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Building Tips and technical articles. => Building techniques => Topic started by: jim gilmore on January 29, 2009, 10:59:03 PM
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Ok, I'm a little confused here. I thought the recommended epoxy for doing engine mounts/wing joints fuselage doubles on a profile was a slow set epoxy, but when looking at my local hobby shop or even online all i am see is 5 min,6 min, 15 min,30 min aqnd 45 min. Arent there any epoxies in the 2 hour range ? Please be specific to product so I can get the rightn thing.... Thanks in advance.
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Everybody has their favorite brand but I use the Sig 30 min. 2 parts A to One part B. I'm sure there are 1 or 2 hr set up types but the 30 min. is just fine.
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The slowest I use is 30 minute. I add a little fiberglass or micro ballons to the mix too.
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I use West Systems epoxy (get it at the boat shop). I use 105 epoxy and then choose a hardener depending on what I'm doing. The standard 205 hardener gives you about an hour working time. There are others that are both slower and faster.
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I use WEST also. They have Fast, Slow, Tropical, and another hardener.
Neat thing is you can mix hardners to get in between times.
I find I mostly use Slow these days.
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Don't let it worry you so much. All epoxies and cure times work fine. Their tenacity and strength is way more than even rock hard balsa can fully appreciate. Just make sure you pick a cure window that gives you enough time to assemble and align parts first.
When I use epoxy for models I do 30 min structural epoxy (from Aircraft Spruce for building full scale experimental airplanes) because that's what I keep in my shop. It works for airplanes to kitchen sinks. Mix it, then heat to thin it out for better penetration, apply to parts, let sit a couple minutes to soak, reapply and put the parts together. If truth be known my 20yr+ old cl & rc planes built that way with plain old Duco show no problems either...which is highly contrary to what I read is supposed to happen. I suspect it's more about building correctly than type glue...
Bill P.