Laminated SIPs?

[GPW]

The Cap'n is certainly on to something here , and a simple vacuum bagging setUP would work even on larger panels .. without exotic eqpt. ( a vacuum cleaner unfortunately won't work ) Even simple bagging will increase clamping pressure ALOT !!!! Our bags were made of plastic and rope caulk =SIMPLE !!!
Seems like building the framework, foam and skins(Plus the inner and outer finish product )glued together, then bagging , would produce a ready to use panel ...a few screws and some glue ... DONE !!! and you could make it very light ...as we used to make light fiberglass/balsa wood / foam wings ... strong and they FLEW!!!

[Guy]

Dear Sam,

Another low tech solution for clamping follows.

Just for laughs.

If you built a series of simple wood I-beams connected by a plywood panel on top. Then used one of those inexpensive car ramps to get the front wheels of your car on top of the I beams the ramp would spead the load over the I-Beams, and the I-beams would spread the load over the panel.

[captainsam]

Dear Sam,

Another low tech solution for clamping follows.

Just for laughs.

If you built a series of simple wood I-beams connected by a plywood panel on top. Then used one of those inexpensive car ramps to get the front wheels of your car on top of the I beams the ramp would spead the load over the I-Beams, and the I-beams would spread the load over the panel.

Guy

You say "just for laughs" but ideas like these have been whirling around in my head for a couple weeks now. I figure a 1 ton p/u truck rear axle would have about 4000# spread over 32 sq ft is 0.87 psi. I still like the dunnage bag idea but even at 3 psi the frame requires double 2 X 6 cross beams spaced on 1 ft centers above and below the panel stack. That's about 18 - 12' 2X6 boards just to build the frame. And then you have to store it when not using it. I did think that if I had a crawl space under my house, maybe I could put the dunnage bag and the panels between the floor and the ground. Unfortunately, the 10 tons of lift would probably lift the floor of the house off the foundation. I keep returning to vacuum bagging as the answer just as GPW says above. I saw plans on how to build a vacuum pump system that is designed for large veneer projects. You can see it at http://www.joewoodworker.com/veneering/welcome.htm It would cost about the same as the dunnage bag idea, but could be used to make curved panels and is small to store when not in use. For that matter I could UPS the pump to other teardrop builders to borrow... no way with the dunnage bag press. I think with the right glue and careful surface prep of the facings and core material that 3psi is plenty of pressure to build a high quality panel. Of course with vacuum bagging the sky's the limit...literally.

Sam

[GPW]

and with the Vacuum bag , you can slobber epoxy all over the outside of the panel and it'll end up like glass... Nice !!!

[GregB]

Sam,

Any difference between the PL Premium Construction adhesive and their PL 300 foam board adhesive which seems to be made specifically for bonding foam boards with skins?

GB

[captainsam]

Sam,

Any difference between the PL Premium Construction adhesive and their PL 300 foam board adhesive which seems to be made specifically for bonding foam boards with skins?

GB

The PL Premium is a Polyurethane based adhesive. 30 minutes working time and a initial set time of less than 8 hours.

The PL 300 is a rubber/resin based adhesive. 20 minutes working time and 24 hours initial set time.

The tech rep seemed to think that the polyurethane was far better for structural applications.

Sam

[Guy]

Dear Sam,

Great site on vacuum bagging, it is amazing for 1800 psi.. And superb posts on your conversations with the tech reps.

[ARKPAT]

Thank you very much Sam for the information and the site you linked to. Also the to the pump and mold links inside the original site. Super information and "How-To". Now I have some of the needed information I was thinking about. Now the possible design that are available and how to mold the panel up helps.



Thanks very much,
Pat

[Artificer]

Sam,

I asked a professor (Agricultural enginering/Ag
Structures) here on campus about glue for a truss beam I'm fixing. He said the PL polyurethane glue was the best due to cold temp curing, no outgassing (no foaming) and the gap filling capability. Its what you found out from the tech, but another endorsement.

I meant to post about your question of the vacuum bagging frame someone had. I haven't seen a response, so this is my idea about it. Your question was something along the lines of: what holds the side frames from colapsing into the panel? Without seeing the setup, I can envision the box being air tight, with the vinyl cover. You drop whatever part you want clamped into the box, put the vinyl cover on, and draw a vacuum. The vinyl doesn't span the box, but rather follows the contours of the box, until it comes to the part to be clamped. Its sort of like the vacuum forming machines.

Well... that description was clear as mud. If you have questions, I'll draw a diagram when I get a chance.

Would you be interested in a vacuum pump to continue your experiments? I've got a few of various quality that I've salvaged if you're interested.

[GPW]

Imagine, if you will, a large sheet of plastic , folded over in half ... sticky rope caulk forms the outer 3 sides turning it into an airtight bag .... part/panel is in the bag , vacuum line goes into the bag too ,... more caulk/seal ....Vac is turned on , bag collapses around the panel exerting great pressure... like a giant Foodsaver...eh ?

[captainsam]

Imagine, if you will, a large sheet of plastic , folded over in half ... sticky rope caulk forms the outer 3 sides turning it into an airtight bag .... part/panel is in the bag , vacuum line goes into the bag too ,... more caulk/seal ....Vac is turned on , bag collapses around the panel exerting great pressure... like a giant Foodsaver...eh ?

I have read of polyurethane and vinyl bagging materials. Will common polyethelene sheeting work? It is readily available for use as a vapor barrior in home construction in 4 and 6 mil thickness. Will this work?

I saw a heated rolling poly sealing tool designed to seal packing bags. It made a 9mm sealing edge by melting (welding) the plastic together. I wondered if this tool might be an easier than the caulk you mention? What exactly is this "rope caulk"? Would silicone caulk work to seal the three sides that don't have to be reopened to insert a new panel to vacuum?

Some of the references talk about a "breather" fabric used to provide a path for the vacuum to get to all parts of the bag. One online source showed a platen used used for this purpose on flat items. It is placed above the panel and has shallow evenly spaced parallel grooves cut on the top both length wise and across the panel. The idea is that even if the bag gets pulled tightly against the platen, the grooves provide a good path for the vacuum to get to all parts of the bag.

I'm trying trying to figure out a way to do this cheaply as possible, otherwise why not just buy the panels ready made. I appreciate any ideas you have.

[Chris C]

I've kept my nose out of this thread, until now because the word ecomical came into play. I make my living working with wood. Ocassionally I have to apply veneer to a large surface such as a desk or diningroom table top. The key word there is "ocassionally". If I did a lot of it, I'd build the vacuum system shown on this site: http://www.joewoodworker.com/catalog/vacuum_press.php But I don't do enough of it to warrant the expense. That's why I pay a shop that does this for me................with a vacuum bag system. The last desktop I had laminated cost me $52! If I were going to build SIP walls on my teardrop, I'd cut out the parts and take it to a shop that could do perform that process. Cheaper than all that running around buying materials to make a system you probably won't ever use again. Just go to the Yellow Pages in your area and look up wood shops that do veneering.

[captainsam]

Sam,

I asked a professor (Agricultural enginering/Ag
Structures) here on campus about glue for a truss beam I'm fixing. He said the PL polyurethane glue was the best due to cold temp curing, no outgassing (no foaming) and the gap filling capability. Its what you found out from the tech, but another endorsement.

The only advantage I can see with some of the other adhesives is tha shorter cure time that a vacuum would have to be maintained. I assume that the bag does loose some vacuum over time requiring some cycling of the pump occasionally. I like the PL Premium since it is readily available at HD & Lowes at a reasonable price.

I meant to post about your question of the vacuum bagging frame someone had. I haven't seen a response, so this is my idea about it. Your question was something along the lines of: what holds the side frames from colapsing into the panel? Without seeing the setup, I can envision the box being air tight, with the vinyl cover. You drop whatever part you want clamped into the box, put the vinyl cover on, and draw a vacuum. The vinyl doesn't span the box, but rather follows the contours of the box, until it comes to the part to be clamped. Its sort of like the vacuum forming machines.

I see what you mean. I did learn from my test panels that you need a frame around the panel stack to hold them in alignment during clamping. The glue is slippery and they tend to slide. I just cut some strips of melamine faced board to place around all edges and then tightened a ratchet strap around the panel edge perimeter. It seemed to hold things well and was easy to remove after the panel was done. It may be just as easy to put a few long screws through the stack to hold the alignment until the panel is done and then remove later.

Would you be interested in a vacuum pump to continue your experiments? I've got a few of various quality that I've salvaged if you're interested

What do you have? I read I need a 3 CFM pump to make a 4' X 8' flat panel. A curved panel would need more CFM. I'm interested.

Sam

[asianflava]

Imagine, if you will, a large sheet of plastic , folded over in half ... sticky rope caulk forms the outer 3 sides turning it into an airtight bag .... part/panel is in the bag , vacuum line goes into the bag too ,... more caulk/seal ....Vac is turned on , bag collapses around the panel exerting great pressure... like a giant Foodsaver...eh ?

That was my plan when I originally thought I was gonna bag my walls. One problem I found is that this method lacks a caul for the piece to conform to. In other words, since it isn't being held down to a flat plane, it chould bow up and cure that way. I suppose you could put some weights on it to prevent it from curling up.

The main reason I ditched the idea was because I didn't think I'd be able to seal the bag and suck it down before the epoxy started to set off. I needed more working experience with the epoxy. Now that I've worked with the epoxy, I think I could do it by myself if the weather isn't too hot.

[GPW]

rope caulk?... we used some stuff from the auto parts store , came on a large flat roll , used to stick down windshields ...nasty sticky stuff ... we used regular plastic sheeting from the HD , 10 mils I think(check for holes) ... never used a breather ... pro stuff , we were Cheap stuff , used what we had ...worked fine for all manner of wings, really large and small (model stuff ) ... TD parts would be larger and easier , cause we had to put the wings in outer cauls , then turn on on the vacuum ...TD stuff is stiff already , and the vacuum won't distort it ...a few well placed brads keeps everything from shifting , and I believe TD panels would have a frame all around , to join to the panels , right ???
I think Chris is on to us ??? more money than it's worth , unless we're starting a business, eh ?