bgordon's 5 week cardboard & fiberglass build

[glassice]

Being as dry as it is there using card board is great way to help with the heat
It look like you have been doing this forever

[bgordon]

Hi all,

My apologies for not answering sooner. I was busy with something else, and my Internet took a back seat.

Cliff, thanks for that Condor photo. It's really something!

... then a foam/resin/glass cloth shell should be like a tank.

Yep! To prove my point, I took a photo with me on top of the trailer. I weigh almost 100kg (220 pounds), and I think I could easily have doubled the weight on the trailer.


I also want to clear up a misconception. I did NOT use a chopper gun. I have never even seen one! I simply used chop strand fabric, and painted polyester resin (after activating it with MEKP of course) on the fabric.









I used general purpose polyester resin.

who are ready to tout the advantages of epoxy and how BRITTLE resin is?

No. Polyester resin, in itself, is brittle. But it is the fiberglass fabric that gives it it's immense strength.

Now, question for the fiberglass experts who are mentioning using foam- won't polyester resin disolve foam?

As mentioned by others, polystyrene will not work with polyester resin, but POLYURETHANE foam will (with a few exceptions). For example, the polyurethane filler foam works like a charm with polyester resin. Here we can buy the rigid polyurethane foam in 4 foot by 8 foot sheets. But it is a real MESS to work with. Far worse than fiberglass and resin!

Oh, and other question, how is strand fiberglass like that applied? Put into resin and smoothed on,or what?

Very simple. Cut the chopped strand mat with a pair of scissors to size (like cutting material), and place it on the cardboard. Mix the resin, and pour it on the fabric, and wet out the fabric with a roller like this one. It's almost like painting a wall with a roller.

I believe the fellow used a "chopper gun" to lay his glass.

No. I used polyester resin, applied with a roller, and chopped strand mat 'fabric'.

Fiberglass isn’t a resin. The resin is the matrix material that keeps all of the fibers in place so that they can react the load. The matrix itself can be either polyester or epoxy (or a few other things). Either will work and each has advantages. Polyester is cheap; epoxy is not. Epoxy is higher strength and more stable and is used in the aerospace industry along with high-performance marine applications whereas Polyester is mostly used in lower-cost marine applications (think recreational boating).

Kenny is right. The strength lies in the fiberglass fibers. The resin simply holds it in place. Resin in itself is brittle, and using it without fiberglass fibers makes NO SENSE WHATSOEVER. However, together it is immensely strong. As a matter of fact, fiberglass is per weight as strong as steel.

By the way, almost all recreational vehicles use polyester resin and chopped strand mat. The same goes for boats that traverse the oceans. Epoxy and woven fiberglass fabrics are used in aerospace industry, as Kenny explained.

So, as Gus states you have to use a ‘real’ structural foam.

I am not an engineer, but as I understand it, the internal foam/cardboard/whatever-is-inside-the-core is simply there to keep the two fiberglass layers apart. And apparently it does not need to be really strong. This explains why one can use lightweight foam, etc.

One thing that should be noted for chopped fiber (the kind you spray on to save labor). It isn’t as strong so you need more of it. It’s not that the chopped fiber won’t work; it’s that the fibers are shorter so the weaker resin is doing more of the work and so more chopped fiber is required to carry the same load. More chopped fiber also means more resin to hold it so the overall weight goes up. As has been discussed several times before, the teardrop loads are not that high, so it’s not a big issue – as far as strength is concerned.

Yep. 100% correct. And the strength lies in the fibers, and NOT the resin (be it polyester or epoxy). That's why you'll notice in fiberglass aircraft videos that the builders use as little resin as possible. The motto is 'resin adds weight, fiberglass mat adds strength'.

The easiest way to duplicate the cardboard build with a ‘structural’ material [rather than the cardboard] would be to use the Home Depot/Lowes foam and layup fiberglass and epoxy fabric over it…

Yep. Or use polyester resin (MUCH cheaper) with any POLYURETHANE foam (NOT polystyrene!). The cans of filler foam comes to mind. Or use something else like MDF/supawood, masonite, or whatever...

[By the way - using fiberglass and resin (polyester or epoxy) with a natural product, like plywood, is NOT recommended. God really knew what He was doing when He made wood. It will crack even fiberglass if it collects water (just like roots of trees crack emmense boulders in nature).]

It would probably be a lot faster to spray on the fiberglass. but without taking time to build a mold, the exterior would look all rough like chopped fiber and thus would have to be sanded a BUNCH to make it look smooth (if that were important to you).

Actually, you add body filler before you start sanding. I used almost 20kg of body filler on the trailer, although you sand most of it away...

And let me tell you. that's the worst part. Sanding, and sanding, and sanding.....

It look like you have been doing this forever

Wow, glassice, coming from you it's a great compliment (seeing you have your own fiberglass shop). Thanks!

[glassice]

don't fell bad that you did not use a chopper gun there $14,000 Us are so
and anyone that done glass and not justs reading a book knows that hand laid is liter and 2 times are more stronger than a chopper
I think your looks better than the one we sell

[pete42]

First I have to say "CUTE KIDS".
Then building a teardrop using mat fiberglass must have been very hard to do.
I built two fiberglass airplanes Burt Rutans Veri-eze
we used foam cores with two types of fiberglass one was BI-DIRECTIONAL and one was single directional they both came as rolls of fiberglass
we built a large table, workbench covered with smooth panelling. The foam like your cardboard is only used for the shape we wanted it does not add any strength.
The BI-Dir. 'glass was used on the wings cut on a bias so there was bending strength and compression strength. I stood on the front wing which was sitting on buckets at each end I too weighted around 220 lbs.
we tried to get the cloth as dry as possible with out getting it to dry epoxy only adds weight. using fiberglass on a roll made it very easy to cut and form over the foam.
We used 1 inch paint brushes to "stipple" the epoxy into the cloth then a squggee and finally a roller like you used.
with a good paint job your trailer should last long enought you will be able to pass it down to your kids. It will never collect water inside the panels.
all I can say great job.
yes we are lucky living where we do there is a fiberglass specialty house not 20 miles away. By the way we carved our planes from 4 foot squard by 8 foot long foam blocks using a hot wire and templates.
PETE

[steve smoot]

Barry, you really did an excellent job. that camper looks as nice, if not better than a lot of factory units. Wish you lived next door...

Steve

[mezmo]

Hi Barrie,

What an inspirational build ! You'll have a lot of people
thinking about and seriously considering the fiber glass
composite building method now. Strength, low weight and
no wood rot are serious considerations. The cardboard core
is such an intriguing idea for the composite core. Your
efforts really have paid off - proven by your successful
family trip.

You mentioned that you were working on a folding trailer
design. Have you made any progress? I looked through
your album and noticed some pics of the ZA Off Road
trailers that I find quite interesting. I came across them
while searching on the web. The Jurgens Safari,
the Imagine and the Conqueror ranges all contain great
ideas for maximizing minimal camping. I wonder if any
of those manufacturers ever considered exporting them?
I have a feeling though that high cost is probably a factor
with them.

Again, congrats on this build and best luck on the future builds!

mezmo/Norm

[bgordon]

don't fell bad that you did not use a chopper gun there $14,000 Us

Wow! I didn't know they were THAT expensive!

First I have to say "CUTE KIDS"

Thanks! I think so too!

Then building a teardrop using mat fiberglass must have been very hard to do. I built two fiberglass airplanes Burt Rutans Veri-eze

Wow. TWO aeroplanes! My brother built an aeroplane. It took him many, many years. I think there are only a few things in life to build that is harder than an aeroplane. And you built two!

I think building my teardrop was a walk in the park compared to your aeroplanes!

The foam like your cardboard is only used for the shape we wanted it does not add any strength.

That is the amazing thing for me. The core material does not need to be strong at all, and yet the overall product is immensely strong.

Wish you lived next door...

Me too, but only if I could live next to you (in the USA) and not you living next to me (in South Africa). Yes, I am kidding somewhat. I love the country I live in, but if I look at all the amazing products you get all around you, I can only drool.....

You mentioned that you were working on a folding trailer design. Have you made any progress?

Norm, well, somewhat. I decided to build the folding trailer out of fiberglass, due to the fact that it is much more durable in the elements. Wood rots, and steel rusts (and aluminium is simply too expensive!). But the problem with fiberglass is that it does NOT like sharp bends. getting the panels to fold properly AND making them round AND weatherproof, is quite a challenge. And it is not working out as yet.

In the meantime I have decided to enjoy the small trailer. My wife initially thought that the tiny trailer would simply be too small for the four of us, but she is now the one that wants to go camping even more! And spring is slowly approaching, so I think the tiny trailer will be used more than I had initially anticipated (I built the trailer for our long camping holiday only, and thought I would scrap it after that trip).

My small children will easily fit into the trailer for the next two or three years, but by then I have no doubt that another, even better trailer will stand in my driveway!

I looked through
your album and noticed some pics of the ZA Off Road
trailers that I find quite interesting. I came across them
while searching on the web. The Jurgens Safari,
the Imagine and the Conqueror ranges all contain great
ideas for maximizing minimal camping. I wonder if any
of those manufacturers ever considered exporting them?
I have a feeling though that high cost is probably a factor
with them.

As far as I know the Jurgens safari range is exported to Australia. The Imagine trailvan is fairly popular here, but the factory is small, and I think the owner is battling to keep up with local demand.

Conqueror exports to the US (they have in the past anyway). I have seen some of their trailers on e-bay and Craigslist, although they are fairly scarce.

Oh, a young'n here told me how to pronounce South Africa like you natives. "Suta-freeka"....is that correct?

Woodstramp, I realized I did not answer you. Yes, you are quite right. I would say more like "Soo-iet Uf-reeka" (for the Afrikaans spelling of "Suid-Afrika").

(And of course, if your name is Sep Blatter from Fifa (soccer), you'll say "Soes Efrieka")

If you have a house - you have a hobby.

Boy, are you right! That is what will be keeping me busy in the following months (and keeps me from my next build).

[michaelwpayton]

Hey now - throw the yellow flag! time out. What's this about fiberglass resin? Where are all the epoxy folks (and you know who you are) who are ready to tout the advantages of epoxy and how BRITTLE resin is? surely this thing is going to fall apart because he used resin instead of the better and more expensve epoxy! enough of the rant - dude that is some well laid glass work and an excellent concept of materials.

STARLEEN2,

I can't speak for others that you may be referring to as "epoxy folks," but the concerns I have posted in other threads relating to the use of polyester resin have all been with respect to its use with plywood. Please... try to understand... the fact that epoxy resin is superior to polyester resin when used in conjunction with plywood... has nothing to do with what this builder has accomplished here with polyester resin.

[IASCOTT]

Barnie did you install any hard points where you install the hinge screws for the doors and the hatch. Also the mounting points to the trailer frame.

Scott

[bgordon]

Barnie did you install any hard points where you install the hinge screws for the doors and the hatch. Also the mounting points to the trailer frame.Scott

Yes. Although fiberglass is very strong, it is also quite soft (it performs better in tension than compression - similar to steel). Anyway, I used pieces of steel flat bar in the door where I attached the hinges, as well as with the hatch and mounting points to the frame.

BaRRie (not BaRNie)

[starleen2]

Hey now - throw the yellow flag! time out. What's this about fiberglass resin? Where are all the epoxy folks (and you know who you are) who are ready to tout the advantages of epoxy and how BRITTLE resin is? surely this thing is going to fall apart because he used resin instead of the better and more expensve epoxy! enough of the rant - dude that is some well laid glass work and an excellent concept of materials.

STARLEEN2,

I can't speak for others that you may be referring to as "epoxy folks," but the concerns I have posted in other threads relating to the use of polyester resin have all been with respect to its use with plywood. Please... try to understand... the fact that epoxy resin is superior to polyester resin when used in conjunction with plywood... has nothing to do with what this builder has accomplished here with polyester resin.

Duely noted - But I will be a resin guy. I think that fact that this guy did use resin instead of epoxy shows that resin can be used successfully. That is what i wanted to highlight for those who are reading this. I find it hypocritical that those who use epoxy exclusively do not want to challenge a builder who uses it exclusively in their build and it worked out just fine. This builder demonstrates that. I say Kudos to his reasourefulness and to doing something innovative. BYW how's the Benroy coming along?

[eamarquardt]

Hey now - throw the yellow flag! time out. What's this about fiberglass resin? Where are all the epoxy folks (and you know who you are) who are ready to tout the advantages of epoxy and how BRITTLE resin is? surely this thing is going to fall apart because he used resin instead of the better and more expensve epoxy! enough of the rant - dude that is some well laid glass work and an excellent concept of materials.

STARLEEN2,

I can't speak for others that you may be referring to as "epoxy folks," but the concerns I have posted in other threads relating to the use of polyester resin have all been with respect to its use with plywood. Please... try to understand... the fact that epoxy resin is superior to polyester resin when used in conjunction with plywood... has nothing to do with what this builder has accomplished here with polyester resin.

Duely noted - But I will be a resin guy. I think that fact that this guy did use resin instead of epoxy shows that resin can be used successfully. That is what i wanted to highlight for those who are reading this. I find it hypocritical that those who use epoxy exclusively do not want to challenge a builder who uses it exclusively in their build and it worked out just fine. This builder demonstrates that. I say Kudos to his reasourefulness and to doing something innovative. BYW how's the Benroy coming along?

I don't see why it's necessary to quibble, bicker, or otherwise argue supporting the merits of polyester resin versus epoxy resin given that virtually all FRP boats (including blue water boats) are made out of the stuff and some of the first boats (Glasspar and Columbia) are still going strong. Like all materials both epoxy and polyester resins have strenghts and weaknesses and it up to the user to make the "right" choice. Perhaps polyester resins are lacking "self esteem".

Cheers,

Gus

[parnold]

I hope the "resin wars" posts stop as they are detracting from an awesome build thread!

[michaelwpayton]

I hope the "resin wars" posts stop as they are detracting from an awesome build thread!

Sincerely sorry that my posts may have been/are distracting. No worries... I'm done.

[skuntz]

Great build and it has helped to bouy a number of conceptual ideas that I've had.

Question... does anyone know of a Canadian (Ontario specific) supplier of cardboard products such as the 6mm cardboard in this build??