Any ideas for attaching expanded metal to aluminum skin?

belfert · July 01, 2012, 07:13:34 AM

My luggage bay doors are aluminum skin over an aluminum frame. I want to cut some holes in the aluminum skin of one of the doors to vent that bay. How can I attach aluminum expanded metal to the back of the skin? I'm pretty sure welding would distort the skin that is perhaps 1/16" thick.

Stormcloud · July 01, 2012, 07:21:02 AM

Press the piece of mesh into a copious bead on Sikaflex which you careful placed around the hole.

belfert · July 01, 2012, 07:34:12 AM

Thanks for the great suggestion. Now I just have to search through the archives for the best place to get a tube of Sikaflex.

rv_safetyman · July 01, 2012, 08:13:16 AM

Brian, the other option is to rivet the expanded metal using longer rivets and washers behind the EM.

I will be interested to see what you choose for the EM. I have to replace the EM on my passenger side rear door that lets air into the CAC. Had to cut holes in the stock part when I used 12V fans. Expanded metal can have some pretty good blockage if your choose the wrong type. In your case, it is probably not a big deal, but it is really important on my application.

BTW, I am going to be really disappointed if you don't have a panic thread before you leave

Jim

belfert · July 01, 2012, 08:27:40 AM

I'm kinda hoping to avoid having any fasteners going through the luggage door if possible. I was thinking about small stainless carriage bolts if I didn't get a better answer. The expanded metal I'm looking at is like this: http://www.amazon.com/Aluminum-Expanded-Diamond-Openings-Length/dp/B003SLEXSS It is available in different sizes and thicknesses for more or less air flow. I'm going to see what the local metal dealer has available Monday or Tuesday.

I have a luggage bay that is actually the place where the condenser was so it has a vented door and a vented floor. I put the generator in there. In a former life a driver had hit something and dented the door. Whoever fixed it did a bad job and the door barely closes. I was able to pick up several solid luggage bay doors cheap and I am going to cut holes in one and install the expanded metal to cover the holes. I think 58% percent opening will be more than the original vented door and the generator is fine with the venting from the original door.

belfert · July 01, 2012, 08:52:46 AM

Quote from: Stormcloud on July 01, 2012, 07:21:02 AM
Press the piece of mesh into a copious bead on Sikaflex which you careful placed around the hole.

Am I really going to need the cleaner and primer for this project? The cleaner and primer are way more expensive than the 252 itself. Interestingly enough Camping World carries Sikaflex 252, but not sure I want to drive 60 miles round trip to get it there. There is one other local place I am going to check with.

I tried to order the 252 from Ellsworth Adhesive, but they require a $50 minimum.

Gordie Allen · July 01, 2012, 09:04:48 AM

I bought 10 tubes of Sikaflex to put down my floor. First 10 tube delivered we so hard, even 120# air caulk gun couldn't push it out. I called the dealer, they sent me 10 more. Same issue. Went back to polyurethane liquid nails. Half the price and just as good IMO. Just wipe down with acetone or lacquer thinner - also much cheaper.

Boomer · July 01, 2012, 09:48:51 AM

Or you could remove panel and have it lazer cut to any pattern you like, louvers, screen, etc.

belfert · July 01, 2012, 09:57:42 AM

Quote from: Boomer on July 01, 2012, 09:48:51 AM
Or you could remove panel and have it lazer cut to any pattern you like, louvers, screen, etc.

My first idea was to get the holes cut in the door with a laser or water jet, but I realized I have no idea where to get this done and I figured it would cost a lot more than doing it myself.

Could I get this done for $75 or less? I wouldn't even know where to start to look for a place to do this. The panel can't be removed from the frame of the door as it is bent over the frame and bonded with adhesive or high strength tape.

A buddy of mine used to operate a laser, but I don't think he could have done this since it isn't just a flat sheet of metal.

Stormcloud · July 01, 2012, 10:10:21 AM

I have used a Canadian equivalent of Sikaflex with no primer or cleaner, and it's still holding after 5+ years. Just make sure the metal is clean and dry when applying adhesive. ( I used lots of BrakeKleen to clean the metals before joining).

I had to get a tube of Sikaflex in Arizona this past winter, and the guy at the windshield shop where I bought it suggested that it be WARMED before it is applied. Either leave it in the sun for quite a while, warm carefully in an oven (200F), or immerse it in a tub of hot water ( and keep replacing the water with more hot ). After about an hour of heating it flows much easier, and can be worked with a manual caulking gun.

Boomer · July 01, 2012, 10:43:58 AM

If you screen it, wire cloth works better than expanded metal and comes in all patterns. I used SS wire cloth for rad and A/C doors on my Silverside. It is much smoother, expanded metal is sharp.

Jeremy · July 01, 2012, 10:49:28 AM

I know I'm not answering the original question, but my approach to this would be to use off-the-shelf vents that are available for this kind of thing, rather than trying to fabricate a vent from scratch. As it happens I've already bought some vents for the generator door on my bus. The chandler I went to had vents in all sorts of different styles, including some which were almost identical to some OEM vents already on my bus (the lower of the two black plastic types in the bottom photo; I've included the other two photos as they are probably more similar to what you're trying to create)

Jeremy

happycamperbrat · July 01, 2012, 11:38:24 AM

Just throwing my 2 cents in. Liquid Nails "anything" is not good for long outside in the desert heat..... it always fails quickly here after a couple summers outside in the HOT. I havent tried Silkflex for anything yet, so cant speak for that stuff.

belfert · July 01, 2012, 12:47:51 PM

Here are a picture of the original vented door and a picture of the replacement door. I got the replacement door from Raines Bus Lines in Golconda, Illinois along with a few more doors for spares as they are no longer available new. Raines did not have any good vented doors left. The one or two he had left had all been damaged like mine. Ken and Ruth got the last good vented door from him for their Dina.

Each vented area is about 10" tall and 19" long although the bottom two areas along the bottom are several inches taller. What I want is to have about the same amount of ventilation when I am done as I have now. I thought about cutting bigger slots in the door by hand, but that thought lasted about 30 seconds.

bevans6 · July 01, 2012, 02:14:46 PM

If you use an epoxy type agent (sikaflex, etc) then preparing the aluminium panels you are gluing to (the back side of the doors in this case) is important. For best results you need to get the oxidization off, which means physically abrading the surface no more than 30 minutes before you apply the glue, and use 60 - 80 grit abrasive to create a tooth for the glue to bite on to. I use a fresh disc on a little angle grinder with the little sanding pad attachment. I think the glue is a good idea, but I would stick to a two part epoxy type. That will stay stable at pretty high temps, it takes around 300 degrees to get it to release.

Brian