For purely cosmetic filling, I like to use SuperFil. It's two-part
and it cures like epoxy but is very light and doesn't sag so works
perfectly for filling.
http://www.aircraftspruce.com/catalog/cmpages/superfil.php
John
On Tue, Jun 7, 2016 at 9:11 PM, Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx> wrote:
Thanks everyone! The fins are TTW and I used RocketPoxy for the main
construction. It's already flown once successfully without fin fillets so
this would be more aesthetics and aerodynamics than structural, although we
plan to use bigger motors.
I love the rotisserie idea, too! :)
Amazon orders can be weird sometimes. The Rectorseal showed free same day
with Prime but when I added it to the cart the earliest was Thursday (other
items in the same cart are coming today). So, I guess I’ll have to drive to
a hardware store… the horror… ;)
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx]
On Behalf Of Alexander Jones
Sent: Tuesday, June 7, 2016 11:56 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Epoxy putty
Yeah, there is a bit of a whet out problem with it, but if you dip your
finger in a bit of isopropyl alcohol and run your finger along it, it helps
lubricate and slightly softens the putty without affecting the cure, so you
can get okay-looking fillets just doing that. You can then sand it down
fairly easily. I've also used EWF to add easily sandable material on top of
this stuff, allowing you to shape it down to a nice aesthetic fillet without
expending a ton of effort to sand the epoxy clay. I like to try new
techniques with each rocket's fillets, though, and I think my next one will
be using the John Coker method, using a pretty heavily thickened/filled long
cure, like West System, then use a plastic spoon to remove the excess and
shape it. I would like to try your method, though, too, just letting
gravity do its thing. My only concern is getting it evenly distributed
between fin and airframe, especially on 3-fin models -- I like the
rotisserie idea.
On Tue, Jun 7, 2016 at 11:46 AM, Kenneth Brown <ken@xxxxxxxxxxxxx> wrote:
The problem with putty is that it doesn't whet out to the body and fin since
it's so viscous. I prefer to use a 60min epoxy (longer set times generally
mean a stronger bonding epoxy) filled with microspheres to thicken it
slightly and then put the body on a rotisserie horizontally to keep the
epoxy from sagging. I get very nice fin root fillets this way. I should add
that I will pin the fins in place with a couple of spots of super glue to
hold the fins in place while the epoxy cures.
Ken
On Jun 7, 2016, at 11:38 AM, Alexander Jones wrote:
Adrian, it looks like you can get this stuff at some home depot stores,
apparently in the plumbing section. On another note, I've had okay results
with the loc-tite brand stuff that's also available off the shelf at HD (I
tend to go for the stuff that's wet applicable, which might explain my
success with it re: the brittle issue), but it really depends how much
stress you're planning to put on the joint. If it's minimum diameter or
you're otherwise expecting super-high accelerations and mach+ speeds, I'd
reevaluate it....if you're staying below mach and you're using a robust fin
attachment like TTW, you should be fine. Also, all the putties are actually
A+B, just some of them combine it into one "log" of putty, with the hardener
in the outside layer, usually the colored layer, then the epoxy is the core
and is usually white or at least lighter-colored....you use a plastic knife
or something to chop off a little section of the log and just knead it
together until it's homogeneous.
On Tue, Jun 7, 2016 at 11:02 AM, Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx>
wrote:
Thanks Alexander and Mike!
I can’t get the Amazon order to work (and have been using Prime for years)
so they may not have it in stock for same day. They do have A+B epoxy putty.
It’s for fin fillets and what I’ve read is that some putty is too brittle
and the fillets break off.
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx]
On Behalf Of Alexander Jones
Sent: Tuesday, June 7, 2016 9:44 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Epoxy putty
Adrian, looks like you're in luck, there's a rocketry forum post where a
guy gives a brief review of this exact product:
http://www.rocketryforum.com/showthread.php?74822-Rectorseal-EP-400-Epoxy-Putty-Works-Great!
On Tue, Jun 7, 2016 at 9:41 AM, Adrian P. Bailey <adrian@xxxxxxxxxxxxxxx>
wrote:
Has anyone used Rectorseal Ep-400 Epoxy Putty, or have other
recommendations? I’m looking for something that Amazon can deliver today… ;)
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