Double layer tube

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Double layer tube

Double layer tube

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GreyArea	G GreyArea posted 8 Years Ago HOT Topic Details
G Group: Forum Members Posts: 36, Visits: 65	Does anyone know a company that could make me small quantities of a double walled tube? The first (inner) tube to be 1.5-2mm wall, clear resin with a single layer of 80gsm woven glass fibre (preferably as close to the inside of tube as possible), the outer tube to be “normal” carbon fibre with standard 1.5mm wall and the outer diameter to be 25mm. Odd request I know...but then I did say I was the mad scientist...
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GreyArea	G GreyArea posted 8 Years Ago HOT Post Details
G Group: Forum Members Posts: 36, Visits: 65	Thanks oekmont, you certainly know your stuff. For now I’ll continue with my frosted acrylic inner tube/carbon fibre outer tube and a bonding layer between them that contains some (as yet unspecified) layers of 80 gsm weave. Can someone at easy composites let me know the best clear epoxy/pu from their range to do this operation please? Thanks - by the way I’m assuming it will be January for delivery now?
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Double layer tube

GreyArea - 8 Years Ago

The Problem will be to her a 1,5mm thickness with only a single layer of 80g glass in it

oekmont - 8 Years Ago

That’s interesting actually...how many layers of weave are in a normal 1.5 mm wall tube?

GreyArea - 8 Years Ago

The problem is, that composite tubes (not the pultruded ones, they are are made completely different) of that diameter are usually rolled prepreg over a steel mandrel. The consolidation is achieved b...

oekmont - 8 Years Ago

More mundane than that...I’m looking for something translucent within something opaque (and aesthetically pleasing) with high rigidity/strength. It’s possible that more gf weaves would still be light...

GreyArea - 8 Years Ago

What about an acrylic tube? You would need 19x22, I found 18x22 within a quick search of 10 sec. Key it, and wrap carbon around it. Prepreg might exceed the thermal specs of acrylic, but it should be...

oekmont - 8 Years Ago

I already tried a frosted (works well as a key) acrylic tube, but I’d prefer at least some sort of fibre reinforcement in it for rigidity...and then I need that to have sufficient covering of resin.....

GreyArea - 8 Years Ago

What loads have the tube to take? If i should be structural in any way, a 80g glass reinforcement is as good as no reinforcement at all. No clear material comes near the propertys of carbon reinforce...

oekmont - 8 Years Ago

What about an inner tube of thin fibreglass, then cast the clear resin section of the tube around the fibreglass tube, then bond that into the carbon tube? Not an easy process at all for sure. That....

Hanaldo - 8 Years Ago

If the tube inner and outer are carbon fibre then this will mostly take all or any loads, the inner clear part may not need any fibre reinforcing at all? Why not set up two carbon tubes with the...

Fasta - 8 Years Ago

I think he wants the inner tube to be translucent, so not carbon. And he wants to cut sections out of the outer carbon tube so that light shines through, but that will affect the carbon tubes ability...

Hanaldo - 8 Years Ago

I’m already doing the “cast a tube between two tubes” process and you’re right it’s a pain. Apart from ensuring the tubes stay coaxially centred there is as you say not much clearance.Loads are...

GreyArea - 8 Years Ago

I think either a thin walled grp tube/layer or a pre-made clear plastic tube bonded in is the best simple solution. How much load are you trying to take?

Warren (Staff) - 8 Years Ago

There is another problem with your idea. Glass and carbon got greatly different young's modulus. Wich means that your resin layer will take huge loads under stress, because the outer layer will defor...

oekmont - 8 Years Ago

All excellent points. It all comes down to the actual load this thing needs to handle. What about a polycarbonate inner tube then? Significantly stronger than acrylic, and would be incomparably...

Hanaldo - 8 Years Ago

Loads are hard to estimate, but maximum I guess could be 60kg or so...but as I said it could act in a number of directions.Nominally, think of the tube as a prop, so in perfect use it’s loaded down.....

GreyArea - 8 Years Ago

600N is quite a load for a 25mm rod including bending and torsion. If the light should be opaque anyway, a solid grp tube might be enough. After you cut out the design, give it a laquer finish, and.....

oekmont - 8 Years Ago

I have considered that...but I’ve been distracted by the pretty woven finish on Carbon fibre rods. Might have to source some GRP tube...suppose can always paint it black lol.

GreyArea - 8 Years Ago

I think oekmont meant a solid grp tube inside the carbon tube... That way the fibreglass tube is the structure, and the carbon is just on the outside for aesthetics and the design. Alterntively, you...

Hanaldo - 8 Years Ago

I got confused by “solid tube” cos to me that sounds like a rod...I still need a void down the middle...or does solid mean opaque?I’ve just received my square metre of 80gsm weave and more good...

GreyArea - 8 Years Ago

8 layers of 80g glass fibre results in about 0,4mm thickness. This will not hold 600N of dynamic force on the end of the tube.

oekmont - 8 Years Ago

Polyester is the worst choice in this application, as polyester has really bad bonding characteristics to epoxy. Epoxy or polyurethane will give much better bonds.

oekmont - 8 Years Ago

Thanks oekmont, you certainly know your stuff.For now I’ll continue with my frosted acrylic inner tube/carbon fibre outer tube and a bonding layer between them that contains some (as yet unspecified)...

GreyArea - 8 Years Ago

Oekmont...and anyone else, you’ve all been very helpful...does using the internal acrylic tube affect whether you’d recommend pu or epoxy for the bonding? Adhesion to the inner acrylic tube is...

GreyArea - 8 Years Ago

Acrylic is fairly easy to bond to as far as plastics go, but considering the loads you are speaking of you may actually struggle a bit here too. Epoxy will bond to it reasonably well, but you will...

Hanaldo - 8 Years Ago

I would still recommend using a grp tube and get a layer of braided carbon on it. This will be a few times quicker, much stronger, cheaper, better to replicate the results, and likely just as...

oekmont - 8 Years Ago

I understand what you’re saying about the thickness of the CF layer, but counterintuitively it needs that thickness so that the effect of the translucent black pigment is maximised when the design is...

GreyArea - 8 Years Ago

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