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Hanaldo
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Group: Forum Members
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Hey all, Thought I would just post up the latest project I have been working on; can always do with being told how to do it better. So the project is a 4" intake pipe for my R34 Skyline. I wanted to attempt making something from scratch, and given I only had a 3" intake pipe previously I couldn't use that to make a mould for this one. So I started off by using the centreline of my current intake pipe to make a 3D drawing with the dimensions and cross-sections that I needed. I also added 100mm to the straight section on the end, as I wanted to move the air filter further away from the exhaust manifold:    From there I was able to print out the cross-sections I needed, and transfer them to some 3mm balsa wood: 
Which allowed me to create the skeleton structure of the part: 
I then needed to in-fill the gaps, so I made some low density polyurethane foam using a 2-part pour in place system. With this being the product. I made 4 of these 'blocks'. 
Then I used this foam to fill in the 'body' of my part: 
Trimmed and sanded down to size, and voila! 
From here, I filled and sealed the part with epoxy resin filled with microballoons: 
Then used a stainless steel and fibreglass reinforced body filler to fill in the big gaps: 
Flattened it down: 
Then used the same filler to cover the whole thing, so I could fill in any low spots in the foam: 
Sanded it down again, then trial fitted it in the car: 
Perfect fitment to the mm! 
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
Visits: 28K
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Then did another layer of filled resin with a little bit of red pigment as a guide, so I know when I am rubbing through to the next layer: 
Well I was going for red... But I forgot that the microballoon powder is white... 
So I ended up with this aorta... 
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I only did a thin coat because the surface was already pretty good, so didn't need a lot of filling.
Then flattened that layer down and managed to do it without rubbing through (hazzah!), so have moved onto the high gloss coat. Filled the resin with calcium carbonate this them, then used a black pigment to show low spots better. 
Finished flatting it down, then sanded up to 2000 grit: 
And then polished up to a mirror gloss: 
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
Visits: 28K
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Then put the barriers on: 
Took that picture before I had put the locators on the flange, but that's alright. Then used Airtech Infusioncoat epoxy tooling gelcoat: 
Put the reinforcement layers on and then let it cure:
And then demoulded:
The reason it's not very glossy here is that I had applied 8 coats of Frekote 700-NC release agent, but it was my first time using a semi-perm and accidentally applied the coats far too heavy. Left me with some residue on the surface that wouldn't buff off, so I'll have to polish up the final part surface too.
Layed the carbon in:
Infusion stack completed and all bagged up: 
Aaand infusion completed and cured for 24 hours: 
This is where I am up to at the moment. I just need to post-cure for 4 hours, then I can demould to see how it went, so should have a finished half this afternoon. If it's gone well then I will infuse the second half tomorrow.
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Hanaldo
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Group: Forum Members
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Visits: 28K
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One thing I did do incorrectly, is I didn't bother sanding the ends perfectly flat. They got a lot of resin build up on them from being stuck down to my coreflute, so they were very difficult to sand. I sanded them so that they were level and almost flat, but didn't sand all the bumps and ridges out. I figured those ends weren't going to be on the final product anyway, their finish wouldn't matter too much. Of course when it came time to demould, I had some minor mechanical lock issues. I managed to get the parts out using high pressure water, but it would have been a lot easier if I had sanded them perfectly flat. Or even better, put a dome on the ends to give me a positive draft angle.
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carbonfibreworks
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Group: Forum Members
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Quality work Hanaldo. Chris
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Matthieu Libeert
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
Visits: 28K
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Thanks guys  It's taken some time, that's for sure. Flatting that plug down only to recoat it and do it all again was rather tiresome. But definitely worth it in the end. There was no damage to my plug in the process either, so I can make another set of moulds if I need to. Have got the second half all bagged up, just in the middle of the leak down test but it appears to be all good to go. First time I've ever had a leak free bag first shot! So will demould the first part soon to see if it's ok, then probably do the other infusion before bed. Fun times!
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
Visits: 28K
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Straight out of the mould: 
Has some residue from the Frekote on it taking the sheen off, so will need to polish it up. Also had an issue with bridging on the straight end:
Luckily that's not too critical, I can just make that end a couple mm shorter if need be. Thought I had paid close enough attention to pushing the material into those corners, but obviously not. Will be more careful next time.
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Toffee
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
Visits: 28K
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Thanks mate For anyone interested, the stack was composed of 2 layers of 199gsm 2x2 twill carbon, then strips of the same fabric placed at 45* either end for strategic reinforcement. Then an additional 2 strips of uni close to each end where the hose clamps will be placed, followed by a final layer of the 199gsm carbon over the top. The weight of the untrimmed part is 112 grams, and I can stand on it with no distortion.
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