[roc-chat] Re: Mr Dierking suggestions/observations
- From: "Brad Ballreich" <bballreich@xxxxxxxxxxx>
- To: <roc-chat@xxxxxxxxxxxxx>
- Date: Mon, 20 Aug 2012 08:41:27 -0700
Whenever I've surface mounted aluminum fins to my airframes for my minimum
diameter projects, I've always sanded the epoxy into the root edge of the
fine to remove the surface oxidation. As I understand it, if you don't do
this, then your epoxy adheres to the surface oxidation which isn't really
attached to the aluminum structure underneath making the joint more prone to
failure.
Brad
From: roc-chat-bounce@xxxxxxxxxxxxx [mailto:roc-chat-bounce@xxxxxxxxxxxxx]
On Behalf Of Richard Dierking
Sent: Sunday, August 19, 2012 11:34 AM
To: roc-chat@xxxxxxxxxxxxx
Subject: [roc-chat] Re: Mr Dierking suggestions/observations
I've been using a scroll saw to cut the grooves. You could also use a band
saw, jig saw, or hacksaw. I had an extra fin for my recent project and
attached a photo. It's 3/16" Lexan, so sorry it looks a little weird in the
photo. However, you can see the cuts. After the cuts, I blow out all the
debris with an air compressor. Also I use the compressed air to clean the
MMT after roughing it up.
This greatly increases the amount of surface area for the bond.
Please let us know how the fin attachment works.
Richard
On Sun, Aug 19, 2012 at 11:14 AM, Mike Ostby <mdostby@xxxxxxxxxxxxxx> wrote:
I'm going to try Richards suggestion today regarding fin attachment. I'm
scratch building my first dual deploy and today is fin mounting day. It's a
4" BT with a 54mm MMT so there's not a lot of room to lay up fiberglass -
fin to MMT. (They will be glassed to the BT). So that I understand it
correctly, I need to "notch or groove" the root edge of the fins many times
aprox 1/8" deep? Thus sort of creating a serrated edge giving much more
surface area for bonding. Thinking of just using a bench grinder (the edge
of the grinding wheel) to make the notches. Is this the idea Richard? I've
not epoxied the aft centering ring yet so I'm able to still apply fillets.
Mike Ostby
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