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How do you attach a cowl to cowl ring?

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Old 04-10-2014, 01:08 PM
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catboater
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Default How do you attach a cowl to cowl ring?

Wondering what adhesive you guys use to attach a fiberglass cowl to a plywood cowl ring.
The 30 minute epoxy I used let go on the first flight.
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Old 04-10-2014, 01:33 PM
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I think that surface prep is just as important as what adhesive to use. Your 30 minute epoxy should have been fine. Did you sand and clean the bonding area of the fiberglass first?
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Old 04-10-2014, 01:42 PM
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I always like to wipe down the area with some rubbing alcohol, then I will rough it up good with some coarse paper, and wipe it down again , after it dries...Then I will glue it . I can't prove its the best technique but I always have the rubbing alcohol on the bench and it seems to work well.

Last edited by foodstick; 04-11-2014 at 05:01 PM.
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Old 04-10-2014, 02:20 PM
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Exactly

I would also add some micro balloons or milled fiberglass to 30 minute epoxy.

The best stuff you can use though is a product called Epo Grip
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Old 04-10-2014, 03:02 PM
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I'll second the micro balloons/milled fiberglass approach. Also, I don''t just edge glue the ring but form a small fillet on both sides of the ring as well.
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Old 04-10-2014, 03:09 PM
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Edwin
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I use goop from the hardware store. Never had a problem.
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Old 04-10-2014, 04:00 PM
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When the cowl is polyester resin I use polyester resin with microballoons. If the cowl is epoxy I use epoxy resin and microballoons. Rough the surface od the cowl and clean well where the adhesive has to go.
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Old 04-10-2014, 06:26 PM
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jester_s1
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Making a fillet is really important. It triples your gluing area and braces the joint from flexing.
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Old 04-10-2014, 06:40 PM
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I glue all my 3/32 thick basswood plywood rings into my epoxy cowlings with thin CA, I then place 2 plies of 6 oz. glass cloth 1.5" wide on the inside using epoxy resin along with a fillet of wet micro or cab, and of course prepping the bonding surface with at least 180 grit sand paper is a must.

Bob

Last edited by sensei; 04-11-2014 at 02:34 AM.
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Old 04-11-2014, 04:55 AM
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Scuff the fiberglass. Wipe it with alcohol to clean it. Tack glue the ring in place with CA and then make a fillet of Shoe Goo. It holds great.
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Old 04-11-2014, 05:57 AM
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+1 on the EPO Grip, ASSUMING this is an epoxy/glass cowl and not polyester resin/glass.
great stuff!
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Old 04-11-2014, 08:54 AM
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So how do you tell the difference between an epoxy/poly cowl and fiberglass?
Is there no cloth in epoxy/poly?
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Old 04-11-2014, 09:55 AM
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Epoxy or Polyester is just the resin system that the cloth was infused with. When you sand on it, polyester will have a strong smell, epoxy will not. There is a debate ( isn't there always ) whether you have to use the same resin system that the part was made from. IMO you can use epoxy to bond wood onto polyester parts just fine. Just remember that the bond is only as good as your prep. The surface must be scuffed and clean. Don't skimp on the clean, your part at this point may be oil contaminated. Wash with Dawn dish soap, scuff and wash again with Dawn. Adding fillers to the epoxy won't hurt but also don't add as much strength as some would like to believe. As Sensi has stated, the best way to make it bullet proof would be to add some cloth to the joint.
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Old 04-11-2014, 03:12 PM
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speedracerntrixie is correct. You can use epoxy to bond things to parts made from polyester resin. However, polyester resin does not bond well to parts made from epoxy. So, regardless of what your cowl was made with, you should be OK using epoxy. BTW, epoxy is much safer to work with. Polyester resin has a very strong odor, it generally has less working time than epoxy, and the hardener can cause blindness if you get any in your eyes.
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Old 04-15-2014, 08:39 AM
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Just another option/thought here. I have glued many items of dis-similar materials together with Zap brand Ric560 Canopy Glue and later was unable to separate the items without destroying them. I have not tried it on a cowl ring, but it might work. Tower sells it.
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Old 04-15-2014, 06:12 PM
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+1 prep prep prep
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Old 04-16-2014, 09:18 AM
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Yes, yes, yes
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Old 04-16-2014, 10:51 AM
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Hysol 9462 or E20HP depending on how much of a hurry i am in.
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Old 04-16-2014, 04:06 PM
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The reason I add fillers is to keep the 'glue of choice' in place. It's kinda runny otherwise! Once the well fitted ring is in place and 'glued' properly the chances of the parts parting is slim.
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Old 04-16-2014, 04:39 PM
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Originally Posted by ARUP View Post
The reason I add fillers is to keep the 'glue of choice' in place. It's kinda runny otherwise! Once the well fitted ring is in place and 'glued' properly the chances of the parts parting is slim.
Hysol 9462 is thixotropic (doesnt sag on a vertical surface) and E20HP is slightly thixotropic so it will permiate into wood slightly and E00NS is runny and permiates into wood very well. All are aerospace quality adhesives and offer very strong bonds.

9462 bonding two pieces of 1/8" aircraft ply will actually tear a layer or two of the ply away from the part without any damage to the glue joint/fillet.
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Old 04-17-2014, 08:26 AM
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Ware do you get your hysol in small qty's
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Old 04-17-2014, 11:07 AM
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Originally Posted by rt3232 View Post
Ware do you get your hysol in small qty's
Dreamworksrc.com
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Old 04-17-2014, 04:17 PM
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Originally Posted by invertmast View Post
Hysol 9462 is thixotropic (doesnt sag on a vertical surface) and E20HP is slightly thixotropic so it will permiate into wood slightly and E00NS is runny and permiates into wood very well. All are aerospace quality adhesives and offer very strong bonds.

9462 bonding two pieces of 1/8" aircraft ply will actually tear a layer or two of the ply away from the part without any damage to the glue joint/fillet.
The reason I add fillers to my 'glue of choice' is so that I don't have to have a separate glue for every separate 'persnickety' job building models. Water based wood glue, nitrocellulose based, slow and fast two part epoxy and polyester resins are all I need. Your mileage may vary. Also, my 'glue of choice' is sufficiently strong so aerospace quality is an overkill, IMHO. I'll be waiting for the come-back!
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Old 04-17-2014, 04:56 PM
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Originally Posted by ARUP View Post
The reason I add fillers to my 'glue of choice' is so that I don't have to have a separate glue for every separate 'persnickety' job building models. Water based wood glue, nitrocellulose based, slow and fast two part epoxy and polyester resins are all I need. Your mileage may vary. Also, my 'glue of choice' is sufficiently strong so aerospace quality is an overkill, IMHO. I'll be waiting for the come-back!
Yea i agree its not necessary for 90% of the modelers, but like they say about tools "every tool has its use" and I look at glue as another tool.. the proper glue can make a world of difference.
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Old 04-17-2014, 06:25 PM
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Thanks for the link

Cheers Bob T
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