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6.10 Rocketry: Which is better, white or yellow glue? Epoxy? Cyano?




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This article is from the Model Rockets FAQ, by Wolfram von Kiparski with numerous contributions by others.

6.10 Rocketry: Which is better, white or yellow glue? Epoxy? Cyano?

From: bmcdermo@ix.netcom.com (Buzz McDermott)
Yellow wood glue, such as Elmers Carpenter's Glue or Titebond, is far
superior to regular Elmer's white glue for building wood and paper model
rockets. Built carefully, with proper fin fillets, yellow alphetic resin
will hold together on rockets with up to G power. Yellow glue also dries
faster.

Three and five minute epoxy is often used for quick repairs. This quick
drying time does not allow the epoxy to soak into the wood and/or paper
very well, though. If epoxy is to be used, then use one with at least
a 15 minute, and preferably a 30 minute, listed 'drying' time. Thirty
minute epoxy will give a much stronger bond than yellow glue. However,
5 minute epoxy often yields a weaker bond than yellow glue.

Cyano is often used for quick building. It bonds strong, dries extremely
fast (especially when using an accelerator), and is relatively easy to
use. Regular cyano can also be used to bond plastic to wood or paper.

No matter which glue is used, the most important factor is to have a
properly prepared surface. Glassine coated Estes-stype body tubes should
be lightly sanded where the glue is to be applied. All bonding surfaces
should be clean and unpainted. You want whatever bonding agent is used to
be able to soak into the paper and/or wood.

From: kingrat@sisko.dnaco.net (kingrat)
I've been using CA to bond fins to the tube and then a fillet of
epoxy. If you go this route I recommend thin CA and a fin alignment
guide. Make sure the fins are aligned properly before you CA and check
again before applying the epoxy. Unlike white glue, if you mess up it's
REALLY hard to fix. It's also REALLY hard to pop the fin off too. :)

This works just fine with balsa or plywood fins from what I've seen. CA
is good for tacking the lugs in place too, however I would never use CA
on a vital part of the rocket (ie. motor mount) CA just isn't strong
enough because it turns brittle. Epoxy will flex somewhat without
breaking and you can add microballoons to allow it to flex even more. In
short, use CA to tack and epoxy to bond.

From: rsantore@syr.edu (Bob Santore)
There is an easy test to tell if the glue you are using is strong enough.
A glue joint only needs to be as strong or stronger than the material it
is gluing together. To test for glue strength you need to test the
strength of the glue joint relative to the strength of the material you
are bonding. This test is very easy and can be used for any type of glue.
Glue some scrap pieces of whatever you are gluing together in a
configuration similar to how you intend to use it (i.e., don't test a
surface mounted fin if you intend to use a TTW fin). When cured, pull the
two parts apart. Did the glue bond fail? If it did, don't use that brand
of glue. If the pieces you glued didn't fail, then this glue is fine.
If your rocket falls apart anyway, then you need stronger rocket parts!
The only exception I can see to this very simple test would be near the
motor mount where heat can weaken the glue. You could always heat the
pieces before destructive testing to see if heat changes the properties of
the glue joint.

 

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