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Smooth finished surface from vacuum bagging?


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OK so I bit the bullet and bought a vacuum pump, + all sundry accessories to vacuum bag the rudder and centreboards I made. 

 

Boards are made of cedar, perfect rift sawn old growth, all nicely shaped.

 

First off I layered up wee blank, 150x150 or so, a test of 8 layers of carbon cloth (200g12K), epoxied and vacuumed. Finished black had hefty imprint from the bleeder matting. Thought it might be from having a thickish layup of carbon. 

 

Launched into the rudder. With the above cloth, nicely vacuumed, followed all contours well, but still a strong imprint from the matting. bugger. requires sanding and finishing. 

 

So how do I get a smooth finished surface straight out of the bag? tried to do away with the bleeder matt but no dice.

 

sorry no pics - battling with phone. 

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Ah ok, good to know, just was wondering what I was doing wrong. 

 

not using peel ply as it's a finished article... 

I am using perforated film, and this grid mesh, https://shop.swiss-composite.ch/pi/Vakuumtechnik-Infusion/Fliesshilfe/SCS-Flowgrid-slow-125cm-180C.html

 

SCS flow grid slow

180.0606_kl.jpg

 

i guess I'd be better off with something like this. I'll just sand and coat the rudder to get nice finish.

 zzb100553_kl.jpg

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KM, What's your measure of "over-sucked"?

 

I can get to 0.05 Bar. Too much?

 

Also, did you do vacuum infusion (i.e. vacuum pulling the resin in) or just wet layup and then bagged?

 

Just thinking about it cause I'm going to do some foam work as well, and was going to try infusing.

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You should use the perf film to control the resin bleed (adds restriction into the system), and pull the max vacuum you can.

 

If you don't have restriction you can overbleed and get porosity

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