After making all the corrections in the plans, I was eager to get back to building. Steve had offered to come out and coach me when I started glassing the bulkheads, but after we got some rain (rare these days in Houston), it finally cooled down enough for me to work in the garage, and I got the bug to start right away. I had cut the glass the day before in an effort to do something to move forward, and I didn't want the cloth laying around too long gathering dust.
After spending hours rewriting the plans into a step by step checklist, I got so pumped up that I jumped right into glassing the back without doing more than glancing at them. Bad idea.
After the mess I had made from epoxy dripping around edges while doing the front side of the seatback, I decided to mask off the front side with duct tape before glassing the back. I put the seatback up on blocks to allow the glass to drape over the edges.
When I walked over to the epoxy cabinet, I was baffled as to why the light bulb inside wouldn't come on, until I realized that with temperatures in the 100s that day, the thermostat wouldn't be kicking on until it cooled down outside a lot more.
Building a metal aircraft like an RV has the advantage of allowing you to put down your tools almost anytime and coming back a few days later to finish up. With a composite plane, once you start a layup, you're committed. Laying up the back of seatback involves mixing up epoxy, micro, dry micro, and flox, so you have all sorts ways to screw things up if you're not careful.
I mixed up the micro to cover the seatback a little stiffer than the last time. It went on easily enough, although getting it around the big pores in the curved edges was messy. I mixed up some dry micro to fill in the gouges as well. I mixed up my first batch of flox using MGS. I was having a heck of a time getting the flox into the flox corners with the mixing stick before I remembered the builder's hint of using a baggie to squeeze it out. I ran inside the house and asked my wife to grab one for me since I still had my sticky gloves on. I scooped the flox into the bag, cut the corner, and marveled at how easy it was to squirt the flox into the crevices...until the baggie broke open before I was halfway down one side of the seatback. I was wondering where I could find a stronger bag when I remembered that I had bought a whole box of cake icing bags from Spruce with the first order. I found the bags, cut the hole in the tip, and the rest was fairly easy. The cake icing bags are a lot stronger than the baggies, so I was able to squeeze away without worrying about them busting open. I used the mixing stick to push the flox deeper into the crevices when needed, and I was able to get a pretty smooth flox surface.
While visiting Steve, I noticed that he used masking tape to anchor the edges of the cloth and keep the weave aligned before cutting it. I had thought this was a little excessive, but I think I'll be doing it from now on, since getting the plies to run straight is tedious at best especially after laying them down on some wet micro. Pulling on the edges of the cloth to straighten it out does work, but finding the opposite side of the thread is not so easy. I ended up pulling the cloth out of shape before I found the right thread to pull on. It took two plies of BID to cover the seatback since the roll isn't wide enough to cover it with a single ply. I was pretty pleased with how straight the second layup was until I noticed that the overlap between the two plies was one inch in one corner, but three inches in the other corner. After pulling it up again, I was able to get it a little more even (I thought).
Getting epoxy on the rounded edges without most of it running down the sides was getting me exasperated until I finally gave up on using the squeegee and just used my fingers to spread the epoxy around (still wearing gloves, of course). I scissor trimmed the excess, then started cleaning up. Whew - all done!
As I was walking out, though, I gave the layup a quick look and was surprised to several air bubbles and dry spots - I had forgotten to do the final inspection before putting everything away! I donned another pair of gloves, grabbed a work light, and went to work getting rid of the bubbles. The squeegee wasn't working too well since the layup was starting to set, so I simply flattened the bubbles by pressing my fingers against them. I don;t know if it's the epoxy, the foam, or me, but the glass did not seem to want to make full contact with the foam everywhere.
After that little faux pas, I thought I might want to peek at the checklist again. Peel ply? Oops. Luckily, I had cut it to size ahead of time before setting it aside and then forgetting about it. After mixing up another batch of epoxy, I applied the peel ply around the edges and over the overlap between the two plies. I then laid wax paper over the layup and put some weights on top, making sure they were placed over the wooden blocks the seatback was propped up on.
I was hoping to get some photos during the layup, but after my camera gave me a "Insert SD card" message, I realized that my SD card was somewhere in the house and I wasn't going to have time to go look for it.
After church the next morning, I came home and went straight to the garage to inspect the seatback and trim the excess. The MultiMax does a great job of trimming the wetted out glass, but doesn't cut well on the unwetted fiberglass at all, so I had to switch to the sanding attachment to trim that off. I used the long sanding bar to get the sides even.
I wasn't too disappointed in the result, but there were some areas I wasn't too proud of. It didn't look that bad until I took it out of the shop an into the sunlight. Yikes! I had what looked to be a big dry patch where the two plies had overlapped, and some parts of the layup had separated from the foam as well. I'm going to have to get another trouble light - I didn't see that at all with the light I have. One advantage the Aeropoxy had over MGS was that with its brown color, it was easier to see the spots that needed more epoxy. With the MGS being so clear, it's hard to tell where its making contact and where its not.I also found a few spots around the corners where the epoxy didn't quite make contact. I probably should have held off on the side cutouts until the layups were finished. Another lesson.
I carefully marked the center cutouts and double checked which angle to cut them at before cutting them out with the Multi Max. I think I probably should have peel plied around this area as well, since it's going to get joined to something later.
No comments:
Post a Comment