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  #1  
Old 12-13-2008, 11:46 PM
Bluegrass Rocket Bluegrass Rocket is offline
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Default Your glue fillet secrets

Help! I have been having trouble getting smooth glue fillets on my fins. It doesn't seem to matter what glue I use, I still get a bunch of air bubbles. I don't remember having this big a problem in years past. So, I was hoping some of the great builders out there would share their secrets on good smooth glue fillets. Thanks for any help.
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  #2  
Old 12-14-2008, 12:01 AM
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dwmzmm dwmzmm is offline
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Air bubbles?! When I get air bubbles in some of my builds (and I DO get them from time to
time, so you're not alone), it's usually due to a slightly clogged nozzle of my white glue and
also when the glue bottle is almost empty. Excessive air pockets is being expended as the
glue is applied to the fin/body tube joint. If I see any air bubbles during my builds, I immediately "pop" them and apply a dab of white glue to the spot(s) and smooth the fillet
with my finger again (or repeat the step as necessary until the job is done right).

Hope that helps. I'm sure others will chime in on their theories and solutions (I'm still all
ears!).....
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Old 12-14-2008, 01:37 AM
GIJoe GIJoe is offline
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I have noticed that when I use Yellow Glue for fillets it always dries with small holes in it and requires at least a second coat. It makes no difference if I make big or small fillets, there are always holes when the glue dries.
My favorite for fillets is 5 minute epoxy, although some guys will tell you that is over building. I just like the way it flows and sets up. It is also easier for me to hide a small gap in a long fin.
I always tape off my fillets first, leaves a cleaner line. I also use my finger to smooth them out.

Joe
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Old 12-14-2008, 06:58 AM
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Bob Kaplow Bob Kaplow is offline
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Default Oh, no, a GLUE thread!

Quote:
Originally Posted by GIJoe
My favorite for fillets is 5 minute epoxy, although some guys will tell you that is over building. I just like the way it flows and sets up. It is also easier for me to hide a small gap in a long fin.


IMHO 5 minute epoxy has no place in our hobby. I can't imagine anything worse for fillets. It has NO heat resistance, and it is so thick that it can't flow out into a good fillet.

If you're building with yellow glue, there is nothing wrong with using yellow glue for fillets. My THOY Hornet (Graduator / Initiator sized rocket) is built with nothing but yellow glue for everything, and has flown repeatedly on H motors.

When I do use epoxy for fillets, or anything else for that matter, its one of the laminating resins (System 3, West, Raka) with a very slow hardener and when appropriate some micro balloons or other additive mixed in.

When I need something that sets faster than medium cure (hour +) epoxy or yellow glue, I use CA, or in certain cases hot melt glue.
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Old 12-14-2008, 08:19 AM
Indiana Indiana is offline
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Default

I use this stuff. Its viscosity is about half way between white glue and paste. It makes very nice fillets in one application. It does not shrink when drying nearly as much white or yellow glue.

Available at your local home improvement store.



I can't figure out how attach images (as opposed to linking to hosted images) so that's the only picture I can offer.
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  #6  
Old 12-14-2008, 10:22 AM
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Gus Gus is offline
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Rick,

Where weight is not a critical issue, I really like
Apogee's Fix-It Epoxy Clay for fillets.

Very easy to use, plenty of working time, makes great looking fillets.

You roll a little bit of the clay into a thin worm the length of the fin, place it where you want the fillet, then run a wet popsicle stick over it to form it to shape. Takes a little practice but makes great looking, very strong, fillets.

For competition models I use thin CA and accelarator.
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Old 12-14-2008, 12:51 PM
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tbzep tbzep is offline
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Quote:
Originally Posted by Bluegrass Rocket
Help! I have been having trouble getting smooth glue fillets on my fins. It doesn't seem to matter what glue I use, I still get a bunch of air bubbles. I don't remember having this big a problem in years past. So, I was hoping some of the great builders out there would share their secrets on good smooth glue fillets. Thanks for any help.


To minimize bubbles, I make a solid bead of glue down the length of the joint, but make the bead small so that I'm not wasting a bunch. I get very few bubbles, but when I do, I just take my x-acto knife aand pop them. The glue will flow back into the holes and level out. This is with both yellow and white glue.

If I for some reason still end up with a bubble, I simply fill it with fill-n-finish when I'm filling the balsa grain.
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Old 12-14-2008, 09:14 PM
duobob duobob is offline
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I'm with tbzep I have found that storing my glue bottles nozle down helps as well.
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  #9  
Old 12-14-2008, 09:51 PM
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dwmzmm dwmzmm is offline
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Quote:
Originally Posted by duobob
I'm with tbzep I have found that storing my glue bottles nozle down helps as well.


Great idea! I should have known about that, as I've seen the sandwich makers at Sub Way
do that to the mayonnaise/mustard squeeze bottles too.
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  #10  
Old 12-15-2008, 06:21 AM
Peartree Peartree is offline
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Yellow glue often dries kinda "funny" and seems more prone to leaving gaps or holes. I have sometimes used yellow glue as my first pass fillet, sanded a little and then used white glue on the second pass as more of a gap filler than for any need to add additional strength.
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