Well, I took the leap into the wide world of vacuum bagging on Friday night. I'm now not only a KBbbs addict, I'm also a vacuum bagging addict. At first, I used my shop vac, but I later borrowed a vacuum pump from a friend on Saturday. (I was worried about burning up my shop vac motor.)

I carved the blade mold from a piece of EPS (extruded polystyrene) building foam (Dow Blue board/OC Pink Board) and then covered it with glass. I used glass and phenolic microballoons to fair it out. (This has taken a few months as it wasn't a top priority)

I then waxed the mold and covered the waxed form with PVA. When the PVA dried, I brushed on epoxy, laid on a piece of fabric, and then 2-4 layers of biaxial cloth. I laid on more toward the tip, because that area receives the most abuse, and it also spans out beyond the end of the shaft.

I was able to keep the resin content down around the weight of the cloth, so the blades aren't resin heavy, and the cloth in the layup looks really cool!!

After wetting out with resin, I covered the wet glass with a sheet of saran wrap. I put the covered, glassed mold in a heavy clear bag with a couple old T-shirts for breathers along the sides and bottom of the form. I stuck the vacuum cleaner hose in against the t-shirts and drew the bag around the hose. The vacuum sucked the air out of the bag in no time, and removed the internal pressure from the bag. Atmospheric pressure began pressing in on the outside of the bag, forcing air bubbles toward the sides of the form where the air was sucked through the "breather" t-shirts.

I'm aware that using a directly applied peeler ply (nylon microfiber) and a breather ply over that would let me suck the excess resin out of the laminate, but I didn't have any scraps of nylon on hand. That would probably also have required making vacuum ports in the bag, and I wasn't feeling quite that ambitious!!

I heated the laminate through the bag with my wife's hair dryer (sorry honey!) so the epoxy kicked off after about 15 minutes and I was able to turn off the shop vac. I left the blade on the form and in plastic for another few hours to more fully cure, and then stripped it off the form--worked great! I trimmed the blade to shape, and I'll mount them on my bird's mouth shafts tomorrow or Tuesday night. (Just in the nick of time for R2K). Nothing like an 11th hour vacuum bagging effort before a Rendezvous, eh Grant?

Photos to come.

Shawn