Chapter 14 - Section 6

Spar Cap Lay-up


This is the key session that your smooching (per my prior warning) pays off... 


Cutting the Spar Cap Glass Tapes

This section requires 23 layers and 17 layers of glass on the top and bottom spar cap trough respectively. Various Cozy builders used a variety of methods to keep track of the number of plies being added throughout the lay-up process. Rumor had it - some builders even ran out of the 3" glass tape mid-stream. To avoid both of the problems, I decided to pre-cut the glass tape to length ahead of time and line them up along side the center section spar. So...when I used up all the glass, I am done!


Instead of building a dispensing fixture for the tape, I just mounted the roll of glass tape on my adjustable work table (left). Stick a paper tube through the center of the roll. Add a couple of c-clamps to confine the paper tube movement and it worked just fine. I used masking tape to tape down the glass ends - centered at the cut point (before trimming) so that they don't fray. 


[Hindsight] It turned out to be a pain to remove the masking tape later. I would recommend to tape it AFTER the cut point, so that you can just cut the taped ends off entirely before use. A little wasteful, but well worth it. As for the longest tape, cut it to at least 138" (or measure it out first) instead of 135"+ per plan because I ended up a bit short and had to do a little bit of 'patch up' later on.


I also built the fence to keep the glass tape in place per plan. I used hot glue to hold the fence and its support beams in place. Then I added some dry flox along the rounded corner (of the foam) at the base of the fence to keep epoxy from seeping down the fence (from Wayne Hick's site). Recognizing it will be a time consuming step, I started about 10 am  - Susann joined forces after an hour or so. Mother nature was flexing her temperament a bit that day and our room temperature plummeted to about 52oF. My little space heater could barely keep our enclosure tent above 60oF. With the hair dryer at max heat, it took us 12 hours to complete the top lay-up plus peel plied. I had to build a small heat tent to make sure the glass cured properly through the night. I repeated the same on the bottom spar cap the next day.


After both spar caps were done, I removed the fence and rounded off the edges with a 3/16" router. I also spent a fair amount of time to remove the excess flox that leaked past my fence onto CS1 surface.






A couple points need mentioning here:

- When I stacked up the pre-cut glass tape, they looked thick. It seemed there was no way I could fit them within the thickness of the trough. So...I was pretty aggressive in removing excess epoxy throughout the lay-up process. When it was completed and cured, it turned out my trough level was about .06" too low . Remember, I added .06" to the depth of the trough earlier? I ended up adding 4 more plies to the trough later on to fill in the gap. One good thing about adding the extra layers is that it smoothed out most of the 'steps' on the tape surface and I probably have one of the strongest center section spars in town!     

- The spar tape soaked up LOTS of epoxy. Therefore, make sure you have plenty of epoxy on hand before you start.

- A hair dryer is much needed if you do not want to spend 20 hours on this step.

- Make sure your fence is tight against CS1 to contain the spar cap tape. I ended up having to sand them flush with CS1 surface. I may not have to do so, but I did it anyway.