this is the second attempt at this part, same problem each time, seems to have dry ares or air voids.

Wet-layup and then vacuum bagged is notoriously tricky to get rid of all imperfections, it looks to me like those pin-holes are caused by drying out the cloth too much, I would suggest lowering the level of vacuum that you are pulling slightly, you should find that this will reduce the problem.

Paul Statham
Easy Composites / Carbon Mods - Technical

Thats interesting, could you suggest an approx level?
I have tried quite a few experiments lately and always get a dry surface/ pinholes.

http://motoform.blogspot.se

Thats interesting, could you suggest an approx level?I have tried quite a few experiments lately and always get a dry surface/ pinholes.

In our experience, really quite low! - Try 1/2 bar or maybe even lower. You can also reduce the amount of perforation you're using in your release film - to do this you can use an Un-Perforated Release Film and actually then perforate it yourself giving you total control over how perforated it is.

Like everyone's mentioned, vac bagging is a trial and error process on every new part. It can certainly be 'got right' and will produce great results when you find the right balance of resin quantity, perforation and vac level but even for the best of us it's a trial and error process.
                                                    

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Matt
Thank you, I have started to think in these term and will try it, think I bought unperf last time.

Lets say I switch to infusion, how many layers of CF will it penetrate?
If you remember I make some motorcycle parts and amongst them a self-supporting rear unit,
seat-tank without a rear sub-frame.
In places the thickness will be 5-7 mm, will infusion penetrate all those layers of CF? (some UD fibers in there also.)
I guess the answer is yes with the corrects routing and blocking of the feed,
in that case is that expert stuff that I should practice until perfection, or straight forward?

http://motoform.blogspot.se

Lets say I switch to infusion, how many layers of CF will it penetrate?

Baja Patient is right, the resin will go through as many layers as you have in your laminate. Resin flows well through woven reinforcements (particularly twill weaves). I've never known a laminate too thick to infuse.

In places the thickness will be 5-7 mm, will infusion penetrate all those layers of CF? (some UD fibers in there also.)

The UD fibres won't infuse very well; they sit so tightly packed that the resin would find it difficult to get through. If you're using unidirectional carbon with infusion then you should use UD that has some weft (i.e. it is 90% UD with some glass or carbon running the opposite way, like a woven fabric but with the vast majority of the fibre running lengthways. UD in this format is particularly common as a tape (a strip of woven material between 100mm and 500mm).

I guess the answer is yes with the corrects routing and blocking of the feed, in that case is that expert stuff that I should practice until perfection, or straight forward?                                                    

Well, making a structual subframe itself is certainly not basic/beginner work but if you've designed it correctly, the actual infusion should not really present any problems that would not be encountered when infusing something less ambitious.

All the best with it,

Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Thank you.

http://motoform.blogspot.se