Fastening stuff to fiberglass ?

[Hopper]

How do most of you fasten hooks or lightweight shelves to fiberglass shell ? Certain epoxy like 3M marine epoxy?

[theresa p]

Hi Carla----Actually, I got some excellent responses under my thread in the General Chat forum titled "attaching awning rail".

The concensus leaned heavily to 3M VHB tape. I have used this product before, in the interior actually, but not yet on the exterior. However, those who replied give it top marks.

The biggest choice with it seems to be actually picking which of their VHB product line best suits your desired use.

And in the interior, I am lucky (I think of it as lucky, though others may disagree!) that my camper is lined with ratfur. Inside, I use the hooked Velcro to adhere anything I need and it works well. Sometimes when I am removing things, the ratfur kind of needs a trim afterwards to keep the long fibres that had stuck to the Velcro from looking funky. But that takes just seconds with a pair of scissors.
And also inside, I have used that same 3M VHB tape. I had applied it to some lightweight wooden letters, spelling RELAX, which I stood up on a ledge right below the back window and they have been there, without moving at all, for 12 years now. I'd say that is excellent adhesion!

Command hooks of any type also work well on the interior fibreglass and wood, if you have any. Many options with them, depending on your need.

Hope that helps some.

[John in Michigan]

We've used command strips with great success. Even used just plain command strips to hold a stainless steel paper towel holder to interior gel coat. Key is make sure the surface is super clean and dry.

[Hopper]

Great information, Thanks everyone.

[Jon in AZ]

Depends on where, inside or outside, how much weight it needs to support, and whether you want it to be removable.

Command hooks are great to attach to the fiberglass cabinets inside because they can be removed without a trace if you later want to change it up.

The shell itself is completely covered on the inside with headliner. Very light things can be attached with the hook part of Velcro.

For something heavier you could slit the lining and epoxy a block of wood to the fiberglass to create an attachment point. The object itself could be removed, but the block would always be there.

Outside... VHB tape, rivets, stainless steel screws.

Tell us what you want to attach and where.

[Hopper]

I love you guys ! You have all in inside info. I want to attach some wire shelves.
They are light weight. I have been told not to screw into the fiberglass. I get that but I can use a small screw , tape around the place I want the screw and drill in reverse with pressure. Is any of this correct? I think drilling with a diamond drill bit forward slowly will be alright, yes? Please let me hear your personal knowledge, it really does make a difference from people that know.

[Mike Magee]

Trailers bump and jump and thud and jar as they go down the road. Enough to pop open cupboard doors and refrigerator doors sometimes, for example.

Hmm, wire shelves. I can't imagine velcro on 'rat fur' keeping them up, and I would never drill holes in a Scamp. If the headliner material is the old non-fabric type, maybe the Command Strips or VHB tape would stick well enough to do the job.

[Hopper]

We shall see......

[mccownw]

Rivets are the best for fastening through fiberglass. (Note use of rivets by Scamp for installation of windows, etc.)

[redbarron55]

Pop rivets may be the worst fastener for this , ubiquitous use not withstanding.
Why else would there be so many with so much experience replacing the loose ones?

[Jon in AZ]

Only rivets I've had to replace were because the part they were holding on was rusty or cracked. Coming up on ten years old, zero rivet failures on my Scamp.

That said, rivets require a hole, and I would definitely consider other means of attaching non-essential accessories before I got out my drill.

So... wire shelves. Where? Attached to what?

[gordon2]

Originally Posted by Jon in AZ

Only rivets I've had to replace were because the part they were holding on was rusty or cracked. Coming up on ten years old, zero rivet failures on my Scamp. ...

So I have to ask, what constitutes a failure in a rivet? Is it only a break? What about one that becomes loose and is still holding the item up, but is so loose that a rain water leak occurs?

Many (most?) Scamp rivets go through the bubble insulation and rat-fur, and as that compresses, the rivet is not as tight as it was originally. Right now I am looking at two or three on an upper side cabinet that are loose enough that I can turn the acorn nut, and also pull on it to see about 1/8 inch play. I expect that being this loose, water could get in, run down the inside of the insulation and end up on the floor.

I had another rivet on the side bath wall where it connected to the shell that became loose, causing the wall to separate from the shell, and the caulking there also separated making the shower no longer water tight. When I replaced it, I found the hole in the shell and bathroom wall that the rivet went though was not straight. Is this a rivet failure?

If something cracks, then was the rivet perhaps defective?

Perhaps in some cases we should not be talking about rivet failures, but instead, failure of the rivet technique in the particular application. I suspect that is why Scamp started using bolts in a few selected high-stress areas (such as the large fridge/microwave housing connection to the roof).

[theresa p]

Wire shelves---you ARE adventurous!!

Since I have not needed to affix anything that heavy or potentially that much of a projectile, I'll suffice it to say that from what I've learned thru my own experience plus from the helpful experience of others here is that VHB tape seems like the go-to product. However....wire shelving might just be the limit for it.

Where are you hoping to put said shelving? And what is it that you plan on storing on said shelving? These are important tidbits of info needed to be able to help you out.

[redbarron55]

Pop rivits are prime for cheap, fast assembly and are particularly poor where the expanded body is set in a softer or oversized hole and cannot be drawn up tight and the parts move in relation to each other.
Fiberglass is not particularly suitable for pop rivets, but they are cheap and fast.
Design concerns dictate choices as do economic. If fastened with Stainless steel screws the cost would be a bit higher for hardware and a lot higher for labor.
Compromises are made in every manufacturing operation.
No doubt that the pop rivets are adequate except for working loose every now and then.

[Jon in AZ]

Originally Posted by gordon2

...If something cracks, then was the rivet perhaps defective?...

That's a good question. By "cracked" I meant that some plastic components are severely UV degraded, specifically the fresh water fill spout and the escape hatch cover (which I haven't dealt with). I don't think it had anything to do with the rivets, but of course, replacing them requires replacing rivets.

And so no, no rivet failures- broken, loose, or leaking- and no component failures cause by the rivets.

I only speak from my own experience. I certainly do not question yours, Gordon. I have often wondered whether the 16'ers flex more than the 13'ers, or whether the rush to crank out trailers during the current boom has resulted in sloppy technique. Mine was built at the bottom of the 2008-2009 recession.

[Eggcentric]

To fasten an awning to my tupperware Toyota Sunrader, I through bolted it, and put rtv on the bolt shank to ensure water tight ness.
To afix solar panels to my Sunrader and Boler, I fiberglassed brackets to hold the panels.
To fasten my new shore power and water fill I used pop rivets.
To fasten bulkheads to the hulls of sailboats I used fiberglass.
To fix wood to fiberglass I have used epoxy with good results.
I only use screws in emergency, they tend to chew up the holes and then tear out, although you can screw through the FG into wood with good results.
To fasten the new door lock I through bolted it.
There is no best way, it depends on what you are doing and how well you use the materials.

[Raspy]

Originally Posted by Hopper

I love you guys ! You have all in inside info. I want to attach some wire shelves.
They are light weight. I have been told not to screw into the fiberglass. I get that but I can use a small screw , tape around the place I want the screw and drill in reverse with pressure. Is any of this correct? I think drilling with a diamond drill bit forward slowly will be alright, yes? Please let me hear your personal knowledge, it really does make a difference from people that know.

You don't need a diamond drill to drill through fiberglass. Just a standard drill bit from the hardware store. Drill in reverse? Why? Just drill a hole in the standard way as if you were drilling in wood. Fiberglass is not hard to drill through, but it will dull the drill sooner than drilling in wood, so it's best to get high speed steel or titanium bits. No problem. No reason to overthink it.

Fiberglass does not hold screws well, so you need nuts on the opposite side or a wood block on the opposite side to screw into. You can seal the screw holes with caulking or silicone. Epoxy sticks very well to fiberglass so it's a good way to mount backing blocks or tabs to mount bulheads to. If you plan to screw through from the outside, use stainless screws.

[John in Santa Cruz]

re VHB tape, this is commonly available at hardware stores as '3M Extreme Mounting Tape', such as https://www.amazon.com/Scotch-Extrem.../dp/B005SRECEU

re mounting a wire shelf in a Scamp... is this shelf going to be under an overhead cablnet? how about two vertical metal straps, bent at the top like an angle bracket, and screwed through the bottom of the cabinet (2 screws per strap), and screw your wire shelves to these straps? I'd use stainless screws with stainless washers on the back side of the fiberglass cabinet, and stainless nylock nuts..

[Eggcentric]

Running the drill backwards is done by some in the belief that it warms & softens the plastic to make it easier to drill and less prone to cracking, fiberglass gel coat is not very thermo elastic so even if it did work (doubtful) on ABS, PVC, or LDPE it does not affect fiberglass.

[redbarron55]

The cutting angle of the drill might be changed to not dig in too quickly and crack the fiberglass.
I haven't had a problem with drilling holes in my Scamp.
Drilling plastics with a drill that more scrapes than digs would be indicated in a plastic like plexiglass to reduce the likelihood of cracking.