fin removal

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dogfight

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Haven't run into this issue before and figure you guys have so looking for advice - fins are glued on and solid but at an angle so need to come off for remounting. Whats the best way to remove them for reattachment without damaging the bt?
 
That depends on what they are glued on with.

White glue can be loosened with heat - you can actually straighten a bent fin by warming the glue joint over a 100 watt light bulb or, as I have done, with a monocote sealing iron. If you warm it enough, you may actually be able to reposition the fin (if you don't have to actually move it) or pull it off if you do. I think yellow glue is also heat sensitive, but I don't know for sure.

If you used CA or epoxy, I'm not sure there is anything that will dissolve that joint that won't also destroy the fin and/or the body tube. Your best bet might be to cut the fin can off just in front of the fins and build a new fin can. Then use a body tube coupler to connect the new fin can to the rest of the rocket. Of course, by that point, you are almost at building the rocket over again. Also, putting a coupler just in front of the fin can will move the CG backward some, so repairing a marginally stable rocket like this may make it unstable. Check your CP/CG again before flying.
 
most of the hobby shop epoxies will soften as the get warm...but you're talking about temps around 200F.
 
Actually epoxy will also become pliable with heat and may make it easier to remove. I typically will use a heat gun, or a hair dryer might work.
 
Some glues - many white and wood glues - also get softer from water exposure. Use a hot glue gun to make a little wall around the glue joint, pour a little water on, let it sit.
 
did you put much in the way of fillets on the the fin Bt join?

if there is little i the way of glue present, then you can (carefully) run a very sharp blade down the fin join from the top. - i've only done this once.

if i have to take a fin off a rocket now, i usually destroy the fin, balsa is not the expensive part of the rocket. I use a band sander in the workshop and sand the whole lot off, fin, fillet, paint etc, and then attached a cloned fin.
 
Thanks for the replies I'll do some surgery tommorrow starting with low heat and go from there. Was kind of hoping for that " oh ya use that there instant glue removal stuff" but sounds like there's no such thing
 
If you used carpenter's (yellow) glue, vinegar will soften it enough that gently rocking the fin back and forth will separate it from the body tube. You may need the assistance of an exacto knife if the fin is stubborn being.

Bones
 
well i know there is something to dissolve CA, but i can't remember exactly what. at my local hobby store i saw "super glue dissolvant" which im guessing is just acetone or something.
 
dogfight,

I have a fin jig to show you, it is real good at all those fin aggravations. Almost makes it to easy. Sent you a pm too, re. club meeting.

Scott
NAR91379 L0
 
Acetone will dissolve the CA. But make sure you have good ventilation.
 
You mean you guys never heard of CA debonder? :rolleyes:

You can find it in any Hobby lobby next to the Ca glues....
Pro Ca, great Plains, ZAP, Super Jet, Extreme Power, they all make it.......
 
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Thanks for the tips
I used the hair drier and an exacto knife plus a little gentle pressure worked great. It's time to make a fin jig to put them back on straight.
Scott read about them in a rocket design book.
Good news on the field :point:
 
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