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Best way to attach aluminum?

PostPosted: Tue May 24, 2016 10:59 am
by wgwhitacre
Hi, everyone

I am getting to the point that I need to attach .040 aluminum to the outside of my TD. What is the best way to attach it, in your opinion? I have 2 tubes of the fast-drying Trempro caulking, aluminum trim, and a bunch of butyl tape. I plan to "float" the aluminum (just attach the edges). My questions are:

Is that enough TremPro?
Should I glue on the aluminum first, let it dry, and then attach the trim?
Or, should I attach the trim while the glue is still drying?
Should I cut out the holes for the windows and vent before or after I cut out the aluminum?

On some people’s build journals they use about 500 clamps to hold the on the aluminum while the glue dries. I only own 4 clamps and I don’t want to buy more, if that makes a difference. FYI

Thanks for your help with this.

Bill

Re: Best way to attach aluminum?

PostPosted: Thu May 26, 2016 8:56 am
by Thommyknocker
I'm right behind you, so I'll be watching this thread.

I'd imagine you'd have to trim out the doors before the final attachment of the skin, but I may be wrong

Also, If you use the "mix" to seal the wood, does the glue still stick?

Re: Best way to attach aluminum?

PostPosted: Thu May 26, 2016 12:28 pm
by jandbsteardrop
wgwhitacre wrote:Hi, everyone

I am getting to the point that I need to attach .040 aluminum to the outside of my TD. What is the best way to attach it, in your opinion? I have 2 tubes of the fast-drying Trempro caulking, aluminum trim, and a bunch of butyl tape. I plan to "float" the aluminum (just attach the edges). My questions are:

Is that enough TremPro?
Should I glue on the aluminum first, let it dry, and then attach the trim?
Or, should I attach the trim while the glue is still drying?
Should I cut out the holes for the windows and vent before or after I cut out the aluminum?

On some people’s build journals they use about 500 clamps to hold the on the aluminum while the glue dries. I only own 4 clamps and I don’t want to buy more, if that makes a difference. FYI

Thanks for your help with this.

Bill


Hey Bill,

Great question. I literally just finished this step and am not so happy with the results....mainly because my aluminum got a little bent...so it's not entirely flat against the sides...most people won't notice but it's killing me. This is a super important step so do not cut any corners!

I basically did the same thing you are doing....trempro, aluminum, clamps. The first thing that I would do different - get as many hands on deck as possible. My wife and I did this alone...(the sides) while we had three people help with the top and that turned out amazing. The difference with the top vs. the sides is that you have gravity working in your favor on the top....where the sides are just floating there. It's tough to get the sides totally flat with no air pockets.

Your two tubes of trempro will be enough. I used 1 1/2 to do the edges of the top and both sides, around the doors and the vent and a porthole that I have in one of the sides.

We ended up beading around the edge and door and then we set the aluminum on a board that was used to make the side even with the bottom of our side wall...this helped a lot. We then clamped the bottom edge with 2x4's across the entire bottom and then worked our way up, attaching the top with tape. You're really going to need to get more clamps though. Clamps around the door opening, clamps on the bottom, clamps near your hatch and tape for the rest of the way.

Yes, cut your doors and anything else out ahead of time. The best thing to do (in my opinion) is to hold the aluminum skin up and trace the outline with a sharpie from the back side and then set down on saw horses (make sure it's supported) and then use a jig saw with a fine tooth metal cutting blade to get it "close" and then go for it. We then let the trempro dry for 48 hours. It's super strong. After that, I used a bottom bearing router bit (flush trim) and the edges are perfect.

We're going to tackle the trimp and butyl tape this weekend.

Hope this helps!

Jack

Re: Best way to attach aluminum?

PostPosted: Thu May 26, 2016 2:02 pm
by GuitarPhotog
Many here advocate not gluing the aluminum to the sides/top at all. Just attach it with the trim at the edges so it floats over the plywood. Remember that the aluminum will expand much more in the heat than will the underlying plywood, causing it to lift off the ply when it gets hot. Attaching it at the edges only avoids the "oil canning" and plywood distortion that results.

Search this very forum (Skinning Secrets) for suggestions on how to avoid this messy and sometimes costly mistake.

<Chas>
:beer:

Re: Best way to attach aluminum?

PostPosted: Sat May 28, 2016 5:07 pm
by Alpine1
I'm skinning mine this weekend, and my choice is to float it between the trim, then again I live in Arizona where oil canning can be a real problem. I've heard of using carpet glue to establish a quick hold while getting the trim in place then overtime said glue breaking down and "releasing" it's hold on the aluminum allowing full float.

Re: Best way to attach aluminum?

PostPosted: Tue Jun 07, 2016 4:11 am
by ArtMini
I've already used an oil based primer/sealer on the wood of my trailer. My original plan was to paint but there was a lot of water damage to the wood from being under a tarp for so long. I did my best to sand the damaged wood but I've found some spots of primer lifting forcing me to re-sand + paint some spots. Can I still use the aluminum over this? What is TremPro and where do I find it? My trailer is 5'W x 9.5L so it would be difficult to clamp. Also I don't have a lot of help to do this? What do I use as trim around the edges to secure it? I was hoping to do the sides first and then let the top overlap the sides for a better seal? This project has been a disaster and I just want it done. I'm open to any suggestions.

Re: Best way to attach aluminum?

PostPosted: Tue Jun 07, 2016 9:24 am
by Thommyknocker

Re: Best way to attach aluminum?

PostPosted: Wed Jun 08, 2016 11:00 am
by SSTear
I Just finished this step on my first build. I Floated the skin. The roof skin was really tough until I figured how to stretch it a bit in the hot sun with vice grip clamps just to nail down the edges with sst nails. Then I attached the trim and hurricane hinge with Butyl tape and SST screws to seal the edges. Insert the black vinyl extrusion cover. I left .050 gap and slid the galley hatch skin under the hurricane hinge flange. I used the same vice grip clamps to pull the skin up tight under the flange into the butyl tape. I left extra tabs on the alum sheet to clamp tight to the alum so I could get a good grip to pull on. I later cut off the tabs with my Bosch elec. uni-sheer. A tool I couldn't live without. I swear by it.




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Re: Best way to attach aluminum?

PostPosted: Wed Jun 08, 2016 7:16 pm
by ArtMini


That Butyl tape is what we used to use to seal van windows + roof vents back in the 70's+80's. It's kind of a putty that will compact when screwed down.

If I'm understanding you correctly the aluminum just sits on the wood and is held down with the trim? So I can finish priming the wood, and lay the aluminum over it. Then use a trim to hold it down.

So here's what I'm thinking: The aluminum comes 104" wide. I need to by 40', cut in half 20' x 2. My trailer is 61" wide x 114" long x 66" high. So if I cut the first 20' piece of 104" down the middle to 57" and use each piece on the sides from the bottom up. Then take the 104" and run it from the bottom front up over the roof and down to the back bottom. This will create one continues piece with no chance of leaking. Then split the left over 43" wrapping it over the sides to reach the bottom side pieces. This should allow for a 12" overlap on the sides. I can trim that less if I want or just leave it. NOW, to seal the edges I was thinking of using a flat piece of aluminum strip maybe 1"-1+1/2" wide by 1/8" thick with some kind of sealer under it. Which I think the Butyl will work perfectly. I can hold this down with pan head screws every maybe 6" to 9". So a strip along the connection between the roof + sides, a strip along the bottom, and maybe 2 strips from front to back about 6" in from the edges. This will keep the roof/front/back held down flat. What do you think?

Re: Best way to attach aluminum?

PostPosted: Fri Jul 15, 2016 12:45 pm
by wgwhitacre
FYI. I ended up floating the aluminum. Worked great in the desert heat. No oil canning.