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Jun 21, 2018, 10:10 PM
foam is fun, but glass is fast
Redfarren's Avatar
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Discussion

Joining half core PU filled wings and fuses.


Any recommendations on best methods for joining half core wings and fuses?
I filled and sanded flush a fuse and if I can get wing done I hope to join the halves tonight, I may wait to get a foaming agent for my epoxy depending on what you guys say.
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Jun 21, 2018, 10:31 PM
foam is fun, but glass is fast
Redfarren's Avatar
Thread OP
Sanded pic
Jun 22, 2018, 02:57 AM
myday.. myday
Thats looks like an interesting project. You can add foaming agent to the epoxy but it might not work exactly as you want it to, you can also make a rich blend of epoxy and microballoons of you want to use epoxy. Perhaps PU glue could be used (foams up and hardens with moisture).
Jun 22, 2018, 03:50 AM
Rock Breaker
gazasmith's Avatar
Cut a small groove all around edges and lightly sand composite skin to remove foam for best bond to skin. Mix some epoxy and add a 50/50 mix of fibre for strength and micro balloons for volume. Fill grooves with mix and smear a gin film of faces of foam. A grooved trowel is good for spreading mix on faces. Clamp or tape together.

Groove around edges is important to lick together skins. You also want a good join of foam faces for max strength.

Cut out electrics pockets before you join so much easier to shape pockets to match parts while it's in halves.

Only cut out just enough foam it adds heaps to the strength of the part.

Gaza
Jun 22, 2018, 11:33 AM
foam is fun, but glass is fast
Redfarren's Avatar
Thread OP
Thanks Gaza, I didn’t get my elevons finished so no guessing cg yet, drew some lines for the radio gear. Might not get to it for a few days tho, just found out good chance I’ll be headed out for an overnight/all day fishing trip as soon as off work this evening. Come on yellowtail!!
Jun 22, 2018, 04:17 PM
Registered User
Ward Hagaman's Avatar
One thing to consider with some 2 part foam systems is that some aren't super stable with heat. About 15 years back there was a a fellow molding DS wings with a Smooth-on product, but he had issues when he left the wings in his car, if I remember correctly. Andreas Mergener I think? Might be worth searching for his experiences If you haven't already.

Good luck with your project!
Jun 23, 2018, 05:17 PM
pnc
pnc
Registered User
pnc's Avatar
Check out Gaza's rockbreaker thread tons of great tips.
Ward is a smart cookie also he has done some outstanding work.
Pete
Jun 24, 2018, 10:52 AM
supreme being of leisure
ZAGNUT's Avatar
Quote:
Originally Posted by Ward Hagaman
One thing to consider with some 2 part foam systems is that some aren't super stable with heat. About 15 years back there was a a fellow molding DS wings with a Smooth-on product, but he had issues when he left the wings in his car, if I remember correctly. Andreas Mergener I think? Might be worth searching for his experiences If you haven't already.

Good luck with your project!
not just heat, atmospheric pressure also causes changes. once sent a model of a human foot made out of PU foam overseas, foam because it had to be light, and it shrunk down to about 2/3 its original size. i blame the low cabin pressure of the airline relative to where i am which is well below sea level.


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