carbon fibre chainstays / seatstays - which epoxy ?

[NBC]

hi all

what epoxy do you use to bond carbon fibre chainstays and seatstays into steel frames ?

also what order do you put it all together ?

would like to get a better idea of what it all entails before ordering the parts

thanks in advance

NBC

[Mike Mcdermid]

hi all

what epoxy do you use to bond carbon fibre chainstays and seatstays into steel frames ?

also what order do you put it all together ?

would like to get a better idea of what it all entails before ordering the parts

thanks in advance

NBC

have you figured out your surface area? do you think its big enough, secondly have you calculated its big enough do you have the facility to cure the glue at temperature >70 degrees

the glues available to you in the 25-27Mpa range will give you a tensile value of roughly 3000psi however

more modern adhesives available can be nearly double that with a heat cure at 70-100 degrees

heres the instructions for an epoxy you could use http://www.3m.com/intl/kr/img/adh/ad...ries/DP460.pdf but may decide there are alternatives based on your own experiments or others advice ,page 3 gives interesting tips for surface preperation

^^^^^ disclaimer ^^^^^^

[NBC]

mike,

i was thinking about ordering a deda firebox / firetail rear end, along with the dedicated bottom bracket shell and connector tubes, i'd therefore presume they have a more than adequate surface area !

i've never used carbon frame components, hence the questions

what kind of setup would i need to heat cure ? are there not epoxies that will be strong enough with a room temperature cure ?

many thanks

NBC

[Mike Mcdermid]

mike,

i was thinking about ordering a deda firebox / firetail rear end, along with the dedicated bottom bracket shell and connector tubes, i'd therefore presume they have a more than adequate surface area !

i've never used carbon frame components, hence the questions

what kind of setup would i need to heat cure ? are there not epoxies that will be strong enough with a room temperature cure ?

many thanks

NBC

hey your probably good to go with the 3m or hysol or any of the structurals in the 30mpa range

heat cure just gets you a stronger adhesive cure some of the hexcel and permabond glues are double the strength of the 3m if you can heat em to cure them ,but its tried and tested on that setup

[Mark Kelly]

Re surface prep: for steels I adhere (!) strictly to the recommendations from Huntsman, the suppliers of the adhesive I use, and have found them to be uniformly excellent. For aluminium I use phosphoric acid anodisation since I don't have keroniting available to me.

A warning: the regime for stainless uses a pair of nasty noxious toxic and corrosive chemicals at elevated temperatures, best left to those familiar with the safety procedures required to work with such things.

[NBC]

what kind of quantity might i need per frame ?

the 3m comes in 50ml tubes, not sure how many to order

many thanks

NBC

[Mike Mcdermid]

Re surface prep: for steels I adhere (!) strictly to the recommendations from Huntsman, the suppliers of the adhesive I use, and have found them to be uniformly excellent.

you know the guys at Huntsman make their structurals in the UK ??,it gets shipped to belgium... if and only if you have stars and lay lines of the earth all in a row on a particular day and they are in perfect alignment you might be able to get some technical information out of the call centre which is routed to a frenchmans desk via switzerland and back to the UK to be told "non"

and your telling me you can get proper araldite in OZ?

we have replace hot melt prepreg with one of their xu resins though it blows everything else away their adhesives don't come close to hexcel or permabond heat cures though

[Mike Mcdermid]

what kind of quantity might i need per frame ?

the 3m comes in 50ml tubes, not sure how many to order

many thanks

NBC

Aye should be enough i glued an entire assembly bench together with a 50ml cartridge because i forgot to tap some holes in it
a 1/4 ton inspection table hasn't moved it yet

[Mark Kelly]

and your telling me you can get proper araldite in OZ?

I'm using their 420 A/B adhesive, seems to have pretty similar properties to the 3M DP420 and 460, apart from the colour (it's dark blue green). It looked to have the best properties of anything I could source locally without having to buy 5kg +. I'll look at the issue again when this lot is gone, but from what I have seen surface prep on stainless is the biggest influence on bond strength and I've got that nailed now (I had to buy the dichromate through the lab at the winery, they won't sell it to randoms, probably some stupid regulation).

The main drawback of the 420 A/B is the price: a 1kg + 400g package is over $300 here.

[Dave Anderson]

I've always used 3M DP460..... As far as order goes...I am not exactly sure what you mean there...but you build the steel triangle first and then glue on the rear. The upper connector can be a little tricky to align and miter and so I have always mocked that up with a dry fit of the rear end, etc. Beyond that, I cut the chain/seat stays to length on the drop out ends and align and glue those up (and let them cure) before mocking up or attaching the rear to the front triangle. Its also a good idea to dry fit the chain stay assembly to the BB shell and get that aligned before tacking the BB shell to the tubes, so that the chain stay socket is lined up properly with the chain stays, etc.

Dave

[Mike Mcdermid]

I'm using their 420 A/B adhesive, seems to have pretty similar properties to the 3M DP420 and 460, apart from the colour (it's dark blue green). It looked to have the best properties of anything I could source locally without having to buy 5kg +. I'll look at the issue again when this lot is gone, but from what I have seen surface prep on stainless is the biggest influence on bond strength and I've got that nailed now (I had to buy the dichromate through the lab at the winery, they won't sell it to randoms, probably some stupid regulation).

The main drawback of the 420 A/B is the price: a 1kg + 400g package is over $300 here.

Im just more intriqued its available ,phosphoric ano we used to loosely interpret or call boeing process

[Dave Anderson]

Aye should be enough i glued an entire assembly bench together with a 50ml cartridge because i forgot to tap some holes in it
a 1/4 ton inspection table hasn't moved it yet

Yep...I don't think I've ever used more than one for just a rear end. However, it wouldn't hurt to have two just in case. It's not hard to waste a bunch on the first go round.

[NBC]

thanks guys, i really do appreciate it

by order of assembly, i mean do certain parts need to be bonded together even for mocking up purposes ?
i.e do the dropouts need to be bonded to the chainstays, even if the plug for the bb shell is't already cut down to length etc etc

then when bonding up finally, do you put the seatstay part in first, or the chainstay part ?

any advice would be great :)

thanks

nbc

[Dave Anderson]

I am sure that there's more than one way to do it, but what I have done is mock up the chainstays, drops, shell and seat tube before gluing or tacking anything:



Then I build the front triangle. I then bond the seat stays and chain stays to the drop outs and dry fit the rear end into the front end as I work out the upper end of the seat stay and connector configuration:



One thing to be mindful of is that the drop out ends of the stays are often supplied a little long and so you'll want to work out your brake reach and wheel clearance before trimming those to length, etc.

When bonding the rear end into the frame, I do it all at the same time, but install the chainstays first and then the seat stays...or vice versa...doesn't really matter. (On all of the rears that I've used to date, the seat stays were hinged at the drop outs with removable bolts, which allowed them to be separated and, therefore, easy to manage when gluing them up, etc.)

Dave