Because of its final elasticity, it does not sand well and beads. It also sticks to painters tape and is easy to pull out like caulk when removing the tape. Over the years I've learned to work with these downsides. I used Alene's glues for glassing because of tremendous cost savings. As much glassing as I do, I could buy a BNF plane with the money I'd spend on Foam-Tac. The downside of Alene's glues is that they are water soluble and this makes painting difficult with water based acrylics. There had to be something better out there.
A couple of weeks ago, I placed a big order to Hobby King. As always, I looked for things I might need but didn't know I needed them until I saw them. Worst than going to Costco, you always buy more stuff than you intended. I came across Bob Smith Industries Foam-Cure and every hobbyist has their epoxies and CAs at their bench. If they decided to make a foam glue, you know they would get it right. Foam-Tac is good, but it is a modified glue for making and mending clothes!
So on my current build I used Foam-Cure as a trial where I've had the biggest problems with Foam-Tac. I like to fill the fuselage nose gaps with foam strips and sand it smooth. These are parkjets, smooth equals less drag, more speed, and less downstream turbulence. Sanding Foam-Tac is like sanding the gummy residue left by a sticker and Foam-Cure is like sanding Bondo. Bonus, the fuselage nose cone built with Foam-Cure feels much more solid than the one with Foam-Tac. Score, it dries faster! The picture doesn't do justice to the difference in the sand-ability of the two products (Foam-Cure on the left):
Foam-Cure
Foam-Tac
Check out the price difference:
Foam-Cure from Hobby King $4.03 for 4 oz = $1/oz Same price Alene's
Foam-Tac from FRC Foamies $9.99 for 2 oz = $5/oz
Foam-Tac cost 5x Foam-Cure!!!!! For that price difference it should build the plane as well as hold it together!!
Stephan
Excellent post, Stephan, I look forward to getting some Foam Cure and trying it on a build in the very near future!
ReplyDeleteLike you, I find I use several different glues when building, epoxy, 3M Super 77, hot glue, etc, they all have their appropriate places. I built one plane completely with Foam Tac when I first got some and found that it does not hold up in certain areas like control horns and motor mounts, kind of important pieces to stay strong and secure... :) I ended up having to rebuild parts of the plane with epoxy after all my control horns and the motor mount started to loosen.
I noticed on the Bob Smith site you linked above, it stays flexible enough to use for hinges, so that is good news as well as that is a big consumer of Foam Tac on my current planes.
Thanks for sharing this find, will save a lot of money and it looks like some time as well..., both of which I could always save more of!
Cheers,
Scott
Stephan, I've been playing with Foam-Tac, trying to hide the glue inside joints or spreading on tiny amounts of spackle to make the surface sand-able! Both with limited success. Thank you for the post. I've used Bob Smith CA for years and will order up some Foam Cure soon!
ReplyDeleteDave,
ReplyDeleteI'm with you, you can't sand Foam-Tac its just too elastic in its final state. You will really like the sand-ability of Foam-Cure. BTW, this is not a paid endorsement!
Stephan
Sanding Foam-Cure.....whatever.
ReplyDeleteJohn,
DeleteWould like to expand on your experience sanding different types of glue when constructing foamies?
Stephan
Stephan, I was thinking of a simple way to compare strength and flexibility of FoamTac and FoamCure. I was thinking of mocking up something that roughly equates to a nacelle and wing. I'll glue one with each glue and then bend the wing until either the glue separates or depron breaks. Then, I've been thinking that FoamTac's characteristic of never hardening is a benefit for any surface that flexes so I was thinking of repeatedly bending the same nacelle-wing set up and seeing if FoamCure cracks under this "fatigue" loading.
ReplyDeleteDave
Dave,
DeleteYour testing mentality fits right it with our approach here at NAMC. On my present build, I used Foam-Cure on the filling strips and glassing. Next build I use it on the entire build and see how it does over time. The real testing will be done by Scott who has planes with over 200 flights! I crash my planes pushing limits way before they ever suffer from structural fatigue. That's why I fly foam, if you ain't crashing', you ain't flying, you're tooling around.
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ReplyDelete