Laminated SIPs?

[Mark Mckeeman]

Short answer,

Because a proper mold for a production TD would cost as much as $30,000. Fiberglass is a petroleum product that fluctuates with the world price of oil. I was roughly quoted $15 per square foot of 1/8 inch thick chopped glass blown into a mold. Add the surface area up and you get one expensive TD. The possible shapes and contours of fiberglass are nearly unlimited however the more complex the shape the more difficult it is to insulate.

There have been many attempts at FG TD's in the past. There are at least two other members of this board that are experimenting with it. One has posted pictures of a mold on this forum.

I think that once the grass roots community makes TD's popular enough for the mainstream fiberglass manufacturers to take notice one of them will mass produce a FG TD. It will be expensive and thus probably find limited acceptance.

There is a manufacturer on the net currently however I’m don’t think they have built many so far. Check out http://www.pull-toy.com/home.htm

Regards, Mark

[GPW]

Oh Master !!! Let me tell you a story about an Artist and a Sculptor , who have made molds for everything in the past , including molds for CF parts on motorcycles... Just finished a mold of Father Seelos(The Saint )... Molds are expensive if you have someone else make them ... the Padre's mold cost 36bucks (US)... I could mold an 8' TD for under 5oo bucks and be RTM...any business requires an investment .... the current thinking is . If you can't make a killing very quickly in a new business, why bother ??? But I know many many people who have made a comfortable living from their enterprises... and don't have to pay some insensitive "bean counter" to tell them how to screw the last teardrop of profit from any situation ... This TD buss. thing is all Theoretical , of course ...

I have a friend in the go can business (Portable toilets ) .. he buys these molded beauties for about 400 bucks each (in quantity )... nice plastic about 4'x4'x8' with a door and plumbing .... how cheap is that ...

to me there could be nothing more hideous than a TD made outta' a go- can , but it's the thought ...
we "HANDY" guys would never consider a mass produced TD, prefering to express ourselves in our constructions... Glorious Diversity !!!!! But , there are guys out there that would love to have a TD , but can't do anything involving TOOLS without hurting themselves or others (you know a few, I'm sure) They are the guys dropping 5 Large on a TD....In that case some type of SIP/ molded panel/whatever system would work ,and be practical in a large run ..if you had the market ...

No offense to anyone , OK !!!

[Mark Mckeeman]

GPW,

You are correct! and no offence taken.

I've spent a year researching the feasibility of a FG TD. Yes, to contract the mould making out would cost big bucks. Therefore the only option is to build it myself. Perhaps I have over thought the whole process as my idea would require several molds, one for the top, one for the floor, one for the hatch one for each door and yet another for the galley bulkhead.

All this doesn't explain the lack of success for those who have gone before. There is no evidence that I can find of a FG TD that has enjoyed a long production run. A few have come and gone. They were mostly of a squarish Benroy type design, I suspect for mould making simplicity.

I have a feeling that the design was the problem. These square designs failed to capture the classic Teardrop style and failed to take full advantage of the ability to produce more complex shapes out of fiberglass. For this reason I assume that they didn't capture the imagination of the public and failed to enjoy long term success. Just my theory.

For success I think you need a TD that is just as cool as the Hotrod towing it. If these auto enthusiast don't mind investing 30-50 thousand bucks into a car then they may think 5-10 thousand for a TD is reasonable. Another theory.

At this point have I not decided to pursue a production FG TD. I'm just not sure of the market, and I have never attempted anything like this before so I'm very cautious. Maybe if I could find a few other individuals that would be willing to assist in mould making, then produce one for each of the partners at reasonable cost you could get a few on the road to generate interest and explore the market. Yet another theory.

I'm very good at theories but very poor on the follow through.

[GPW]

Mark , You're right on !!! The looks are everything .... if someone did a really cool rounded Star Wars looking TD and marketed them right , I'll bet they'd do well.... Nice molded in fenders ,scoops , al the cool stuff (molded storage like an airliner )...stylish , like a "vette"... The traditional TD was most excellent for our grandfathers... straight parts were easy to reproduce at home (as we are now doing ) , but it's time to put the cards on the table and design some really cool /innovative TD 's....so who has 50 large to set up a business making TD 's... bet they'd be more popular then a FEMA trailer . eh ???here anyway ... hahahaha

[captainsam]

Please note not all ureathane SIPs are made the Thermacore way, in fact, Thermacore is the exception, not the rule.

Guy

I stand corrected. Further research shows that pre-formed sheets of both polyisocyanurate and polyurethane are bonded to surface facings (OSB) to make SIPS of home building.

I was confused because while these materials can be foamed "in place" between the facings using the foam itself as the bonding agent, the polystyrene SIPS ( EPS and XPS) can ONLY be made by "glueing" the panels to a foam blank.

For some reason I thought that was the only way it was done. Obviously the poyurethane based adhesives could just as easily bond the panels to a poyurethane foam core too. I would suspect the process is probably cheaper and simpler but I can't imagine why the Thermacore process would be used if that is the case... unless it's structually superior in some way.

Thanks

Sam

[Guy]

Dear Capt,

I visited Thermacore about a year ago on one of my trips back from the East Coast. They use HUGE, HEAVY steel sheets as weights between the layers of the panels they are making. They are the only manufacturer that actually cuts the windows and doors out first, then frames them, and then put in the conduit, all BEFORE they pour the foam. It is an extraordinary operation, real tidy, all in one building. Their method adds great value for the architect, builder/owner. However, if you were to ask them how they would do a teardrop panel, they will tell you to use foam sheets if you are a one off or even two. It is exactly what they told me and I have built two SIP houses already.

BTW, another thing Thermacore does that is great for SIP buildings is the connecting system for achoring panels to each are poured at the same time. No foam cutting or work on the job site. Just lift those babies up, level em, screw em and put in the windows and doors.

The ISOGRIP and ISOSET are great products, and I do not hesitate to suggest them. If you look at the whole previous thread, I posted a simple way to make panels from sheet foam, including ureathane.

[captainsam]

Dear Capt,
If you look at the whole previous thread, I posted a simple way to make panels from sheet foam, including ureathane.

Great info. Being a new guy, I missed that thread. Any help finding it?

Sam

[Guy]

Dear Capt.,

Here is a link to one of the many previous discussion threads re: SIPs

http://www.tnttt.com/viewtopic.php?t=1926&start=0&postdays=0&postorder=asc&highlight=ashland

[captainsam]

Dear Capt.,

Here is a link to one of the many previous discussion threads re: SIPs

http://www.tnttt.com/viewtopic.php?t=1926&start=0&postdays=0&postorder=asc&highlight=ashland

Good info Guy!

Last night I tried the following, motivated by the thread I had just read.

I took a couple small scraps ( 3" X 24") of 5.2mm luan panel and cut a similar size of 1.5" thick DOW blueboard (Extruded Polystyrene or XPS). I moistened one face of each plywood with a damp rag. I lightlty ran some 120 grit sand paper once over both sides of the blueboard to roughen the surface and I wiped the faces off with the damp rag. I buttered both sides of the blueboard with a thin layer of Gorilla Glue (polyurethane based) and made a sandwich between the damp faces of luan. I clamped and went to bed.

This morning I unclamped and wow! That son of a gun is strong. I span about 18" between two chairs and stand on it with one foot. Hardly any deflection. I don't know how it could bond much better,

Now.... am I missing something or is it really that easy to build a composite panel? I had been experimenting with pouring the foam but this seems equally as strong, and less messy. The glue is expensive but maybe it can be purchased in larger quantities cheaper.

I will try the same experiment with beadboard (white expanded polystyrene - cheaper) and see how well it works. Also HD had a pink XPS 2" foam board (FomulaR) for less than half the blueboard price so I may try that too.

I figure a 4' X 8' panel would cost $22 for two sheets luan, $ 12 for the foam board, and $8 for glue. Thats $ 42 per panel.

Still thinking about Guy's swimming pool clamping idea. Water weighs 62 lbs, per cubic foot so that means a 1 inch square column of water 1 foot high exerts (62/144=0.43) 0.43 psi pressure. For even 2 psi it would take 5 feet of water. Assuming you built a rectangular "pool" overlapping the 4 x 8 panel sides by a foot in all directions, that would be a 6 X 10 pool 5 feet deep or 300 cu feet. That is 2244 gallons of water. It would take a long time to fill that with a home water tap. So we need another plan. Now Honda makes a 5.5 HP gas powered pump with a 3" hose and a transfer rate of 275 gallons per minute that you can probably rent. That is just over eight minutes to "load" the water. I guess you would need another "pool" to hold the water as it has to be ready to go when you need it. Maybe you could make one panel with a first pool and then transfer the water to the other pool to make another when the first is done. My neighbors are going to love this!

I think vacuum bagging may be a better solution. I have been told a good shop vac bas deliver 3 psi of suction, that's the about same pressure as a 7 foot column ( "pool") of water. Now...but if we could fill the pool with mercury... no just kidding.

Where am I going with this composite panel stuff? How about a Weekender type design made of composite panels that are joined by both edge glueing and using epoxy fiberglass on the inside and outside of the joints.

I think composite panels make sense as the side panels of a tear too.

Any comments?

[madjack]

I like the vacum baggin idea...we have a cheap shop vac but also have a Dyson...wonder how much suction that Dyson will pull and will the wife(aka the poor girl) let me use it hmmmmmmmmmmmmmmmmmmm
madjack

[captainsam]

I like the vacum baggin idea...we have a cheap shop vac but also have a Dyson...wonder how much suction that Dyson will pull and will the wife(aka the poor girl) let me use it hmmmmmmmmmmmmmmmmmmm
madjack

I looked and must shop-vac products have between 55 and 61 inches sealed pressure. The height it can lift a column of water.... just what we were taking about earlier.... how deep the pool would have to be.

[angib]

I like the vacum baggin idea...we have a cheap shop vac but also have a Dyson...wonder how much suction that Dyson will pull

No need to wonder about that, madjack - chances are, that Dyson will have broken down before you get that far along......

Andrew

[Guy]

Dear Capt.

Regardless of clamps, vacuum, or water. The main issue is that the pressure MUST be equal across the whole panel. Simple Clamps do not do that, Vacuum does, as does water. Capt., the HUGE steel plate that Thermacore uses is making sure that pressure is exerted evenly so there is not chance for delflection on the surface, even though it also exerts a tremendous amount of pressure. The structural integrity of a SIP is measured at its weakest point.

The reason for the water pool notion in the previous thread was because the point of that thread was how to do it as INEXPENSIVELY as possible. I certainly agree with you that vacumm wouldbe better but it would not be as inexpensive.

BTW, you are not missing something when you calculate the price. About a year and a half ago, Jamie at Happitrails felt his price was somewhere in the 1 dollar per square foot range.

[captainsam]

Dear Capt,

BTW, you are not missing something when you calculate the price. About a year and a half ago, Jamie at Happitrails felt his price was somewhere in the 1 dollar per square foot range.

As a newbie I don't have the advantage of what has gone on here before... does Jamie make or buy his panels for $1 per square foot? If he buys them, where? What are the facings and cores he uses?

Here are few photo's of my latest tinkering:

About 3" X 20" X 2" thick

5.2mm Exterior Luan and 1.5" Dow XPS (Blueboard)



Made with Gorilla Glue



Bending but not breaking

[Guy]

Dear Capt.
\

Great work on that SIP.


Jamie made his own SIPs.just like you.

In order to make curved SIP you will have to use a type of foam that Curves with heat, or pour your own into molds. Using jigs such as those used in the plywood bending industry which maintain equal pressure across the entire surface so there is no deflection or dimensional variation. BUT you are certainly doing well.