Hi, first of all, big thumbs up for the easy composites team. Great tech. support, youtube, wepshop etc. you got me into trying carbon fibre. Well done!

I'm new to carbon fibre and just wanted to get some tips and tricks from more experienced doers. I have vacum bagging equipment and have been doing a few test just with plates on glass to get a grip on laying up wet and mixing epoxy, vacum, bagging and so on, I did one intake tube (not one a really need) just to learn and see how difficult it is and how to not do. I have a 3D printer so I will print molds and coat them with XCR epoxy+relese, the same way I did with this test tube mold.

What I learned was that you cannot do anyting with the inside of the tube if I put the bottom half on the table and then the internal vacum tube through. And thats ofcourse totally obvious after you have done it once , could only get the peelply on one half as I needed the CF parts to overlap and so on and so on...




But to the real project, this is what I want to build. A modular CF intake, that are in three parts + aluminum flange + throttlebody flange in alu. Three parts so I can make different lengths of runners and different size and shape of plenum depending on the case.

I was planning to bond with structural adhesive as you see with over lap of 7-10mm. Planned thicknes is now 2.5mm, is that overkill?



Any comments and thougths on bonding points and thicknes of the part?

When split in this way its also more easy to wet lay parts. maybe I'll try infusion later.

Anyone aware of 3D printer filament that can take the prepreg heating process?

/André

To be fair your parts have come out very well so far.  You might be able to skip the peel ply and just rely on a bit of release film.  Alternatively if you aren't trying to squeeze out too much resin, then just use the bag and it should rip out afterwards as the runners don't seem too long. 

The overlap seems fine.  Do you mean 2.5mm thickness over the whole plenum? Is it for NA or boosted?  NA that would certainly be very thick and you could easily half the thickness.

The two parts of the plenum itself look like you could infuse them no problem with careful mould design.  The runners would be very difficult to infuse.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

HI, thank your for your answer.

The last grams on weigth is not critical so no need to squeeze out epoxy if the strength of the part is about the same. I have perforated release film, so that could be one way. What about peelply+perforated release, in my head the release in that case would not have any function, am I correct?

It will be NA to begin with but later compressor boosted, maybe max 1.5bar so nothing crazy. Yeah I thought the thicknes could be 2.5mm over the whole but maybe thats unnecessary thick, feels like 1.5mm is thin but what do I know...I dont have any big flat surfaces so in that way the shape will add to the stiffness. The test runner is 200+400+400 and you can easily stand on it no flex at all, but thats a small diameter part.

What about adding layers to the inside after cured? Is that a good way of adding strength if I see it flexes or so? Is the way to go to add epoxy and layer directly to the peeplyed inside, or shoud I sand it to bond epoxy better?

A vacum question, my plates are now made with peeply+release+brether and 20% vacum. If i understood correctly I should not use more vacum i this case. But what about when no breahter is used like for the runner, any benefits of using more vacum when not having breather that takes out epoxy from the part?

/André

For NA 1mm is plenty.  You want thicker for boosted applications but its a bit more complex as shape will determine thickness etc. 

If you are struggling to get the bagging stack in place with the fabric overlap, you may struggle to add extra layers hence why you aren't using peel ply now?

You can certainly add extra layers internally afterwards just ensure you key the surface and thoroughly clean before you laminate.  That can be useful if you struggle with the joins as you can wet lay carbon tape over the joins.

Vacuum bagging in general, 20% vac is the starting point.  You can adjust it up and down to get the finish you want.  Too much extra vacuum will squeeze out too much resin leaving the part dry.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

hi.

ok, thanks. I think I go with about 1,5mm for runners and about 2mm for the rest then it will be enough.

Yeah, I had a hard time having peeply on both halves in my first trial, but I think I can get it done next time. I put the internal tube last, after I have put halves together and have peelply applied, then I put the inner tube through. Should be doable.

when you say key the surface, what process is that?

OK, so even if I have no brether that takes up exess through perforated release I could squeeze out too much from the reinforcement to the bag it self?

No thoughts on 3D printing filament that can take pre-preg owen temps?

Thanks again for your input.

/André

First mold in printer today. This is what it looks like, will be vacum bagged. It's split (not the way screenshot shows) in half and will be glued together, sanded, coated with XCR epoxy and sanded 600+1000+2000+vax.

Keying the surface is basically roughening it to help with resin adhesion - usually with sand paper. Typically 120 grit or coarser is fine.

Even without breather you could squeeze out too much with too high vacuum.  Its not as bad as it would just bleed onto the other side of the release film but you certainly could cause issues with too much vacuum.

Not aware of any 3D filaments suitable for use as a pre-preg mould.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

if your printer is capable of printing ABS, that material will remain stable up to 105c.  Could suffice for a low temp/variable temp cure/post cure.