sciff5

iTrader: (1)

Well I got the structural foam in the mail today. Its a 2 part polyurethane expanding foam. I can tell now after seeing the foam that this may not work out.

I am trying to put the structural foam into the SFCs that are now welded to the bottom of my car, Which requires drilling a hole or several holes in the SFCs and pumping the liquid (before it becomes foam) into the round tubing. Well there seems to be several problems. The first being that it looks like I am going to need quite a bit of foam.. I am going to have to move about a pint of liquid into the tubes, (which is a lot and you'll see why soon) Thats a lot because the 2 part liquid when mixed together starts foaming in under 1 min. On top of that the liquid is more like a gel, its very thick stuff, thus to move approx 1 pint of fluid in under a minute will require a large hose for the liquid to move through the problem with that is that is that I need to now drill a bigger hole in the SFCs, weakening their integrity.

Any POSITIVE ideas or comments would be apprciated at this point.

Kevlo911

iTrader: (36)

My plan was to pour the mixture into caulking tubes and then inject into the holes. Less than 1/2 holes would be needed. I don't have the foam to try my idea but you can.

beancooker

You seem to be rather intelligent, so work with this idea; a LARGE syringe (horse needle type) remove needle and use syringe body, and to the back of the syringe body a chamber that attaches to an air compressor hose to push the gel out. (remove syringe depresser and fill syringe replace depresser and attach air hose , then propel in) but I don't know if it can be done in less than a minute. another idea , a new grease gun

sciff5

iTrader: (1)

Well the problem I see with that is just the time involved in the idea. You would need to measure out the 2 liquid parts evenly then throw them together into a bucket and mix them as much as you possibly could (I guess if you dont really mix the 2 parts together you get gunk instead of foam). Once the 2 parts are touching in a mixing bucket you've only got 45 seconds to get the liquid where it needs to go before it starts to become foam. You would need to vigerously mix the 2 parts together, dump them into caulking tubes, and than use a caulk gun to inject the stuff into the crevas all within 45 seconds or it will start the foaming process on you prematurly. Of course the other big thing is whatever pump and or hose you use to get the foam into the tube will be useless after its first use cause it will be filled with hardened foam.

This is the best idea I've come up with so far. I bought a pump originally that I was planning on using to pump the gell from a mixing bucket into the SFCs, but I think what I am going to do is use a funnel connected to a hose that runs the length of the SFCs inside them. I am going to use an electric drill to mix the 2 parts as quick as possible and than I am going to pour the mix into the funnel and than once all the gel is out of the funnel and into the hose, and the tubing of the SFC I am going to disconnect the funnel from the hose and connect the pump to the hose and pump air down the hose forcing all the gel/foam out of the hose and into the inside of the tubing of the SFCs. Once all the foam is out of the hose I plan to pull the hose out of the SFCs and stick a cork, or whatever fits, into the hole that I drilled for the hose to plug it and create some pressure as the foam expands, so it expands into all the small crevases of the tubing. I also plan on using more foam than is nessecary for the tubing so it actually pushes the cork out of the hole after it is done expanding the entire volume of the SFCs tubing and drips out onto a bunch of cardboard that I am going to be laying out.

I am prob going to dill the hole as close to the end of the SFCs near the back as I can and put the back end of the car on ramps as I pour the liquid in, to give me some room to move around under there. Once the foam is in and the hole is plugged I'll drive my car off the ramps and let it sit on the ground normally so the foam doesnt harden with the chassis tweaked, just like you wouldent put SFCs on a car that wasnt sitting level.

sciff5

iTrader: (1)

I got an idea on how not to destroy the structural integrity of the tubing yet make a pretty big hole to inject the foam. Check out this picture. As you can see this metal peice up front hangs down from the bottom of the car and the tube connects to it. If I drilled a hole through that metal piece down the middle into the tube it wouldent destroy the strength the tube gets from being a complete cylinder, because I'de be filling the tube through the end of the tube. It is going to be more of a pain in the a$s to drill through cause the tubing should be capped and thats 1/4" stock, but should be better overall.


Needtobefast: thanks for the compliment, I think thats the first time anyone on the board has used the words smart while describing me but the syringe was my first idea, the one I still think would be the best. But remember all syringes would be useless afterwards, and I couldent seem to find a syringe big enough to move the volume of liquid I need to move in such a short period of time. If I could find a huge syringe that would really be the perfect idea. After a few hours of thought I do have an idea that I think, given I dont have equipment failures, should be pretty good.

bigEL

Have you checked with the manufacturer to see if they have slower setting foam? When I used to work with composites, we had a supplier who could formulate the foam to set up anywhere from instantly to >24 hrs. The two parts create foam via a catalytic reaction when mixed together. The more catalyst in the formula, the faster the foam sets.

Hoooper

wouldnt it be ok if it starts foaming while youre injecting the liquid? as long as youre still pumping some in the foam should move toward the end of the tube and you would have a lot more time to comeplete it than you think. if you drill a small hole for air to escape through on the opposite end of the tube the foam will be even more likely to move that direction as there would be very little resistance

irish44j

iTrader: (38)

what about one of the pump tubes used for pumping differential/tranny fluid into feed holes? Those basically suck from a jar or bucket or whatever....

I would also suggest perhaps you get in touch with someone familiar with boatbuilding or boat repair, as those guys typically have a good deal of experience with structural-type foam for framing...

I will also note, for the record, that I still think this is a bad idea - too many downsides (uneven pouring, unfilled areas, possible distortion of the tubing) and no real upside...the tubing should be plenty stiff as it is, especially since you used a high-strength tubing.

I would, instead, use the foam to fill the rocker panels and perhaps some other body areas, rather than filling the SFCs....

sciff5

iTrader: (1)

well tomorrow I am going to try and move the 2 part foam through a 1/2OD 3/8ID vinyl hose. The problem is it is going to move through at least 7-8 feet of hose. I dont know the pysics lesson on why its harder to move the same viscosity liquid through the same diameter hose if the hose is longer, but it is.

One part of the 2 part liquid has the viscosity of corn starch and the other part is probably the viscosity of transmission fluid. So combine the 2 and the combination has a viscosity a little better than maple syrup. Its thick stuff.. I am worried that its so thick it wont even reach the end of the hose to get any into the tube.


I think my chances of making this work would be a lot better if I pumped a lot of the 2 part liquid (much more than is needed to fill the tube) into the middle of the tube (that way I could pump the liquid through half as long of a tube)and let it expand untill it comes out of the only place it can escape which is the hole I drilled to inject it, which will also seal the hole.

NmexMAX

iTrader: (22)

Use a large static mixer if injecting.


Do you need to add any water at all? Any clue what type of foam it is?

(manufacturer, shelf name etc)

There are many different types of foams, some with fast rise times, and some without.

As a precaution be aware of exotherm also.


You'll aslo need a plug.

sciff5

iTrader: (1)

ME VS DA FOAM

Well boys the war has been waged against da foam... I got owned hard core.. Nothing too valuable was destroyed but when I tried to force the foam down into the tube it splattered everywhere. I am pulling it off my skin, thankfully I covered my car before doing this job, but lets see me costs so far

Cost me 30$ for a cone shaped bit to drill the holes in the SFCs
10$ for the vinyl hose
20$ for the foam
10$ in funnels
30$ for the shorts I just ruined with splattered foam

what does it all equal an expensive waste of time... Hopefully my 100$ contributes to knowledge that this foam is VERY thick stuff and will not travel down any sort of hose, it barely went through the bottom of the funnel.

So if you want to pour it into a cavity make sure you drill a BIG hole, and dont plan on pumping it anywhere.

MacGarnicle

iTrader: (1)

Sorry to hear that man... live and learn though.

If you do try to attempt it again, I would, as others have suggested, try to find a foam that requires more time to set.. I'm sure you did your research so maybe that was the only one available?

Plan on trying it again?

nismopc

iTrader: (3)

Why not buy Great Stuff???

For big gaps...
http://greatstuff.dow.com/greatstuff/cons/biggap.htm

For everything else...
http://greatstuff.dow.com/greatstuff/cons/gaps.htm



Has a straw for application and flows at a pretty high rate before foaming up and drying.

SEmy2K2go

iTrader: (10)

I still fail to see the need for this. Seems like a waste of $100 and a lot of time IMO. The SFC's should have done everything needed without added foam in the tubes.

JdoubleOe703

iTrader: (6)

i think u needed some sort of pump like a large injector syringe. ALso the tube you got should have been larger, its easier to move liquid through a larger diameter which then narrows to the size of the hole then to use a tube the same size of the hole...

better luck next time....

irish44j

iTrader: (38)

Great Stuff is insulating foam, not structural foam. It has little to no value in the application we're talking about. It is not high enough density to have any real strength.

Jeff92se

iTrader: (82)

How come you didn't try this?
http://www.sportcompactcarweb.com/pr..._300zx_part_5/

NmexMAX

iTrader: (22)

When you pour foam the last thing you want to do is use a tube.

A static mixer (the type used in some epoxy's @ AutoZone) would have been better, but nothing is better than pouring when dealing with foam...

Some foams have isocyanates... so ahh the skin thing, might not be good...