SV Carbon Tank project for Zoran

[tygaboy]

Kevlar is tough stuff. And even when it's saturated with epoxy and allowed to cure, it 'fuzzes' when you cut it. That is, you can't get get a nice clean edge. This is problematic when you consider that we have to cut a hole in the top to accommodate the gas cap. The last thing we want is kevlar fuzz poking out around our gas cap...So what to do?
How about eliiminate that issue by not including kevlar where the gas cap is going to be? OK, sounds good to me! One "hole-in-the-kevlar" coming up.

 

[tygaboy]

OK, so I'm a bit out of order with this pic, give me a break...
Carbon is getting REALLY expensive - when you can even get it. So it's important to plan ahead when laying out the patterns to keep waste to a minimum.
Pictured is the complete set of paterns for this tank. I flip each of the smaller 'side' pieces to make my rights and lefts while the big middle top piece gets placed smack center.

 

[tygaboy]

Considering I had 21 carbon pieces to cut, and this is all I 'wasted', I think I did OK...

 

[tygaboy]

Since we're vacuum bagging, it's important to be sure there are no 'sharp pokies' that might create a hole in the vacuum bag. Trust me, chasing vacuum leaks is less fun than you might imagine. And it's tough to find all but the most obvious ones. So as an insurance policy, I thought I'd try something new. I hot glued an old towel to the outside of the mold! Then I wrapped the flange and flange bolts in breather material, secured it with a bit if duct tape and, other than that fact that it looks like a circus bike gas tank, I think I've prevented any possible punctures that may have been caused by a stray 'glass fiber on the outside of the tank.
I've already waxed and pva'd the mold so I'm ready to lay up and bag.
Later this afternoon (with a bit of luck) I should have pics of our production SV tank top piece layed up, in the vacuum bag, under vacuum and curing.
Cover me...I'm going in...

 

[tygaboy]

I've goo'd up the mold with epoxy but this time, since we're going to bag it (and laying up a tank top takes for friggin' ever), I'm using a 'SLOW' hardner in the epoxy. It gives me about 3 times as long before it kicks and starts to gel/harden.
So, in this pic, I've already layed in the first two layers of carbon and what you see here is wetted out layer # 3 - the kevlar. Note the hole for the gas cap...

 

[tygaboy]

And here we are with all the layers in:
2 carbon
1 kevlar
1 fiberglas
1 carbon

The pieces overlap quite a bit and I move each layer's pieces around a bit to take as much advantage of the overlap as I can. So while this is a 'five layer' schedule, in many - maybe even most - places, the tank is actually up to 10 layers.
And for additional insurance, I added another layer of kevlar in the 'shoulders' of the tank. In the event of a crash, that's the most likely impact spot.

 

[tygaboy]

Here, I've layed in the peel ply and the breather layer. Duct tape to the rescue again to help hold everything in place so I can get it all into the vacuum bag without things moving out of place.

 

[tygaboy]

It's 'in the bag', baby!
Under about 20" of pressure until it's cured. We may just have ourselves a tank top tomorrrow about this time. Until then, enjoy!

 

[nafets]

 

[tygaboy]

Yowza! Started my morning with a bit of the ol' 'part popping'. What a great way to begin a Sunday...
The towel I glued to the mold worked great for preventing any stray fibers from creating leaks in the vacuum bag but was problematic when it came to seeing where the part had yet to release from the mold. Oh, well. Just bonk with the rubber mallet a bit more and pry with the plastic putty knife as before. Before you know it..POP! Ladies and gentlemen, may I present Zoran's Carbon SV tank production top piece. Mmmmm carbon....

 

[tygaboy]

In these pics, you get a good clear view of how important/visible the individual pieces in that outer layer are to the overall look of the tank. Again, if it was to be painted - no matter. But the nicer it looks, the nicer it looks. Now that I've built a part with this mold, I have a better idea of how the fabric actually fits. If I were to do another one, I think I'd modify my patterns a little bit and I think I could get a nicer look. But I'm happy with this as an initial result.

 

[tygaboy]

Here's one of the underside/inside. I have yet to do the final trimming and you can see where some of the breather ended up sneaking by the peel ply and getting bonded to the top. Again, no matter as that'll all get trimmed away.
Also, not sure you can really tell but the area just around where the gas cap will go has a final layer of fiberglass. Why? As I understand it (don't ask me why/how - I don't know) carbon and aluminum react at some level and over time, can 'cause problems'. The solution is to insulate the gas cap from the carbon with this layer of 'glass.

 

[tygaboy]

And here's a pic of a rough trial fit of the underside to the top, just to give you an idea of how the lip/edge of each part will serve as the bonding area for final fitment of the underside.
So, today I hope to get the petcock boss and gas cap installed. Then it's on to the venting system. After that we seal this up, add the mounts and deliver it to Zoran.
In all, the postings from here on out will be 'new things'. What I mean is that you've seen me make the same parts two times - once for the plug and again for the production parts. Thanks for your patience - it's on to exciting new stuff.

 

[BaSSiUsMaXiMouS]

 

[tygaboy]

Thought I'd start with the petcock mount. Since this is a race tank, we won't be using the fuel level sender but the process for installing the mounting boss would be the same as what we're doing here.
You can't really see it but remember that when I made the plug, I made a little indentation in the part so the mold would leave a mark right where we want the mounting points for this to end up. Here, I'm just illustrating where it'll go. And yes, I know i'm holding it backwards....
You can see I've Sharpie'd the cut out on the tank bottom piece...

 

[tygaboy]

But how to actually mount the petcock? Well, how about we go back to the original donor tank and cut out the factory mounting point. OK, great idea! Here's all we need...

 

[tygaboy]

A little Grindy McGrind with our Dremmel and we have a nice set of openings in our top and bottom.
I make the opening in the bottom piece a bit larger as the actual fitment of that part to the top may require some 'scoot it this way or that' to get the best fit and we may need the clearance, Clarence.
And REMEMBER TO WEAR YOUR PROTECTIVE GEAR - breathing and eyes - when sanding carbon!!!
And use your shop vac to suck away all that nasty dust.
Anyway, here's the end result with the bottom piece trial fit. Oh, I already trimmed the inside edge of the top part to ensure the bottom piece fits where we want it to go. We wouldn't be cutting for any detail component fitting before we knew how the top and bottom would fit together.

 

[tygaboy]

And here's what I use to do this sort of bonding. It's a filler that get's added to the epoxy to thicken it up. It is suitable for filling any gaps that may exist when bonding parts together. We'll use this same stuff when we bond any parts, including the top to the bottom.

 

[tygaboy]

Add as much filler as needed to get the desired consistancy. Me, I like creamy peanut butter!

 

[tygaboy]

Apply the cream filling to the inside of the tank, just around where we want the part to bond, fit it and clamp it in place.
I will come back once this is cured and apply a layer or three of carbon fabric to sandwich the mounting plate into the tank top.
A peanut butter, cream filled sandwich on a plate!
What could be better?

Once this is cured, it's on to the gas cap.