Carbon Fibre Foam Sandwich Sheets

[Geo.Lander]

Hi,

Well here goes probably a stupid question but in my defence it is motivated by a real obscenity, namely timber prices (up over 64% here in Norway from July last year, and just keep increasing).

I was planning on using 15mm birch 13-ply sheets for my furniture and cabinets(AA), but now cost an astonishing 800 euros per sheet (1550*2200*15). Even the poplar option and doing a DIY veneer job comes out at ridiculous prices to the point where carbon closed cell foam sandwich sheets are the same price or cheaper in certain configurations (without veneer)..

I'm getting to it, my question; has anyone gone down this road? Besides weight saving of course there are other benefits (fire, moisture, etc) but what exactly am I getting into here? My only experience with composites is the odd boat or kiteboard fibreglass ding repair..

 

[Madoxen]

Hey Geo, we have gone the route of composit foam/fiberglass for our cupboards and kitchen set up this worked out believe it or not cheaper than buying the timber to make it all. I guess we can get a vinal wrap made if need be making it look like what ever timber we want.

For the kitchen bench however we went with a nice chunk of hardwood for practicallity and looks which we will router out holes for sink and inductuon cook top.

To make out side corners look better than a composit join we are using L or triangular sections of wood or ally and bonding it to visible edges and corners. Feel free to ask questions as i may have already gone through the thought process and if not would be good to nut it out with some one

 

[Geo.Lander]

Hey Geo, we have gone the route of composit foam/fiberglass for our cupboards and kitchen set up this worked out believe it or not cheaper than buying the timber to make it all. I guess we can get a vinal wrap made if need be making it look like what ever timber we want.

For the kitchen bench however we went with a nice chunk of hardwood for practicallity and looks which we will router out holes for sink and inductuon cook top.

To make out side corners look better than a composit join we are using L or triangular sections of wood or ally and bonding it to visible edges and corners. Feel free to ask questions as i may have already gone through the thought process and if not would be good to nut it out with some one

Nice, thanks for this, I might look into GRP panels too then to keep costs more in check. I was wondering if you had any pictures from the bonding of your wood edging to the exposed foam core? i think the foam I was looking at was called Airex.. for joinery of the box sections what is the preferred approach? I have seen some studs like below but is bonding better? I wanted at least the seating to be fully removable so some type of bolts to my alu framing would be preferable..



I got this idea by watching (and dreaming) a video about carbon sandwich furniture on high performance boats, its all veneered carbon composites..

 

[Madoxen]

Will be happy to show pictures of all the bonding and edging once we have put it together its all flat packed in a container waiting on me getting the hab box assembled which i need to finish the subframe 1st ;-).

I will be using a combination of bonding and bolting . Bolts will be into frameing or bonded sections onthe walls.

 

[Iain_U1250]

Whilst not a carbon fibre composite, all our cupboards and internal lining of the box is made from a composite panel. I went with vacuum formed white laminex /1.8mm Ply / 5mm Aerogel foam /1.8mm ply /white laminex composite. It does take a lot of pre-planning for inserts and strong points as any foam composite is difficult to connect. I used aluminium angle inserts into the composite for the sections the need to be dismantled and anywhere you want to put screws I put solid wood inserts in. To finish off the edges, I routed out the foam, and glued in a strip of wood.


Making a box or cupboard involved gluing in aluminum into all the corners and where the shelves were going to be. You can see the cupboards in a trial fit below, once everything fitted, then the veneer was put on. The entire lining of the camper and all the cupboard weighed less than 100kg. I wanted 30mm thick bench tops, so use 10mm ply and 10mm foam for them. I did the design of all the cupboard and fixing, and had a boat builder make all the composite panels. It was painfully slow process, as due to the cost of the panel, and the need to get each aluminium insert in exactly the right spot, everything was trial fitted quite a few times before committing to the final vacuum press to put on the laminex outer skin or in our case, the Jarrah veneer.

 

[Victorian]

A couple years ago I came across a ultra lightweight veneer foam core panel made in house by a German expo truck builder. Very durable and light. The foam core was also dense enough to handle screws, just like plywood. Back in Canada we teamed up with several companies to create the same in high quantity. Unfortunately it turned out to be too expensive. A 4x8 sheet with a simple maple veneer would have been at least $1500! I don’t think anyone would be willing to pay this…..

 

[Geo.Lander]

Whilst not a carbon fibre composite, all our cupboards and internal lining of the box is made from a composite panel. I went with vacuum formed white laminex /1.8mm Ply / 5mm Aerogel foam /1.8mm ply /white laminex composite. It does take a lot of pre-planning for inserts and strong points as any foam composite is difficult to connect. I used aluminium angle inserts into the composite for the sections the need to be dismantled and anywhere you want to put screws I put solid wood inserts in. To finish off the edges, I routed out the foam, and glued in a strip of wood.
View attachment 681341

Making a box or cupboard involved gluing in aluminum into all the corners and where the shelves were going to be. You can see the cupboards in a trial fit below, once everything fitted, then the veneer was put on. The entire lining of the camper and all the cupboard weighed less than 100kg. I wanted 30mm thick bench tops, so use 10mm ply and 10mm foam for them. I did the design of all the cupboard and fixing, and had a boat builder make all the composite panels. It was painfully slow process, as due to the cost of the panel, and the need to get each aluminium insert in exactly the right spot, everything was trial fitted quite a few times before committing to the final vacuum press to put on the laminex outer skin or in our case, the Jarrah veneer.


View attachment 681344

Some great insights @Iain_U1250! It really is the fastening system and top storage lockers cutouts im worries about taking this approach.

 

[VerMonsterRV]

All of our major wall panels are honeycomb cored fiberglass skinned panels 30mm thick. I am very happy we went this route as the interior walls match exactly the side walls and ceiling. I think the honeycomb panels are also stronger than our sidewall foam cored panels. The glues holding the skins to the honeycomb seemed to be stronger than to the foam (the foam is the weak point). Plus the honeycomb crushes less if you thru bolt. The only drawback was I was limited to a single thickness of 30mm, which was a bit thick for some of the smaller panels. All edges were routed out and strips of maple bonded in with epoxy. For attaching the interior walls I made wood cleats that I pre-bonded to the exterior walls, then slipped on the routed out edge of the interior wall using Sika 252 to bond it onto the cleat. Pretty close to 2 years now and have not noticed a single failure of any of those bonds. I even made our bathroom door out of the honeycomb panel using the cutout from the wall.

We got our from Andreas (Total Composites), but not sure with the shipping if it would be worth it. We got ours at the same time as the rest of the habitat panels. There are other suppliers, I would check out boat building supply shops, I know I found one a couple of years ago but at this moment I can't remember the name.

 

[Iain_U1250]

One more thing, as Jon said, the foam is the weak part, the cupboards were glued to the wall panel with Sikaflex, and the edge of each panel was routed out about 5mm into the foam so we could get a enough surface area. The routed edge was filled with Sikaflex so we would get the minimum 3mm thickness whilst still having the edge of the panel flush with the back wall.

 

[tanuki.himself]

Personally i wouldn't swap internal plywood for anything as it is so strong to screw into and can so easily be patched and repaired if you change and evolve your internal layout over time and with use, but....

the provider of my fibreglass/foam panels used a specific foam called tancast in areas where i wanted mounting points and extra strength. Its still lightweight but does take a woodscrew/self tapping screw pretty well - certainly a lot stronger for fixing into than polystyrene or honeycomb

Tancast Range

Tancast is our range of high density polyurethane (PU) foam. Tancast can be easily machined enabling small prototypes to be made.

www.tridentfoams.co.uk

 

[Geo.Lander]

All of our major wall panels are honeycomb cored fiberglass skinned panels 30mm thick. I am very happy we went this route as the interior walls match exactly the side walls and ceiling. I think the honeycomb panels are also stronger than our sidewall foam cored panels. The glues holding the skins to the honeycomb seemed to be stronger than to the foam (the foam is the weak point). Plus the honeycomb crushes less if you thru bolt. The only drawback was I was limited to a single thickness of 30mm, which was a bit thick for some of the smaller panels. All edges were routed out and strips of maple bonded in with epoxy. For attaching the interior walls I made wood cleats that I pre-bonded to the exterior walls, then slipped on the routed out edge of the interior wall using Sika 252 to bond it onto the cleat. Pretty close to 2 years now and have not noticed a single failure of any of those bonds. I even made our bathroom door out of the honeycomb panel using the cutout from the wall.

We got our from Andreas (Total Composites), but not sure with the shipping if it would be worth it. We got ours at the same time as the rest of the habitat panels. There are other suppliers, I would check out boat building supply shops, I know I found one a couple of years ago but at this moment I can't remember the name.

Hi Jon, I have read your build pretty thoroughly, amazing quality workmanship Jon! We plan on using 30mm GRP panels for the bathroom, bed garage and maybe the closet too. This will be supplied and installed by the box builders.

I loved the maple details you had for for the edges and corners. If I go the full plywood route I will make the furniture all modular and removable as @tanuki.himself highlighted. However skills will probably limit me to pocket screw joinery with the 3M adhesive veneers but we are actually considering tooling up with a CNC router (partly for Thea's business) to help with some of the detail work, perhaps we could even use that for some nice dovetails but my CAM skills are still very much none existent..

Another route I am considering for the overhead cabinets and bedroom wardrobe (the one at the head of the bed) is full alu framing like our bedframe and seating area. The I could use some light 4-6mm ply with a nice veneer, not sure about fastening methods but it would be light (and really strong).

We have some time on our hands as the box build will only start once the windows have been delivered ⏳ We have added a lot of details to the design the last couple of months so are getting used to the fact this will be a looong build!

The blue highlighted panel are our 15mm plywood panels we had originally planned on using, they are supported by an aluminium frame, the same goes for the bed/garage (although that will be clad with 30mm GRP) and kitchen counter:-


Highlighted GRP panel sections to be build by the box manufacture:

 

[Geo.Lander]

Personally i wouldn't swap internal plywood for anything as it is so strong to screw into and can so easily be patched and repaired if you change and evolve your internal layout over time and with use, but....

the provider of my fibreglass/foam panels used a specific foam called tancast in areas where i wanted mounting points and extra strength. Its still lightweight but does take a woodscrew/self tapping screw pretty well - certainly a lot stronger for fixing into than polystyrene or honeycomb

Tancast Range

Tancast is our range of high density polyurethane (PU) foam. Tancast can be easily machined enabling small prototypes to be made.

www.tridentfoams.co.uk

Right, i was looking at Airex foam for the same properties, although no one seems to recommend tapping directly into the foam but using those expanding inserts (with poly sleeves) or just bolting right through it.. I agree about the module aspect of ply panels over bonded composites. We might still end up using plywood clad onto aluminium framing.. We might be able to make certain gains in lightness with the aluminium..

 

[VerMonsterRV]

We also used some plywood. I used a biscuit joiner for wood gluing cleats onto the edges of the plywood on the back side. Then bonded those cleats with the attached plywood bit to the walls. All of our cabinets are made this way. Makes for a very sturdy cabinet that also acts as a structural component as I tried as much as possible to have 90 degree panels in the panel edges to spread the load from the corner extrusions. So in between each cabinet door is a plywood panel with cleats bonded to the ceiling panel and the exterior wall. Using this bonding method I really didn't need to screw anything into the foam/honeycomb panels that would require backing, the 252 provides the strength. Time will tell but I know boats take a beating and 252 holds up very well in that environment.

Oh, a couple of things I missed in the build that I did end up thru bolting. The outside entry grabrail and awning. If I would have thought ahead I could have had the composite panels built with internal plywood pads that would have removed the need to thru bolt.