Technical Glassing metal louvers into fiberglass!

Hey Guy's
I have a question that maybe you can help me with? I have a friend that has a louver press and he can make me some louvered panel inserts for glass bucket body! How could you mount them so they are flush with the fiberglass with out a hump when you glass them in?

 

Put a flange on them and mount them from the back side? Then just a tiny bit of filling/finishing on the top.

 

That is, if you want them functional.

 

Carefully mark where you want them cut your holes out leaving a lip around each louver panel. Grind the surface of the lipwhere they'll sit down approximately 2x the thickness of the sheetmetal. Use 3M or LordFusor panel bonding adhesive as directed and clamp them in/on the body as evenly as possible.....body work as usual once its set up.

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This...this is correct.

You could use a bead roller or make yourself a set to flange pliers, make a recessed flange in the perimeter of the sheet after the louvers are cut, then fiberglass it from the inside.

Here are a couple of picts from the internet. I'm no help as far as what adhesive to use though so check out what those other guys posted.

 

You can actually buy a flanging tool that goes in an air chisel pretty cheap too. We have one here that gets passed around whenever anyone needs one.

Not to sound negative but it sounds backward to me to put metal louvers in a glass piece. Most of my life I have heard of people putting glass pieces into metal.

 

Porknbeaner, any chance that you happen to have a picture or a quick internet link to the flanging tool that goes into an air chisel?

 

google air flange punch.



https://www.harborfreight.com/air-p...MIop-imobm3wIVgjppCh2_zg20EAQYASABEgLgWvD_BwE

 

Something to keep in mind is that when metal is joined with fiberglass the two materials will pretty near always part ways eventually.
The bond will crack and cracks will appear in the paint and finished bodywork.

Why ? A number of reasons, flexing is one, another is the different reaction of the two materials to changes in temperature, like sitting in the sun and then moving into the cooling down of the evening.

Fiberglass and metal have different coefficients of thermal expansion. These differences almost invariably lead to the failure of such bonds.

I don't know how many times I've looked at fiberglass hood scoops bonded and body worked to metal hoods and saw the cracks in the filler.

 

I used some stuff called 8115

 

The one we use looks like this.

If you don't already own an air chisel the one that @Smokeybear posted may be a better deal for ya. You can buy them like the one her posted electric too.

 

I bought one like @Smokeybear posted from HF years ago and it has been a real time saver. Plus if you note it has a hole punch that makes plug welding panels together or riveting so easy. Ever tool box should have one.

And X2 on @Blue One post. I have tried panel adhesive, plus rivets, plus gorilla hair...nothing will keep it from cracking that I know of.

If you have come up with a miracle cure, post it up here and edumacate us.

 

modern panel adhesive may work especially if it is flanged. It is pliable. I think it was invented for cars that a combination of ABS and metal.

 

A buddy of mine, glassed in a glass scoop on his mustang hood and it held fine, tell he ran it into the back of a dump truck.

 

LOL I had a Chevelle that had a tear drop on the hood. Sold it to a guy who went right out and plowed into the back of a pickup with a step bumper. The tear drop popped off intact. Can't say that the fenders and hood faired so well.

 

Have him make a louvred piece of metal, make a fiberglass mould off that, and put that over a hole cut in the car parts to make fiberglass louvres on your fiberglass parts.

As mentioned, fiberglass and steel joined together will separate at the joints eventually. 5 weeks, 5 years, 50 years, it WILL happen, you just don't know when.

 

Actually one metal panel attached to the back side of the structure would work better I think.

 

Hmmmm...... KahunaKat, I didn't think about the different expansion rates of the two different materials between metal and fiberglass, but yeah, that makes total sense. These guys speak from experience. I've never done much with fiberglass other than a few fiberglass fenders which I never needed to join the two separate materials.

I can tell you that I bought a aftermarket 40 Ford style steering wheel and it cracked after the 2nd year due to the different expansion rates of the plastic vs the inner steel in the Oklahoma summer heat.

Knowing that info, Id suggest mechanically fastening the louvered panel and using a stainless steel decorative trim ring with stainless button head fasteners to make the edges look clean and neat.

Perhaps something like these pictures.

 

Maybe attach with rivets first?
Might help it last a little longer.

 

Rivets will actually make it crack faster due to the difference in the rate of expansion, panel bond works as well as you can get with materials available today.

 

Which is to say that it still doesn't work very well.

 

Pull a mold off of a louvered sheet metal panel, make them from fiberglass and graft them in. If you don't have the materials or know how, have a fiberglass shop do it for you.

 

Exactly. This is something that is not all that hard to do. It is just something that most folks haven't tried.

There are videos on Youtube, and even old-school books on how to do this.

Even I have done it, fixing Corvettes. If can do it, anyone can.

 

Before I worked with building fiberglass boats etc. such a job would have seemed very hard. Today I think it's messy, time consuming, but not hard at all - basically a copy/paste operation.

 

Yup. I was right there too, but young, stupid, and determined.

Once I did it, I wondered what the big deal was all about. Sure, it can get messy, but that can be contained.

 

the best thing to do would be to make a metal tailgate and louver that. that's what I would do anyways

 

I've posted this same response many times but it bares repeating.
I built an 1/8" aluminum trunk riser for my Wescott fiberglass bodied roadster and intended on bolting it in with some kind of sealer, instead decided it would get body finished on the underneath side also.
I had no clue what to use for adhesive so called Karl Wescott for some tips, first word out his mouth was "methacrylate", the only sure thing for getting dissimilar materials to stay adhered together.
In my research I found there are a number of brands on the market and most offer formulations for various material combinations and environments.
Plexus is the brand that I plan on using, it's made by Devcon, to my knowledge
most of these are a two part adhesive and require a special applicator gun, not cheap though, especially if only needed one time.

https://itwperformancepolymers.com/products/plexus

Considering the thin material thickness that the OP is using and the low chance of flex, any of the single part adhesives should work fine.

 

No technical help here, but Bob McNulty bonded louvered aluminum panels into to his Vette in the Fifties, and they have remained to this day.

 

I glassed a steel Brookville vent assembly into my car. I cut the assembly down to a workable piece and then tiged studs to it. The body was thick enough that I could step it down into the cowl area. Used bonding adhesive and mounted it in the body and pulled it down with the studs. Then I glassed over it to level it up with the rest of the cowl. Time will tell I guess..... D

 

Got a router? Skim cut the flange area of the fiberglass where the panel will sit, creat a recess in the face of the glass. Might have to build a little fixture to let the router base sit above that feature line as you work.