+x

 

benji82 - 10/28/2019 12:55:02 PM

Did you get anywhere with this? I'm keeping an eye on this thread as this would be handy for me, too. I have been looking at making some moulds to by hand that I can use in my autoclave for prepreg parts.

Laminating glass by hand isn't too bad but carbon is a little more difficult as you can't really see the trapped air.

When I spoke to EC a couple of months ago, they suggested using a vacuum regulator so that you only pull 20% vac on the bagged part. I guess that full vac would almost mean that you are degassing the resin once it is in the part.

I've done a lot of GRP work and a lot of prpreg work but not much in between. Like I said this would be handy for me, too.

Cheers

Ben

+x

 

smp4616 - 10/28/2019 12:59:38 PM

+x

 

benji82 - 10/28/2019 12:55:02 PM

Did you get anywhere with this? I'm keeping an eye on this thread as this would be handy for me, too. I have been looking at making some moulds to by hand that I can use in my autoclave for prepreg parts.

Laminating glass by hand isn't too bad but carbon is a little more difficult as you can't really see the trapped air.

When I spoke to EC a couple of months ago, they suggested using a vacuum regulator so that you only pull 20% vac on the bagged part. I guess that full vac would almost mean that you are degassing the resin once it is in the part.

I've done a lot of GRP work and a lot of prpreg work but not much in between. Like I said this would be handy for me, too.

Cheers

Ben

no, I'm thinking vacuum bagging with wet layup doesn't give good results.  prepreg is different because you evacuate all the air and then compress the laminate in an autoclave, as the part heats, the resin flows out of the fibers and into the voids.  with wet layup, you pull vacuum which does clamp the laminate to the mold, but it also causes any air to expand, leading to larger voids, without some other force (autoclave) there to squeeze those voids out and into the breather, they're going to remain as the resin cures, leading to pinholes and voids.  

+x

 

benji82 - 10/28/2019 5:59:25 PM

+x

 

smp4616 - 10/28/2019 12:59:38 PM

+x

 

benji82 - 10/28/2019 12:55:02 PM

Did you get anywhere with this? I'm keeping an eye on this thread as this would be handy for me, too. I have been looking at making some moulds to by hand that I can use in my autoclave for prepreg parts.

Laminating glass by hand isn't too bad but carbon is a little more difficult as you can't really see the trapped air.

When I spoke to EC a couple of months ago, they suggested using a vacuum regulator so that you only pull 20% vac on the bagged part. I guess that full vac would almost mean that you are degassing the resin once it is in the part.

I've done a lot of GRP work and a lot of prpreg work but not much in between. Like I said this would be handy for me, too.

Cheers

Ben

no, I'm thinking vacuum bagging with wet layup doesn't give good results.  prepreg is different because you evacuate all the air and then compress the laminate in an autoclave, as the part heats, the resin flows out of the fibers and into the voids.  with wet layup, you pull vacuum which does clamp the laminate to the mold, but it also causes any air to expand, leading to larger voids, without some other force (autoclave) there to squeeze those voids out and into the breather, they're going to remain as the resin cures, leading to pinholes and voids.  

I do agree with all that. I was just saying that it would be good to know how to get a nice finish (pinhole free) using wet lay and vacuum bag. I'd like to make good moulds using this process which I can then post cure for autoclave use later on. At the moment, I'm guessing that high temp gel coat would be the way to go for me.