July 14

July 14, 2005

The day from hell...

It happens - every thing is going peachy, then 13:00 sidereal time rolls around and everything goes to hell.

On Wednesday evening, I added some strengthening ribs to the one chain stay dome. I cut 1" wide x .5" high strips of Styrofoam and glued them to the top of the dome with epoxy resin mixed with fast dry catalyst. The plan was to add 2 or 3 layers of unidirectional carbon tape, but I could get the heavy stuff to wrap around the edges of the foam ribs. So, I tried my thicker 11 oz fabric, but it was also very hard to wrap around the foam strips. I cut out strips of my 5 oz fabric at 45 degrees to the weave and it worked perfectly. I added 5 layers, put the whole dome back into the vacuum bag and let it cure over night. The next morning, I peeled off the peel ply and blanket, and found a perfect and very strong wheel well.

So, I attempted to repeat the entire process and make the second chain stay dome. This time I used the thicker 11 oz fabric over the entire dome, 3 layers of unidirectional following the direction of the strength ribs, then I put the Styrofoam ribs on, and covered them with 5 layers of 5 oz.

I wanted this dome to be perfect so I even made a brand new vacuum bag. I inserted it into the bag, and that's when the Saturn transit happened.

First I couldn't get a decent vacuum. I tried everything, but the vacuum was still less than 10". Finally I made a second bag and placed the first bag into the second. I even taped up the edges with Duct tape for a double seal. I got a better vacuum - still only 19", but at this point I was willing to accept it. Then the freaking PETG dome mold collapsed.

ARGH!!!!!

When this happened with the first wheel well, we drilled a hole in the back of the plywood base and filled the mold cavity with expanding foam. It seemed to worked - at least 'something' about what we did seemed to prevent the PETG mold from collapsing and we naturally thought it was the pressure from the expanding foam.

Now that the mold was completely fill of hardened foam, I assumed it would be fine, but NOT SO.

By this time, a good hour or two (possibly even THREE since my first batch of resin was made) had passed and I knew my resin was starting to kick - time was of the major essence here. I tried a bunch of desperate fixes to the dome, but nothing seemed to work. That is, until my freaking vacuum started to suck again. Well, sort of problem solved there. Since there was only enough vacuum to softly press the blanket and peel into the resin rich cloth, the dome was no longer crushing in, so I figured I would leave it and hope for the best. There was enough vacuum to cause resin to get soaked up into the breather blanket, so at least that was good. There was still a slight indent in the mold caused by the pressure, but I hoped that it was small enough not to rub on the wheel.

After it had cured I had one HELL of a time getting the resin soaked blanket and peel off of the dome. It must have taken 3 or 4 hours - seriously!! I couldn't believe it. The layer was chipping off like hardened paint. If anyone has any tricks for ripping off peel ply - PLEASE let me know!!!! I think my problem ad to do with so many layers of carbon and so much epoxy. A lot of that epoxy got soaked up by the blanket and I think that's why I had so many problems getting it off.

Hopefully tomorrow will be a better day and hopefully this improperly cured wheel well will be strong enough to support a wheel. If it is strong enough, my plan is to build the frame with these chain stays as bolt-ons, then when I have time later on, I will remake either both of them or just this one and bond them directly to the frame.


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