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Rocketpoxy
#11
(05-31-2013, 02:40 PM)gyoung link Wrote: If I go with the West system, I will have to mix 2 different fillers in correct?

No, you use the filler for the task.  US Composites has there own generic fillers, do not need to buy the marked up West fillers.

For the record I have NEVER seen or heard of any epoxy glue failure in the fin can area.  I am sure someday Goggins will have one, but  fin can joints are very very strong.  Lots of lineal area for the bonds, I am guessing plumbers putty will work.  Point being, don't obsess over the strength of the epoxy down there, that's not what is going to fail, ask Riedel or I will show you my Honest John fin can wreckage, everything destroyed except the fin root epoxy joints.

Adding Silica (Cab-o-sil) to the epoxy increases the adhesion and viscosity of the mix.  Chopped strands adds strength.  They're different.  For the fin can assembly you want adhesion, there is already plenty of strength.

Microballoons or Q-cells is added to the epoxy to weaken it so it sands better.  Use it for cosmetic purposes (nice fillets) where you want it to stay put.

On my builds I use Silica filled epoxy and make a very small fillet (radius ~1/8") for strength.  After that cures I go over that with a Q-Cell filled epoxy and make a cosmetic fillet (radius ~1/4") which I sand and make purdy.
John Derimiggio
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#12
Thanks  Mike and John!
John, that helped clarify the epoxy filler issue for me - silica for adhesion for the inner can, without the need for chopped fibers.
Same for the outside followed by a "cosmetic overcoat" with microballoon epoxy that can be better sanded. I got it!  Smile
Greg Young - L3
NAR #42065
TRA #00234
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#13
(05-31-2013, 07:12 PM)jderimig link Wrote: [quote author=gyoung link=topic=362.msg4184#msg4184 date=1370025627]
If I go with the West system, I will have to mix 2 different fillers in correct?


For the record I have NEVER seen or heard of any epoxy glue failure in the fin can area.  I am sure someday Goggins will have one, but  fin can joints are very very strong. 
Adding Silica (Cab-o-sil) to the epoxy increases the adhesion and viscosity of the mix.  Chopped strands adds strength.  They're different.  For the fin can assembly you want adhesion, there is already plenty of strength.
[/quote]

Heyyyyyy I beg your pardon.  If you were at the last launch ( wish I had it on video) you would have seen my new Big Bertha crash at terminal speed (stupid parachute).  Ha!  The fin can epoxy was intact.  The fins were destroyed as well as the body tube, nose cone, and av bay BUT, the epoxy held.  ;D 
I think I'm getting a reputation. 
Jg
Jim Goggins NAR  L3
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#14
For the record I have NEVER seen or heard of any epoxy glue failure in the fin can area.  I am sure someday Goggins will have one, but  fin can joints are very very strong. 
Adding Silica (Cab-o-sil) to the epoxy increases the adhesion and viscosity of the mix.  Chopped strands adds strength.  They're different.  For the fin can assembly you want adhesion, there is already plenty of strength.
[/quote]

Heyyyyyy I beg your pardon.  If you were at the last launch ( wish I had it on video) you would have seen my new Big Bertha crash at terminal speed (stupid parachute).  Ha!  The fin can epoxy was intact.  The fins were destroyed as well as the body tube, nose cone, and av bay BUT, the epoxy held.  ;D 
I think I'm getting a reputation. 
Jg
[/quote]

It sounds like you already might have one Jim!  Wink
Greg Young - L3
NAR #42065
TRA #00234
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