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(09-15-2019, 02:19 PM)maki2 Wrote: [ -> ]By the way....VHB tape develops strength over time. Trying to figure out if it is strong enough by immediately pulling on it after you apply will never be an accurate test of its true strength as it has not had sufficient time to develop its full strength.

I don't know of any adhesives that have full strength immediately after application. I use a lot of various adhesives and they all state a full cure time rating of a week or more. Some of course will give you a shorter time for more immediate use but if you read carefully the length of time for a full cure is longer than that.

Because I have a work background in manufacturing I have to read directions very carefully so I know how to apply the adhesive, what it is rated for and how long it takes to develop strength.  Some persons will do that when they work with adhesives but others just read the front of the package and then go for it.  But when you have hundreds of dollars invested in something such as solar panels and when it is a critical safety issue that the stay put when you are out on the road you need to take the time to truly understand what is going to give you the results you need to have. 

I have a painted roof on my trailer, it is good paint but I don't trust it not to have localized failure so I won't be using VHB tape on its own for the installation. I also have a  fiberglass roof so on the interior I will install blocking and then thru bolt my solar panel brackets to secure them. Screws thru just the fiberglass would not give adequate strength, the fiberglass is not thick enough for screw holding under the load forces that will be put on the panels when underway on the road.
That’s where stainless steel rivets come in play.
(09-15-2019, 02:02 PM)maki2 Wrote: [ -> ]I am guessing you did not realize that there are 7 different "families" of 3M VHB tape. Each family has particular characteristics which make it more suitable for various applications. For instance some bond better to painted surfaces and some bond better to plastic or aluminum and some can be used in higher temperature applications. 3M VHB is a broad category and if you got the wrong family of tape for your needs then you could very well have a failure in your application. Not only that but sometimes you need to purchase one of the specialized adhesive bonding promoters that need to be brushed onto the surfaces before the tape is applied.

We all know that surface prep has to be done according to the instructions. If you don't do it correctly you can have adhesive failure. The adhesive that fails might be the VHB or it might be the paint adhesion on the van which has failed.

Part of choosing the right tape is doing the background research on the 3M website to find out which family of tape is best suited to your needs. Then of course doing the prep work which might include applying an appropriate bonding promoter. Another factor which is essential in deciding if you will be able to use VHB tape is the amount of surface area on the brackets themselves. The VHB tape is rated for strength based on the number of square inches of surface. So each bracket must meet the specifications for the load ratings that are stated for each of the different families of 3M VHB tape. That means you must do some engineering calculations based on your own unique applications of the tape and also the size of the brackets as well as the wind speeds and resulting forces of pounds of pull on your panels. Another major issue with using VHB tape on vans is many of the vans have paint that peels easily and gets damaged by the UV rays. The paint adhesion will fail and since the VHB tape is stuck to the paint the problem is not a tape adhesion failure it is a paint adhesion failure. I would say that on any of the older vans you either need to repaint the area where the brackets will be installed and then give the paint several weeks time to cure or else just go ahead and use mechanical fasteners to install the brackets.

Yes, I think mechanical fasteners are a simple and effective method for installing solar panels. No need to complicate things with such products as VHB tape.
Did you happen to watch Tito’s video on flexible solar panel installation?

https://youtu.be/hROYaqY83v4
(09-15-2019, 10:28 PM)Weldman Wrote: [ -> ]That’s where stainless steel rivets come in play.
Not really because stainless steel rivets will over time enlarge the hole in the fiberglass. I have seen that happen to several people who own fiberglass trailers, it was true of the Sunrader fiberglass motorhome I used to own, it leaked at lots of rivet locations, I had to replace all of them. and I have seen even more people posting about that issue on the fiberglass trailer forums.

I don't use any rivets to install things thru the fiberglass hull for that reason. I have installed blocking behind all the fittings that go thru the shell. The fittings are better supported and easier to remove if needed.

I am actually not a clueless newbie who does not know how to do stuff. I do know how to rivet, I used to do it for a living and have put in a  thousands of rivets and other types of pull fasteners over the years. I was a lead mechanic at Boeing. I do have a pneumatic rivet puller and stainless rivets but I won't be using rivets to install my solar brackets. They will be bolted in place with backing plates on the interior to further distribute the load over a wider area.

The cabinet framing I fabricated to put into my build is aluminum and I fastened it together with rivets although is secured to the walls with screws into blocking, but at the base bolted thru the floor.
Just a small sample area of the aluminum cabinetry, this area  has a pull out drawer for my fridge. All my own custom work except for the full extension slides.
[attachment=24468]
(09-16-2019, 12:51 AM)LoupGarou Wrote: [ -> ]Did you happen to watch Tito’s video on flexible solar panel installation?

https://youtu.be/hROYaqY83v4

I'm watching it now. ThanksSmile
No experienced DIYer ever recommends to use VHB just on a standard bracket. If you want to mount something on your roof without drillng holes, the trick is to bolt the brackets to another piece with a much larger surface area, and then VHB or glue that down. Try attaching two 4" x 4" steel plates together and then pulling them apart. Try a 6' piece of extruded aluminum VHBed down to a perfectly flat roof. That ain't going anywhere.

On 3M's web site, there are videos about a trailer company that uses only VHB to fasten the side panels and corner protectors in place. But that is a very large surface area.

Nails hold entire houses together. But you can pull apart two boards held together by a single nail with your bare hands. I guess nails shouldn't be used to build houses.
If someone decides to use VHB tape on their RV or van to mount solar panels, they should from then on, avoid using truck washes.

Many commercial truck washes use acids, not mild soaps or detergents like would be used at your local car wash. Acids like hydrofluoric acid, phosphoric acid, and sulfuric acid are some of the ones in use at some commercial truck washes.

These acids are capable of weakening or dissolving the VHB tape and/or its adhesives.
(09-16-2019, 01:08 PM)LoveCareThinkD Wrote: [ -> ]... a trailer company that uses only VHB to fasten the side panels and corner protectors in place. But that is a very large surface area.
That type of mount is called "ABS Solar Panel Mounting Bracket".  They will only work on flat roofs such as you might find on some motorhomes and on some cargo trailers or step vans.  They have more surface contact area than an typical metal solar mounting bracket has.  But they only work on truly flat roofs. Step vans often have flat roofs, so do some motorhomes, box trucks, some cargo trailers. But on many vans the roofs are curved rather than being flat all the way across.
(09-16-2019, 01:08 PM)LoveCareThinkDo Wrote: [ -> ]No experienced DIYer ever recommends to use VHB just on a standard bracket. If you want to mount something on your roof without drillng holes, the trick is to bolt the brackets to another piece with a much larger surface area, and then VHB or glue that down. Try attaching two 4" x 4" steel plates together and then pulling them apart. Try a 6' piece of extruded aluminum VHBed down to a perfectly flat roof. That ain't going anywhere.

On 3M's web site, there are videos about a trailer company that uses only VHB to fasten the side panels and corner protectors in place. But that is a very large surface area.

Nails hold entire houses together. But you can pull apart two boards held together by a single nail with your bare hands. I guess nails shouldn't be used to build houses.

perhaps folks might want to revisit what 3M, the manufacture has to say about how big a surface area of vhb tape should be used. hint, they say dont do it

https://www.cheaprvliving.com/forums/showthread.php?tid=37319&pid=457380#pid457380

arm chair quarter backs can fiddle and postulate. but when a 50 pound solar panel comes off a roof at 65mph, people can die. are you will to kill the driver behind you to prove the manufacturer is wrong?
(09-16-2019, 02:08 AM)maki2 Wrote: [ -> ]Not really because stainless steel rivets will over time enlarge the hole in the fiberglass. I have seen that happen to several people who own fiberglass trailers, it was true of the Sunrader fiberglass motorhome I used to own, it leaked at lots of rivet locations, I had to replace all of them. and I have seen even more people posting about that issue on the fiberglass trailer forums.

I don't use any rivets to install things thru the fiberglass hull for that reason. I have installed blocking behind all the fittings that go thru the shell. The fittings are better supported and easier to remove if needed.

I am actually not a clueless newbie who does not know how to do stuff. I do know how to rivet, I used to do it for a living and have put in a  thousands of rivets and other types of pull fasteners over the years. I was a lead mechanic at Boeing. I do have a pneumatic rivet puller and stainless rivets but I won't be using rivets to install my solar brackets. They will be bolted in place with backing plates on the interior to further distribute the load over a wider area.

The cabinet framing I fabricated to put into my build is aluminum and I fastened it together with rivets although is secured to the walls with screws into blocking, but at the base bolted thru the floor.
Just a small sample area of the aluminum cabinetry, this area  has a pull out drawer for my fridge. All my own custom work except for the full extension slides.
My apologies I forgot to add in the use of 5200 too when you do to prevent movement. Seen the enlarged holes too even after the backing. Never said you were a clueless newbie or anything in that fashion.
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