Custom Extrusions for FRP Panels

[PacificNorthWestJeeper]

Just searched the forum and could not find it so I apologize if I missed it.
Does anyone have a lead on a Company that will make 'one off'/custom extrusions for FRP panels?
Thank you ahead of time...

 

[Victorian]

Just searched the forum and could not find it so I apologize if I missed it.
Does anyone have a lead on a Company that will make 'one off'/custom extrusions for FRP panels?
Thank you ahead of time...

custom? It’s very expensive… you need to engineer it, make dies and then run a minimum length in production ( usually a full container load). We have several custom frp pultrusions in our name and I can tell you it’s not cheap. Think about a $30,000 price tag per design. There is also a lot that could go wrong.. you need to get the mixture of resin/glass dialed in, you also need the fiberglass strands specked correctly to get the needed strength.
in other words: expensive and not cheap to do. Virtually impossible to source in North America.

the benefits of using frp pultrusions are amazing! you avoid thermal transfer, panels and pultrusions expand/ contract the same way ( avoiding stress cracking), way lighter that aluminum and much more.

 

[Peter_n_Margaret]

This is my chosen method.
Add a simple 90 degree aluminium or pulltruded FRP angle to one or both sides. Or even guillo and fold aluminium or hand lay up FRP for odd angles if you are keen.

I have found that there is usually no weight savings to use pulltrusions because the minimum thickness is double and they are much more expensive than aluminium extrusions which can be powder coated befor the build. BUT you need to do a differential expansion calculation if you use aluminium to ensure that the glue thickness is sufficient to accomodate the temperature extremes that you expect to encounter. Longer extrusions = thicker glue joints.
Aluminium is also weldable.


Cheap, effective, lots of choice, no cold connections. Works for all panel thicknesses, including mixed.
My panel supplier in Oz can CNC cut the panels to your design including the edge preparation, if required.
Cheers,
Peter
OKA196 motorhome

 

[Victorian]

Agreed. Tons of different ways to join panels.
our system is designed for simplicity and speed in a production setting . I have build many cabins with solutions shown below and they are very time intense. But at the end ,if time doesn’t matter to you , they all offer great strength.

 

[rruff]

Does anyone have a lead on a Company that will make 'one off'/custom extrusions for FRP panels?

The drawing that Peter showed above is how Styromax joins their panels with no other reinforcement (except for glue). If you buy high strength FRP skins, stainless steel angle (closer in thermal expansion than aluminum, and 20ga is probably sufficient) could be added to the inner and outer edge to make a more durable joint, and one that can take knocking into tree branches and things. Another advantage of SS is that you can have any angle fabbed locally from sheet, so you have freedom in your design.

This is speculation... don't know of anyone who has done it that way.

 

[Alloy]

Finding a tried and true method to bond SS would be my worry.

FRF outside and alum inside would reduce the cost. To reduce expansion shorter sections of aluminums can be used.

4.000" x .250" Structural Fiberglass FR/UV GradeEqual Leg Angle at ePlastics

We sell Structural Fiberglass sheet and shapes

www.eplastics.com

The reinforcing along the outside corners doesn't need to be overkill. The internal structure (cabinets/walls) will add more strength than going overkill at the corners.

Bonding to a coating (paint/powered coating) introduces a layer that can fail.

 

[rruff]

Finding a tried and true method to bond SS would be my worry.

Why? It looks like nearly any structural adhesive works. It would be easier than bonding unanodized aluminum.

The beauty of SS is that you buy sheet and have it fabbed in the angles you want. With FRP and aluminum you are stuck with the extruded angles you can get... which appears to be 90 deg.

You could also make your own out of fiberglass/epoxy. It wouldn't be that hard at all. You could even join the pieces together to make an exoskeleton, then bond your panels inside. If you are good with CAD and can work out all the angles and dimensions, that would be a great way to go I think. If I had it to do over, I'd give that approach a try.

"Strength" is a very misunderstood term when it comes to camper boxes. Fiberglass has high strength (per weight) but low stiffness compared to metals. If you isolate the box from a flexible truck frame, then the loads on the box will be nil, unless you put a bunch of stuff on the roof... and in that case you are more interested in the roof being stiff rather than strong. Furniture can certainly add stiffness to the box, but this really isn't necessary... and if loads are induced from the truck frame, you'd rather have a flexible structure than a stiff one.

I think the more important quality is the ability to survive impacts, primarily from tree branches. That's where the edge reinforcement becomes important.

 

[Alloy]

Why? It looks like nearly any structural adhesive works. It would be easier than bonding unanodized aluminum.

The beauty of SS is that you buy sheet and have it fabbed in the angles you want. With FRP and aluminum you are stuck with the extruded angles you can get... which appears to be 90 deg.

You could also make your own out of fiberglass/epoxy. It wouldn't be that hard at all. You could even join the pieces together to make an exoskeleton, then bond your panels inside. If you are good with CAD and can work out all the angles and dimensions, that would be a great way to go I think. If I had it to do over, I'd give that approach a try.

"Strength" is a very misunderstood term when it comes to camper boxes. Fiberglass has high strength (per weight) but low stiffness compared to metals. If you isolate the box from a flexible truck frame, then the loads on the box will be nil, unless you put a bunch of stuff on the roof... and in that case you are more interested in the roof being stiff rather than strong. Furniture can certainly add stiffness to the box, but this really isn't necessary... and if loads are induced from the truck frame, you'd rather have a flexible structure than a stiff one.

I think the more important quality is the ability to survive impacts, primarily from tree branches. That's where the edge reinforcement becomes important.

For something like this I'd want a proven bonding system that is used in production.

No reason to be stuck with aluminum. Sheet/Plate/Extrusions are easier to fabricated vs. stainless.

I'd have an alum tub/pipe protecting the corners of the truck and camper box from trees

 

[rruff]

For something like this I'd want a proven bonding system that is used in production.

They use all sorts of adhesives on SS in production. And it's really more of a guard rather than something holding the panels together. The sketch Peter made is how his box is actually put together. It looks very iffy to me, but it apparently works! He put outer edge pieces on later for protection. Styromax builds them the same way... they have videos showing assembly. They even use pretty weak styrofoam cores.

Strong aluminum doesn't have the ductility to bend that far without making it weak... not in the thicknesses needed. Steel does. Custom extrusions are expensive. Aluminum and pultruded FRP are fine if 90 degree angles are ok with you, though.

 

[Victorian]

They use all sorts of adhesives on SS in production. And it's really more of a guard rather than something holding the panels together. The sketch Peter made is how his box is actually put together. It looks very iffy to me, but it apparently works! He put outer edge pieces on later for protection. Styromax builds them the same way... they have videos showing assembly. They even use pretty weak styrofoam cores.

Strong aluminum doesn't have the ductility to bend that far without making it weak... not in the thicknesses needed. Steel does. Custom extrusions are expensive. Aluminum and pultruded FRP are fine if 90 degree angles are ok with you, though.

dont forget to apply primer before bonding metal with adhesive…

correct, there are only 90 degree pultrusions to be found. We got 45 ones made to match our system. Again… expensive…

 

[Peter_n_Margaret]

My current vehicle is almost 17 years old now. I have NEVER had a glue failure (or any other panel failure except from a little poorly made panel that delaminated on the edges and was fixed during initial construction).
For the "important" joins I used Sikaflex 252 (plus the appropriate primer). The less critical ones are 11FC which is cheaper and easier to use.
I am now in the early stages of a new build. I will use a Wurth single pack polyurethane. It is much cheaper than Sikaflex.
I would like to have used pulltruded angles extensively, but weight & cost has brought me back to 1.6mm aluminium power coated extrusions plus a few custom folded pieces and a few spots using 3mm.
The strength of these glue joins comes from the large area of the adhesive.
Cheers,
Peter
OKA196 motorhome

 

[The Artisan]

14ga bent 4" angle, sika 252. Biltwell has has been using it for yr and a half with no worries, last trip was down to baja. The box was welded directly to the lmtv flatbed, not sure how the bed is factory mounted
Kevin

 

[Alloy]

Strong aluminum doesn't have the ductility to bend that far without making it weak... not in the thicknesses needed. Steel does. Custom extrusions are expensive. Aluminum and pultruded FRP are fine if 90 degree angles are ok with you, though.

Sorry but where are you getting this info about aluminum from?
- with FRP and aluminum you are stuck with the extruded angles you can get
- Strong aluminum doesn't have the ductility to bend
- Aluminum and pultruded FRP are fine if 90 degree angles

Please check your source because it's not true.

 

[Peter_n_Margaret]

I don't understand the reluctance to use custom folded aluminium sections.
3 years back I had a major prang. The front of the bed-over-cab aluminium sections were replaced. This is the bottom one of the two. Folded 3mm aluminium sheet. There is another at the top.
Not a big drama to make or fit. They are simply glued into place (the orange tape is holding it in position while the glue sets).
Use whatever materials are appropriate for each job or position.
Those bits are 3mm aluminium, as are the roof edges but they are extruded. Other bits where impact is a lower concern are 1.6mm extruded aluminium. The 45 degree leading edges of the bed-over-cab are 3mm steel because they take a hiding from the scrub.
Cheers,
Peter
OKA196 motorhome

 

[rruff]

Sorry but where are you getting this info about aluminum from?
- with FRP and aluminum you are stuck with the extruded angles you can get
- Aluminum and pultruded FRP are fine if 90 degree angles

Because you can get them in 90 deg angles but if you want something different, you have them custom made.

- Strong aluminum doesn't have the ductility to bend

Formable aluminum: Press brake bending 6061 with the 20% rule

Areas to consider for formable aluminum are formability, thickness and bend radius, tensile, yield, and elongation, and how to deal with bending tempered materials. Learn more here.

www.thefabricator.com

"6061 is the most versatile series within the heat-treatable family of alloys. In its annealed state, 6061 can be formed since the elongation is up to 18 percent and the difference between yield and tensile strengths is 10 KSI. However, as you move down the list of tempers, from annealed to T4 or T6, formability changes. This aluminum series’ ability to bend tends to decrease with temper. Bending these tempered alloys is not impossible, but it is very difficult and will most likely require larger bending radii to avoid cracking on the outside of the bend or completely fracturing at the bend line."

You can make a sharp bend in annealed and weak aluminum. For high strength aluminum you need a large radius which isn't ideal for panels that have sharp corners.

Stainless steel is much better in this application... custom angles for edge protection.