Best way to joint fabricated carbon strut structure.

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Best way to joint fabricated carbon strut structure.

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Tobias	Tobias posted 12 Years Ago HOT Topic Details
Group: Forum Members Posts: 6, Visits: 16	Hi there, I am pretty new to working with carbon, but have a good background in other materials. I am working on designing a strutted framework, fabricated out of 5mm pultruded carbon tube, and I thought it best to seek some advice about how best to make the joints. My plan is to build a jig which holds everything flat, and use a braided sleeve to form a reinforced skin. However since I also plan on painting the structure, I don't necessarily need the braid for aesthetics, however I also don't want 'spider knees' at each join. To simplify things, lets assume i am building a small chair, with some structural triangulation, which needs to hold about 10kg ( so in real world terms I guess it has to be over-engineered to not fail under 50kg, or something of the kind ). In my crude drawing I have 3 potential jointing processes, but I wonder if there is another I have not considered, or if I would be better off making a mould and a core, and using a cast component joined by tubes, rather than attempting to join struts together. Thanks, T Attachments image.jpg (880 views, 114.00 KB) Tags Carbon joint pultruded tube strut
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Tobias	Tobias posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 16	It would appear that the ET515 has no structural value at all, as it seems to neither bond to degreased aluminium nor to roughed carbon, as in I can scrape it off either with my fingernail after three days of curing. I only discovered this when I had a catastrophic failure of a rather beefy join. I kind of feel that the ET515 is no stronger than Araldite, no more nor less rigid, and in a similar manner is no more respective of its apparent 15 minute working time. Warren (Staff) (11/07/2013) They should be bonded in using a structural adhesive like our ET515Semi Flexible 15min Epoxy Adhesive The braiding you want to add will just add further strength but isnt essential if you use inserts.
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carbonfibreworks	carbonfibreworks posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 292, Visits: 4.5K	Hello Tobias I have used the above adhesive on the top fairing mount on my classic racing motorcycle, i used it to join 10mm carbon tube to a piece of pre preg plate . I abraded the parts to be bonded with 180 grit paper and the part is under load and the joint has been 100% reliable. Regards Chris carbonfibreworks.co.uk
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Tobias	Tobias posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 16	Hmm, this was a 20mm carbon tube, and the join was to a strut coming in below, by means of an aluminium sleeve which wrapped around the tube like a clamp - made from 20x2mm stock.
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carbonfibreworks	carbonfibreworks posted 12 Years Ago HOT Post Details
Group: Forum Members Posts: 292, Visits: 4.5K	I will post an image of the part on Friday. Regards Chris carbonfibreworks.co.uk
	Reply Like 3

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Best way to joint fabricated carbon strut structure.

Tobias - 12 Years Ago

The strongest of the 3 is the tube joiner in aluminium. Such inserts are commonly used to join...

Warren (Staff) - 12 Years Ago

Hi Warren, So if you were to build such a structure, you would work with alloy inserts and a braided...

Tobias - 12 Years Ago

They should be bonded in using a structural adhesive like our Normal 0...

Warren (Staff) - 12 Years Ago

It would appear that the ET515 has no structural value at all, as it seems to neither bond to...

Tobias - 12 Years Ago

Hello Tobias I have used the above adhesive on the top fairing mount on my classic racing...

carbonfibreworks - 12 Years Ago

Hmm, this was a 20mm carbon tube, and the join was to a strut coming in below, by means of an...

Tobias - 12 Years Ago

I will post an image of the part on Friday. Regards Chris carbonfibreworks.co.uk

carbonfibreworks - 12 Years Ago

When bonding any metal I still use the wet sanding technique using 240 wet and dry sometimes 120 and...

Shaneer22 - 12 Years Ago

how big is the gap?? I have used ET515 personally for bonding inserts and its been a good bond. You...

Warren (Staff) - 12 Years Ago

As above, I've used that to bond halves of wings together and not had a failure yet

ajb100 - 12 Years Ago

I generally consider an adhesive to be something which adheres with a chemical bond, in this kind of...

Tobias - 12 Years Ago

If you are adhereing it to smooth (albeit degreased) aluminium then I would have expected the...

Warren (Staff) - 12 Years Ago

For future reference, I've just had confirmation from customer service at Permabond that the correct...

Tobias - 11 Years Ago

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Best way to joint fabricated carbon strut structure.

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