What adhesive system is best for bonding on carbon fiber hulls?

[Rezendes]

While I am not new to RC, I have never have built a boat from a bare hull until this year. I actually took on two builds. A 50? Raptor and a 52? TFL Ariane 3. Both hulls (one is my sons) are carbon fiber. I completed both builds in the last 4 weeks and we have been testing them for the last week. Most of the issues we have had are minor and just require an adjustment or two. However yesterday we were confident enough to start ?bumping up? the speed and along with that, the inadvertent ?flips?. Once I got home and started maintenance (remove prop shafts, etc) I noticed that some of the parts were starting to delaminate. On my TFL the large adjustable battery tray is starting to delaminate from the hull. On my sons Raptor, the same tray, one of the two motor mounts and stuffing tube support are also delaminating from the hull. I used EB 2 component epoxy, the type that comes in the syringe-like dispensers you buy at your local hardware stores. In Preparation for bonding, I rough sanded the part and the hull, wiped the surface to be bonded with 91% alcohol or acetone, mixed the two components added some black epoxy tint from Gougean and applied it to the parts. The epoxy had a 4-6 hour cure time and advertised to have 3900 psi bond strength.
So I am asking other builders, what did I do wrong, what does everyone else use to bond these parts on your boats?

Thank, in advance for your advice.

[Fluid]

You have discovered that cheap epoxy fails. Years ago I too discovered that generic epoxy often didn?t hold well at all. What to do?

I tested original JB Weld on several broken hulls - I could not remove the aluminum motor mounts I glued on without permanently damaging the hull (I did clean the hull and mount with alcohol first). Wait 24 hours before handling.

[Rezendes]

You have discovered that cheap epoxy fails. Years ago I too discovered that generic epoxy often didn?t hold well at all. What to do?

I tested original JB Weld on several broken hulls - I could not remove the aluminum motor mounts I glued on without permanently damaging the hull (I did clean the hull and mount with alcohol first). Wait 24 hours before handling.

I mis-spelled the adhesive I used it was JB epoxy that I used, not ?EB? two component epoxy. I am wondering if the black tint I used to the clear or grey JB may have caused the delamination?

[Fluid]

If the JB didn?t hold then IME you did something wrong. I do not know the effect of adding a coloring agent, all I know is that the original JB works great as is. I?ve not seen that product in syringes, can you post a pic of what you used? How long did you wait before moving the boat? Did you roughen the surfaces slightly before applying the epoxy? I normally do not but it might help.

How careful were you when applying equal amounts of each component? I assume very if you used the dual syringes....but again I?ve never seen original JB in dual syringes, did you use the clear version or something other than the original verision?

The chemistry of the different versions is different as are the holding strengths. For example the clear version is significantly weaker than the original formula.



.

[fweasel]

I've used the traditional JB Weld that comes in two separate toothpaste style tubes. I mix it by weight, and tint with dye with no negative results. Surface prep is key. I rough up surface when possible, and drill holes through plate like parts like motor and servo mounts to provide more surface area for the epoxy to grab on to.

[Rezendes]

How do I IME you?
Here are some photos of the products I used and the delaminated motor Mount and adjustable battery tray. As you can see from the motor Mount photo I drilled holes in the motor mount?s legs to increase adhesion and filed the tabs of the battery tray to match the angle of the hull to increase the surface area. I also roughed up the aluminum and carbon fiber surfaces prior to bonding. I also wiped the surfaces with solvent prior to adhesive application using alcohol or acetone. Typically, I would wait over night before moving the hull. All bonding was done one or two months prior to launching the boat.

[fweasel]

You're using JB Kwikweld. While I have no direct experience with that product, I do know that anything that cures fast is not as strong. This is the stuff that people use on mounts: https://www.amazon.com/J-B-Weld-8265...3549184&sr=8-3

[koen]

If you want a permanent solution use West epoxy system

[Rezendes]

I actually coated the inside of my hull with the West System Epoxy, but have not used it to bond any components, since, it, in itself is too viscous. If you have used it successfully for those types of applications what did you use as a filler to thicken it and still maintain a strong bond? What ratio of the blended resin and hardner to filler did you use?

[fweasel]

West System is a brand, not a specific mix of epoxy. I use their G-Flex epoxy to bond things to the inside of a hull. I use West System 406 Silica powder to thicken it for applications where I don't want it to run.

[meangenesracing]

West System is a brand, not a specific mix of epoxy. I use their G-Flex epoxy to bond things to the inside of a hull. I use West System 406 Silica powder to thicken it for applications where I don't want it to run.

Hello, I've never used the west systems g flex epoxy how thick is it compared to the regular west systems? Can it be used for carbon fiber inlays and thined down for sealing the outside skins of wood builds? Where do you get the silica powder? Thanks

[fweasel]

Hello, I've never used the west systems g flex epoxy how thick is it compared to the regular west systems? Can it be used for carbon fiber inlays and thined down for sealing the outside skins of wood builds? Where do you get the silica powder? Thanks

Couldn't tell you, West Systems makes a number of different resins that can be mixed with a hardener for inlay applications. I don't know what you've used in the past. No, G-Flex should not be used for hull inlays, it's too viscous. The 406 Silica powder is most often available from where ever you buy yoru other West System products. It comes in a white can.

[koen]

Yes you can seal a wooden hull and you can use it for carbon inlays
look at there site west system.com

[Old School]

I have used G-flex on several carbon fibre inlays and it works a treat. It is very runny though so care needs to be taken if a filler is not used. I initially purchased G-flex as I was doing an inlay on an ABS hull and all the literature pointed me towards the product. I continued to use it on later boats as I liked its performance. I also used it to bond fittings inside the hull although due its low viscosity one needed to carefully tilt the hull so that the resin stayed in the place you wanted it for say a fillet. I could have used a microballoon filler or similar to thicken it but did not have any onhand. I like the product but it is about twice the price of a similar volume West System epoxy resin.

[hughb]

There is a product that used to be available at Hobbyking called Easy Composites Vuduglu. It is a methyl methacrylate glue (whatever that means) and designed for composite-composite or composite-metal gluing. I used it on a boat for the motor and servo mounts and it worked great. Here’s a link to the product:

https://www.easycomposites.co.uk/vm1...ylate-adhesive