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Vacuum bagging do's and donuts

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Foundationer

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Nov 29, 2016
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233
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London
**** autocorrect!

Anyway. I've a lovely tailplane mould ready to go. Layup is bagging film, Peel ply, carbon, 5mm PVC foam (stabbed all over to let resin flow to the breather from the otherwise sealed side), carbon, Peel ply, perf ply, breather, bag.

What's the secret to guaranteeing all this lies flat? I'm terrified of wrinkles! In the past I've done the outer skin and the foam in one operation, then the inner skin which works great but adds a day and a whole lot of extra work. Recently I've cut that step out but it feels more like luck than judgement has let me get away with it.

Image of new mould & of fin half that I got away with in a single use foam mould.
 

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wsimpso1

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Oct 18, 2003
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7,645
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Saline Michigan
First step to making it lay flat is bagging to the caul plate or to a sturdy tool. Pressure from the atmosphere pressing the part down against the mold or caul plate does wonders.

My cored wing skins work great laid up in one cycle - see my posts on this topic. My massive core control surfaces are done one side at a time. And my rather highly contoured fuselage skins should have been done in two or three bag cycles - I got some wrinkles that required sanding and patching.

If it takes two cycles to get good parts, smile and be happy you have good parts.

Billski
 

User27

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Joined
Apr 5, 2015
Messages
80
Location
England
The only wrinkles that matter are in the finished part ...
I would use more holes in the foam. Get a piece of plywood 6" square (size not critical) and whack in 1.5" or 2" nails at (say) 1" spacing. Use that to make holes in the foam. Make the first part from glass, and use it as a practice piece, then move on to carbon?
 
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