooth.
Final surface finishing can be done with plaster.
It's a time consuming procedure but it's cheap and gives a strong rigid surface.

Get some polystyrene packing like they use in TV boxes and cut them down. PVA glue them with the flattest side up between the ribs to take up some of the volume and add some rigidity without too much weight, then use the expanding stuff to fill in the rest. The stuff you are looking for is sold by Dow as "extruded styrofoam billets". Type it in google, you should find a supplier.

quote:

---

Originally posted by sgraber
Wow Pete, that's a good list. Please don't tell me you googled it! I'd be embarassed. heheh I went to H Depot and didn't see the pink stuff. What department is it in? Not construction materials. At least not in Phoenix, but maybe it's a regional thing.

---

Pete,

I can see what you're getting at - if I could find my copy of "Glass Fiber Auto Body Construction Simplified" (ISBN: 0966713303) I'd scan one of the diagrams in it which shows exactly that process: ribs, braces, chicken wire, hessian, plaster, death from frustration....sorry, finishing You would use a LOT of plaster and it would be HEAVY and FRAGILE.

Steve, surely you've seen the Televante project? It's linked off Alan B's pages. Although he's abandoned the project now, there's some details of his use of pink foam and plaster finishing materials. The results look quite good. Look in the Body/Buck sections.

Good luck

Dominic

Hey Dominic, I had seen that project (Televante) before and thought it was well documented. Too bad he quit. It would have been nice I think.

PeteF, I need to find someplace locally that receives lots of product in styrofoam packing and then recycles or discards it.

PeteB, Using chicky wire and plaster does not sound like fun to me!

Thanks though guys. This is conversation VERY helpful to formulating my plan of action.

Graber
Graber

quote:

---

Originally posted by sgraber
PeteB, Using chicky wire and plaster does not sound like fun to me!

---

Ah nutsack to all that grief foam, plaster,
MDF, latex,..... bahh humbug, have a decko for some C-flex save yerself lots of grief, or if u want the cheapskate version whats wrong with a single skin of csm easy sand bodyfiller and a couple of tins of durabuild. If yer gonna do it do it right

Slap a coat of PVA Bond on to it (watered down PVA wood adhesive) anything sticks to that.





hmmm - interesting thought there Mark. I am thinking that the Drywall filler will not stick to the thermoformed plastic.... How to get proper adherence then?

Graber

If you use the foam as originally planned, couldn't you then cover it with just fibreglass resin? Have seen this done before and it works.
Pat...

UK readers have something equivalent called

the yellow pages


duh

atb

steve

quote:

---

Originally posted by pbura

quote:

---

Originally posted by sgraber
Wow Pete, that's a good list. Please don't tell me you googled it! I'd be embarassed. heheh I went to H Depot and didn't see the pink stuff. What department is it in? Not construction materials. At least not in Phoenix, but maybe it's a regional thing.

---

Nah, it was from some online Yellow Pages (commercial phone directory for UK readers).

Come to think of it, the pink board has limited usefulness even in my area. I put some under a wood floor on a concrete slab porch once, but can't think of anywhere else I'd use it. May be NFG in AZ because of termites, which are not much of a threat here.

One thought I've had for filling the gaps is to cross-brace between the profiles, staple chicken wire 1/2" below the surface, and fill with plaster. I'd think that this would be very fragile, though (wouldn't dare moving it without many hands), and that you'd only get one shot at making a mold.

---

quote:

---

Originally posted by stephen_gusterson
UK readers have something equivalent called

the yellow pages


duh

---

Steve, maybe I misunderstood the type of foam you are using, but I thought it was rather thin strips that you were going to lay over the outline of your form.

What I had in mind is similar to the method used by some artists to make large scale figures. Wire mesh over a buck, layered with plaster, then formed to shape. Kind of like a stucco house or plaster wall, but with shape. window screen is pliable enough to form but stiff enough to hold a shape.

Not sure if the technique would work, but it's an idea.

the foam we have used was purchased from a company who makes industrial buildings, it is used as insulstion in the roof and wall structures, comes in 8 x 4 sheets. not too expensive cuts and sands very easily. We have sucessfully used this to make the bucks for all the bodywork on our car.

regards

marc

Thanks Marc, that's helpful.

I bought some 2" (5.08cm) 4'x8' styro sheets from the hardware store, But I need to glue them together (stack) to make enough height between my ribs. Any suggestion on adhesives to use for bonding Styro that I can still use a hotwire with?

Graber

Don't you live in the Pheonix area?? I suspect that construction is booming near you. Perhaps you could pull midnight shopping spree for the sheets of foam.

Or if you are honest (like me) you can offer $10 to the framers and they will look the other way.

what about model shops, thought that some models where made from styro foam, i.e plane wings etc. we used sikaflex to bond all the pieces of insulation foam but not sure if this is ok for the foam you are using. After all the hours we have had making our seven type bodywork my hat goes of to you, A project of that size is a lot of work, but it certainly looks like you are going to have a very nice looking car indeed at the end

regards

marc

[Edited on 8/6/04 by marc n]

Well, foam carving is well coming along. Styrofoam adhered between mdf ribs using liquid nails construction adhesive. It eats the foam a little, but cures to a skin fast enough that the bond is acceptable.

I've already decided that I am going to skim the foam with a layer of drywall mud to fill in the really low spots and big gaps between the panels, then skim that with a layer of strand reinforced body filler for hardness, then continue out over top of that with another layer of drywall mud so that I can final shape and sand with ease. Covering that will be Kilz Hifill primer and possibly a final coat of Duratec. But I'll wait for that.

To me, this seems like a fairly efficient and cost effective method.

And speaking of costs. To create the entire front of the car - up to the windshield - I used about $15 worth of foam sheets, about $7 worth of adhesive, $7 of wood for the ribs and .50 cents worth of NiChrome wire.


Foam Front Finished

[Edited on 6/11/04 by sgraber]

Wow!

That is taking shape very quickly!

A bit late now but you could have used predrilled holes in the ribs and used cocktail sticks for fixing the foam in with.

Guess you have it all sussed now though!

Looking good!

Terry

what a fantastic thread, this goes to show the kind of people that are members on here, all willing to stick their idea forward and nobody is beaten down for a bad idea, they are all considered on their merits.

I dont think there is a lot that cant be achieved with the wealth of knowledge and practical solutions available on here.

big pat on the back for everyone i think and an extra big one for Steve for actually taking some of the advice and trying it!

Looking good too Steve

Those are the styrofoam billets I was on about earlier. Are you using gypsum plaster over the top of it? Body filler, bondo I think you call it, would be better but more expensive. The "drywall mud" is easily disturbed if you flex it in any way. It should be o.k. if you are taking the mould from it without removing it though.

This is insperational as I have to build a custom back end for my build and hopefully one piece hood with scoop and rad shroud (hotrod style front end)
Nice hint with the hot wire cutting--how are the fumes??
Dale

Thank you guys. Not a negative comment throughout the thread really... Amazing. Encouraging.

I received several emails from some people experienced in drywall who were concerned about the gypsum based drywall just like yourself Petef. The concensus is that I should mix up a batch of the powdered plaster. It reacts chemically to dry, dries in 1/2 the time (not really an issue when its 105f outside) but more importantly is waterproof and much harder then the stuff I am using. If it weren't over foam, I wouldn't worry about it so much. But there are certainly areas of the body right now that are still eggshell thin and they break with the lightest touch. I think it's almost essential to get a harder coat on there.

The wire cutter does make fumes that are a little irritating. I use a fan to blow them away while I am cutting. From what I have read PolyStyrene (open and closed cell) is not toxic, Polyurethane is supposedly very, very toxic!

I also read Paul Stockleys latest update about making the seats for his LMP. He made a hotwire too. Much, much nicer than mine (as is everything he does) but he used mig welding wire in place of the nichrome wire. Simple and even more convenient for most of us since we now don't even have to leave the building to make the cutter!

[Edited on 6/15/04 by sgraber]

you could staple laging wire to the wood forms if you wanted it wo bond together

Is Plaster of Paris the stuff used for this??

I don't think so. It's a product called Durabond and it's available in the USA in all hardware stores. It's specifically for wall application. It's waterproof after hardened.

Steve

What section of the depot did you get this stuff?

The durabond stuff is great as in its origanal use I have used it for doing arches ect when I renavated the last house. You can lay it up thick to a half inch or more thick and If I remember right it comes in 20,40,and 90 minute formulas. Just remember to get it formed and sanded quick as its a bastard to sand afterwards as its very hard.
Dale