Talk Composites - The Forum for Advanced Composites

Laminate/mold "free hanging" piece, between existing parts? (vacuum bagged)

http://www.talkcomposites.com/Topic22706.aspx

By Christian_83 - 2/6/2017 9:05:13 PM

Hi guys
Im modding my Carbon jetski hull, shortened it a bit. In this process i have to laminate/mold a new piece, were there is only air now.
The question is, is there some way to vacuum bag this in one process (maybe make a temp. backing plate or something) or will i need to lay 1 or 2 layers wet, let it cure and lay new layers on top of this and vacuum this?
The place i need to close is marked with the 2 red lines.
I thought about laminating from inside and outside. How ever, acces to the inside is very limited.

http://www.talkcomposites.com/Uploads/Images/b651cfd5-8895-4f5e-a04e-6e94.JPG
http://www.talkcomposites.com/Uploads/Images/96ea58ae-43cd-4756-acb9-e35b.JPG
http://www.talkcomposites.com/Uploads/Images/8144031d-4e78-475e-a965-c319.JPG
http://www.talkcomposites.com/Uploads/Images/0c5f557d-e971-47b6-be64-c26c.JPG
http://www.talkcomposites.com/Uploads/Images/be836350-b4ae-4853-8f31-76f9.JPG
http://www.talkcomposites.com/Uploads/Images/e9d50fbd-877b-45b9-9009-fa95.JPG
By Warren (Staff) - 2/17/2017 3:27:59 PM

In essence as the areas have no support on the reverse, it might make more sense to make at least a temporary mould behind where you are going to laminate and begin to laminate by wet lay technique.  Ideally if you can, tip over the jetski to get a good working angle.  A temporary mould could be as simple as some thick card covered in Flash Breaker tape glued in position, or a piece of metal shaped correctly and release coated - again bonded into place. 

To vacuum bag it, you would need a vacuum bag on the inside as well to be leak free. However you may want to put the bag over the top of the temporary mould surface. It could be quite difficult to get a nice sealed bag on the inside of a part like that but it should be possible. Remember you need a good surface for the gum tape to bond to, free from grease and dirt and also anything that could puncture the bag needs to be blunted.

On balance, a temporary mould and wet laying the first few layers would probably be the easiest solution. Once the new layers are cured and nicely sealed, you can carry on with a repair which you can vacuum bag on the exterior of the hull.