Hello I am embarking on a project to improve the concertina (a small accordion traditionally 6 sided) ergonomically, part of this is done by reducing the weight with carbon fibre components. The two components I am making are the ends and here is a picture of one of these ends, the components  are quite small at 200mmx120mm.  I am using resin infusion and the problems I am running into are dry spots, small bubbles and large voids (see images). I am using the large epoxy mould making kit and I have included an image of my mould. I have tried to push the bag around into every contour but still suffer from these problems. What would you guys advise?

There could be numerous issues with the process. But one thing ive noticed is that you have a very small radius in the centre to the 90degree walls. You need to ensure that the material gets right into the corner and doesnt bridge. You can use multiple plys in that area and when bagging use a dibber to prod the material into place prioe and post infusion to make sure there is material and not just resin in the corner

You should use a spray adhesive to lay down your layers of fabric, particularly the first one. There are special ones for infusion, I have used 3M 77 (sparingly) and it works fine. I tack down every layer including the peel ply like this.

I cannot stress how important it is to force the fabric into the tight corners in th layers. Use wooden/plastic blunt tools for this, fingers too. Really work it in. If there are voids when laying down, chances are they will remain as voids in the finished part.

Resin should be degassed completely before infusion.

The bag should be 100% air tight.

Also since the part is small, only open the resin feed a little and let the resin infuse slowly, that way avoiding dry spots.

These are some of the things I have learned and I have had a few perfect parts, I am a beginner still. But I had a very complex part to start with. eventually it works. It is a skill after all and needs to be learned.

cheers!

An alternative solution would be the use of ProFinish Carbon Fibre 2/2 Twill especially for the recessed bit. You could easily cut a neat square to fit in there.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant