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Old Sep 03, 2012, 01:23 AM
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Australia, NSW, Wagga Wagga
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Hey Andrew, when you do a fill and close job, do you spread the foam on both halves of the mould or just one?
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Old Sep 03, 2012, 04:45 AM
AvB
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Josh, absolutely 100% definitely all over the surface of both halves. That's critical.

Hey I had an idea today, for making more advanced wings like DS wings that need spars and aileron stiffeners. What if we did the same thing, (full smear over both inside skins) and then lay a full sized piece of mylar over one mould half (with holes cut around the joiner pin areas) then close and clamp the mould? Then when it's cured, split the 2 halves apart and pull the mylar out. If it works, you'll have both halves fully foam filled, but perfectly flush fitting with no trimming required, and you'll reap the benefits of the internal back pressure giving good density under the skins.

At your leisure, mark out and cut trenches for the socked spars and stiffeners etc and test fit them to make sure the mould closes OK. Also dig out a cm or so back from the LE's and tips and clean up the very back edge of the TE too. Then when ready to finish it, do as I did with my light blue foam cored Scratcho ... wet up the socked spars. Mix up some Ampreg and put a band of it around the edges, a bead along the TE, some dribbled into spar slots and some smeared over the flush fit surface. If you don't have Ampreg, maybe a thinner splooge edge, and just epoxy or PU glue to join the main surface and TE. Then close and clamp and cure for a day or 2. I think this is the best of both worlds and can't wait to try it!
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Old Sep 03, 2012, 04:58 AM
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Great idea Andrew! Man you think up some good stuff!
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Old Sep 03, 2012, 05:14 AM
AvB
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Yeah nah yeah nah ... should be working not thinking about this stuff. But you could even use 2 bits of laminating film between the moulds (shiny sides out). Or maybe just Glad Bake greaseproof paper.
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Old Sep 03, 2012, 12:15 PM
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You could make 2 separate flat lids for the mold halves so they are assured to be flat. I think the mylar might bend around too much. That's another way I had planned out this process but my current wing mold won't work thanks to the geometry.
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Old Sep 03, 2012, 03:01 PM
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I like it Andrew!
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Old Sep 03, 2012, 05:08 PM
AvB
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Troy, I'm thinking that it doesn't matter at all if the mylar bends. It's going to be a perfect mating of the 2 halves, even if the join is a bit wavy in the middle. Irregularities in the surface won't affect the placement of spars etc.

I've been dreaming up a "wing in a day" video. Get a bunch of guys, paint the mold early, lay up soon after using fast resin, vac bag and hot cure for a few hours, unwrap and trim it, do the 2-side fast PU smear and close mould. By sunset you could pull out a finished wing! Would be quite fun and we could film the method close up.
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Last edited by AvB; Sep 03, 2012 at 05:14 PM.
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Old Sep 03, 2012, 05:11 PM
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If you decide to pour in the foam then cut it off, dont do what I did yesterday and scratch your mould with the saw! (through the tape)
Need to go and buy a smoother saw!
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Old Sep 03, 2012, 07:02 PM
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It will be interesting to see how it works. I should be getting my wing ready for foam this week. I'll be trying 6 pound foam for a slope wing. I have carbon caps but no shear web.
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Old Sep 03, 2012, 11:08 PM
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Quote:
Originally Posted by Troy View Post
It will be interesting to see how it works. I should be getting my wing ready for foam this week. I'll be trying 6 pound foam for a slope wing. I have carbon caps but no shear web.
That's about what I would need too Troy. What is the product details please?
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Old Sep 04, 2012, 12:00 AM
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Whats the story with sparying some water on the foam to get it to foam up more? (like PU glue). I found the foam Im using doesnt foam up a great deal so I gave it a spray and now its foamed up like mad but now Im thinking the density will be really low. I guess I'll find out soon.
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Old Sep 04, 2012, 03:53 AM
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Australia, SA, Normanville
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Quote:
Originally Posted by josh18 View Post
Whats the story with sparying some water on the foam to get it to foam up more? (like PU glue). I found the foam Im using doesnt foam up a great deal so I gave it a spray and now its foamed up like mad but now Im thinking the density will be really low. I guess I'll find out soon.
Which foam is it josh, The AMC stuff I use I very vigorous. Have you kept the lid tight on the tins if not it might have gone off, With mine 4 gram of each component and It overflows a 175ml mixing cup
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Old Sep 04, 2012, 04:03 AM
AvB
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Yeah same with the GP330. If you mix equal parts in a cup it foams like mad within 90 seconds. No need for water.
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Old Sep 04, 2012, 06:49 AM
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Australia, NSW, Wagga Wagga
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Its the rfoam100, maybe it has gone off- I didnt think of that. I know it was colder than it was supposed to be. I will warm it up to 35*C next time like it says. this time I was too impatient!
Anyway, some water (very little) sprayed on after spreading it out seems to kick it off really well and not affect the hardness but too much and it sets very spongey- I had to dig that bit out and start again.
Anyway, moulds are joined and we'll see how it goes tomorrow.
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Old Sep 04, 2012, 08:13 AM
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emufingers's Avatar
Australia, SA, Normanville
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Here is the tech dsata sheet for RF 100

http://www.barnes.com.au/catalog/foa...am-p-2252.html
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