Which non expanding epoxy for bonding carbon fiber sleeves to barrel

[QVTom]

I think the strength of the adhesive is secondary to complete coverage.   No glue will come close to the stiffness of the CF, it real job is to fill the empty space.

Tom

[Bullit]

This is not a shroud but a barrel wrap. These aint cheap and would be an expensive lesson if the wrong products use.

I'll admit that I don't know what you're looking at Dave.  If it's a solid, carbon "arbor" sleeve, then a good epoxy blend will secure it.  If you're looking at physically wrapping carbon cloth, over the barrel, then you should get resin, and then the clearcoat for the final appearance coat.
Forgive that I'm probly slow on the uptake here

[lloyd-ss]

I have to admit that I have only bonded a CF sleeve to one barrel, but the results were good.  I have a fair amount of experience from previous years at my "paying job" dealing with epoxies in critical applications. 

Here is a look at some deflection testing I tried with a pseudo before and after with the CF sleeved barrel.  The CF sleeve does indeed greatly increase the stiffness of the barrel. 
I used Emerson and Cuming  24LV catalyst and 2651-40 resin to bond the sleeve.  This has excellent gap-filling properties, especially when the components to be bonded are heated slightly, which I did.  I suspended the barrel from a string to eliminate any side loading.  The barrel was .496 dia and the tube was .501 I.D.  The tube was heavily scuffed with 60 grit paper which raised enough of a burr to help center the barrel in the tube.  I brushed the epoxy onto the warm barrel and carefully "threaded" the barrel into the sleeve. The heavy burrs left from the 60 grit seemed to hold the epoxy to the barrel and help prevent it all from just being pushed off the barrel by the sleeve.

The EC epoxy is a high quality material I had on-hand that has characteristics suitable for the sleeving operation.
There are probably more readily available epoxies that are just as good, or better, but I haven't researched it.

Here are the results of the deflection test.
Basically the plain barrel deflected 64% more than the sleeved one.
Lloyd-ss

[grumpy]

Great post Lloyd. How did you keep the epoxy from getting in the barrel ?

[PakProtector]

for about 2' of joint overlap I can't escape the feeling that having both pieces wet will result in a better joint. it should be no issue to pour a bit into the liner and then push it onto the barrel( also painted ). This process *WILL* require some means of protecting the bore from glue. greased and or waxed patches crammed in the  muzzle end should do the trick. That and a bit of a mushroom over the crown to keep all the important bits clean( well, clean-able anyway ).
cheers,
Douglas

[QVTom]

Modeling clay is a good solution for plugging the bore.  Also, your local anodizing house will have silicone plugs for plugging holes that seal great. 

Tom

[grumpy]

Great idea, I have a shop right around the corner that sells it, and its cheap too

[lloyd-ss]

Great post Lloyd. How did you keep the epoxy from getting in the barrel ?

I only applied the epoxy tot he barrel, not to the inside of the sleeve, so that wasn't an issue.

[lloyd-ss]

for about 2' of joint overlap I can't escape the feeling that having both pieces wet will result in a better joint. it should be no issue to pour a bit into the liner and then push it onto the barrel( also painted ). This process *WILL* require some means of protecting the bore from glue. greased and or waxed patches crammed in the  muzzle end should do the trick. That and a bit of a mushroom over the crown to keep all the important bits clean( well, clean-able anyway ).
cheers,
Douglas

Doug, you are probably right that a light wetting of the I.D. of the sleeve wouldn't hurt.  A rubber cork from a hobby shop ought to keep the goo out of the bore.

During the prep of the barrel before the bonding,  I put a coarse 60 grit  cross hatch on the barrel which raised enough of a burr on the barrel to provide areas to trap the adhesive on the barrel as I slowly inserted and twisted the barrel into the sleeve.  I clamped a plastic stop on the barrel to positively locate the end of the sleeve  so that when the barrel was suspended vertically for curing, the adhesive did not have a way to run out the bottom.  Also, the warming of the barrel before applying the adhesive, and doing the initial curing at over 100 deg F greatly improves the flowability and gap filling of the epoxy. (With a slow cure epoxy.)  The epoxy I used is a potting compound designed for good flow, wicking, and gap filling. The job seemed to turn out ok.
Lloyd-ss 

[PakProtector]

for about 2' of joint overlap I can't escape the feeling that having both pieces wet will result in a better joint. it should be no issue to pour a bit into the liner and then push it onto the barrel( also painted ). This process *WILL* require some means of protecting the bore from glue. greased and or waxed patches crammed in the  muzzle end should do the trick. That and a bit of a mushroom over the crown to keep all the important bits clean( well, clean-able anyway ).
cheers,
Douglas

Doug, you are probably right that a light wetting of the I.D. of the sleeve wouldn't hurt.  A rubber cork from a hobby shop ought to keep the goo out of the bore.

During the prep of the barrel before the bonding,  I put a coarse 60 grit  cross hatch on the barrel which raised enough of a burr on the barrel to provide areas to trap the adhesive on the barrel as I slowly inserted and twisted the barrel into the sleeve.  I clamped a plastic stop on the barrel to positively locate the end of the sleeve  so that when the barrel was suspended vertically for curing, the adhesive did not have a way to run out the bottom.  Also, the warming of the barrel before applying the adhesive, and doing the initial curing at over 100 deg F greatly improves the flowability and gap filling of the epoxy. (With a slow cure epoxy.)  The epoxy I used is a potting compound designed for good flow, wicking, and gap filling. The job seemed to turn out ok.
Lloyd-ss

"An engineer by nature. The affliction is knowing that everything can be made better."
it seems you are already familiar with the issues involved...LOL
cheers,
Douglas

[lloyd-ss]

Douglas,
I was lucky enough to work with a lot of very smart people during my career, so if I didn't learn something new every day, it was my fault.  Its the same way here on the GTA.  A lot of smart people exchanging their ideas and experiences.  The next time I do one of these, I will try your suggestion and swap the I.D. with some of the epoxy before inserting the wetted barrel.  That is a good suggestion.
Thanks, Lloyd

[moorepower]

To plug the barrel all you need to do is squirt some rtv silicone in the end. A little solvent down the other end and it will come out when done.

[lloyd-ss]

To plug the barrel all you need to do is squirt some rtv silicone in the end. A little solvent down the other end and it will come out when done.

Good tip. Thanks!

[larspawn]

Is this just a carbon fiber wrap?  Or is this a vinyl wrap  I have used the self adhesive ones with good success.  I've also used the 3M spray adhesive with good results.  Spray, let get tacky and apply.  Great stuff.  If real epoxy I've used the two part epoxy from HD/Lowes.  I've used that to apply accent wood to stocks but have not used on CF.  Let us know what worked or not for you.

[lloyd-ss]

Is this just a carbon fiber wrap?  Or is this a vinyl wrap  I have used the self adhesive ones with good success.  I've also used the 3M spray adhesive with good results.  Spray, let get tacky and apply.  Great stuff.  If real epoxy I've used the two part epoxy from HD/Lowes.  I've used that to apply accent wood to stocks but have not used on CF.  Let us know what worked or not for you.

These are carbon fiber tubes, usually with about a 1/16" wall thickness that add substantial stiffness to the barrel and change the vibration characteristics..... and usually improve the accuracy too.
Lloyd

[rsterne]

Sean is now using CF tubes with a 1/8" wall bonded to the barrel.... 1/2" ID x 3/4" OD.... Stiffer than a steel barrel of 3/4" OD and a fraction of the weight....

Bob

[lloyd-ss]

Wow, 1/8" wall sounds really nice for performance! 
Added benefit: Fat barrels always look a whole lot cooler, too, IMHO.
Lloyd-ss

[larspawn]

Is this just a carbon fiber wrap?  Or is this a vinyl wrap  I have used the self adhesive ones with good success.  I've also used the 3M spray adhesive with good results.  Spray, let get tacky and apply.  Great stuff.  If real epoxy I've used the two part epoxy from HD/Lowes.  I've used that to apply accent wood to stocks but have not used on CF.  Let us know what worked or not for you.

These are carbon fiber tubes, usually with about a 1/16" wall thickness that add substantial stiffness to the barrel and change the vibration characteristics..... and usually improve the accuracy too.
Lloyd

Ahh I get what you are doing. Should have read all of your posts. So not so much the bonding but filling the space between them.  I see why you needed something viscous.