Details on "sandwich" construction method

[R Keller]

OK, now I'll try to resurrect this thread. Sorry for the delayed response. Some rather, um, interesting computer problems at home sidetracked me...

Larry, you're right: if you aren't obsessed with weight, it tends to add up quickly and somewhat unexpectedly! Even if you are obsessed, like I was, it still adds up. Of course, I made some design decisions in the name of aesthetics or function that outweighed, so to speak, the weight concerns.

I didn't weigh the screws (!), but I did weigh each panel after I epoxied it together. On of these days, I'll add all of the pieces up in my spreadsheet. Based on where I was close to the end, I think I managed to get the whole thing under 1,000 lbs. dry weight.

Not sure why you'd be opposed to cutting holes in 3/4" ply though. The lumber for framing probably costs more than a plywood sheet. Plus, you could use the cut-outs for all sorts of things. I went the 1x2 framing route like you because I had mostly straight lines, but for the front curve and for the door radii, I spliced in some 3/4" plywood. If you are doing a curved profile, it's a lot easier to do it out of plywood.

Scott: give McBeath a call in Berkeley. They don't list a lot of stuff in the website that they carry.

Capitol Plywood in Sacto carries a lot of good stuff. They only sell wholesale, but you can go there and ask to "browse" and then pay a retailer and pick up at Capitol. Hughes Hardwoods (retail) in Rancho Cordova has a good selection of plywood, including Baltic Birch in all sorts of thicknesses. Also, you can get lumber custom milled there cheaper (and more accurately) than the off-the shelf stuff at one of those big orange stores.

You could do a two-step process to make the sandwich. But, I found that the coat of epoxy on the foam and framing, after inserting the foam, was easy and quick. The part that took the longest was applying the thickened epoxy to all the separate "openings" in the frame.

Hope this helps! If you are in the Sacto area and want to see my trailer or discuss stuff, let me know.

Rik

[asianflava]

OK Guys, I think I've decided to abort my vacuum bagging plan. There are a few things that contributed to this decision.

1 Since I'm doing all the work myself; I don't think I'll be able to coat all 4 sides, align the pieces, seal the bag, start the vac, and fix leaks before the epoxy sets up. The temp still in the mid 80's here.

2 I thought I found a bag big enough. It was listed as a tube but when I e-mailed them they told me that it was a flat sheet. Too much area to seal.

3 Opinions and experiences expressed here and by others. Bagging these wall panels will add unessary complexity and expense to this project.

The guy at West Marine gave me a booklet when I bought the epoxy (West System). They have specific instructions on bonding. It sounds very similar to the process Rik used. I bought microfibers to thicken the epoxy and the notched squeegee.
http://www.westsystem.com/webpages/userinfo/manual/index.htm#2.2

I will play with bagging, on smaller pieces. I found a cool website that has a lot of information on vacuum bagging or rather, "vacuum veneering". http://www.joewoodworker.com/veneering/welcome.htm I have some pieces of 1/2in honeycomb nomex core that I can play with. I also bought a thickness planer so that I can plane the stringers to the thickness of the core material. Maybe I'll use them for galley parts.

[muir]

Hey Rik...

Thanks for the insights on local plywood suppliers.

I may just take you up on your offer of a visit at some point. I'm still juggling some other projects, but perhaps later this winter...

-Scott

[R Keller]

Scott:

No problem. Just send me an e-mail via this site or look up my e-mail address(es) on my website.

Rik