Q1 Plans Chapter 3 Page 3-23
- Category: Quickie Plans
- Published: Tuesday, 28 October 2008 01:00
- Written by Dan Yager
- Hits: 3724
Rip this page out of your plans and staple it to the wall of your shop. While it is a handy reference, it's still a good idea to read all the words in the eductaion chapter once in a while. Don't skip the details - they're all important.
URETHANE FOAM SHAPING
BASIC TOOLS: Sharp butcher knife, sanding block, surfoam file, wire brush and blocks/scraps of urethane. Use a dust mask. Hack away. Have Fun.
HOT WIRE CUTTING STYROFOAM
Hot wire tool has two lengths: 62" and 43"
Wire must be tight. The adjustable voltage control is best, but the job can be done with 2 12-volt, 6-amp battery chargers or a 12-volt car battery. Foam block must be well supported and weighted. Templates must be nailed on tight. First cut the basic block to size: this determines the planform size and shape. Level the template level lines: this determines correct twist. Set hot wire temperature for about 1" travel through the foam in about 4 to 6 seconds with light pressure. Do the actual cutting at about 1" every 6-7 sec. (8-10 sec. around the leading edge. Practice on scraps first.
BASIC LAYUP PROCEDURE
1. PREPARATION: Ply 9 or gloves on hands, shop temperature 75° ±10°
2. CLOTH CUTTING: You can get by with just a standard pair of good fabric scissors, but the job is much easier with the large pair of industrial scissors. (Weiss model 20W). They're $20 (gulp!) but worth it in the long run.
3. SURFACE PREPARATION: Foam - Hot-wire-cut surface needs no preparation. Sand ledges or bumps even, fill holes or gouges with dry micro immediately before the layup. Brush or blow away dust.
Glass - Always sand completely dull any cured glass surface (36-grit or 60-grit sandpaper). Resand if it has been touched with greasy fingers.
Metal - Dull with 220-grit sandpaper.
4. MIX EPOXY: Follow all mixing steps shown on your epoxy balance. Mix two minutes, 80% mixing, and 20% scraping the sides and bottom. Don't mix with a brush.
:Micro Slurry - Approx equal volumes of mixed epoxy and microsperes.
:Wet Micro - Enough microspheres for a "thick honey" mix.
:Dry Micro - enough micro so it won't run
:Wet Flox - Thick, but pourable mixture of epoxy and flocked cotton
APPLY TO SURFACE:
Layup over Foam - Brush or squeegee on a thin micro slurry layer (Thick over urethane)
Layup over Glass - Brush on a coat of epoxy.
5. LAY ON CLOTH: Pull edges to straighten wrinkles. If working alone on a long piece, roll the cloth, then unroll it onto the surface.
6. WET OUT: Don't slop on excess resin; bring epoxy up from below with a vertical "stab" of the brush ("stippling"). Start in the center and work out to the sides. Most of the time of a layup is spent stippling. Stipple resin up from below or if required, down from above. "NOT WET, NOT WHITE>"
7. SQUEEGEE: If you have excess resin, squeegee it off to the side. Use Squeegee with many light passes to move epoxy from wet areas to dry areas.
8. PRELIMINARY CONTOUR FILL: Save sanding by troweling dry micro over low areas while the glass layup is still tacky. This is done at trailing edges, spar caps, or over any low areas. The low places are over filled with micro then sanded smooth after full cure.
9. KNIFE TRIM: Save work of sawing and sanding edges by razor trimming the edges at the "knife trim stage" which is about 3-4 hours after the layup.
10. GENERAL INSPECTION: Take a good look for dry glass, excess resin, bubbles, and delamination before walking away from your wet layup.
11. CLEANUP: If you've used Ply 9 skin barrier, you can get all epoxy off your hands with soap and water. Epocleanse is also excellent for for removing epoxy and it returns natural skin oils. Brishes - rinse twice in MEK and wash with soap and water. Throw away after two to four uses.
MINIMUM RADIUS FOR GLASSING OUTSIDE CORNERS
QUALITY CONTROL CRITERIA/REPAIRS
See the Eductaion section