QuickTalk 7 - Q-TIPS
- Category: Q-Talk Articles
- Published: Friday, 31 December 1982 06:11
- Written by Jim Masal
- Hits: 1407
Here is a tip for making "no sneeze" dry micro. Put a measured amount of pre-mixed epoxy into a Zip-Lock sandwich bag. Then add a sufficient amount of micro. Eliminate most (but not all) the air from the baggie. If you eliminate all the air it takes longer to mix. Mash the hell out of the bag - taking care to mash the corners, too. Turn the bag inside out and collect the micro or cut one corner off the bag and squeeze out. This provides a better mixing method without the dusty mess. (Bob Falkiner, #2015)
Since I am installing the antennas described by Jim Weir of RST, Inc., there is quite a bit of shielded cable that has to be run through the foam in little troughs. This is frustrating as the foam has a tendency to ball up when digging it out. To relieve this, I made a little Hot Wire Trough Cutter. It's installed on a piece of scrap 2x4 using carpet tacks. Use the regular steel wire in a U-shaped form. The desired radius is formed by wrapping around a sample of the cable. To cut the wire channel, I draw a line on the foam core where I want the trough, heat up the cutter and move across. It provides a speedy, perfectly shaped cut. (Sam Hoskins, #2614)
The five-minute epoxy is easier to use if it is thickened by mixing in some microspheres.
Cut your stirring sticks flat on the ends and sand smooth. The square end gets to the epoxy in the bottom of the cups when mixing.
To prevent a squeegee from snagging the cloth during layup, round each end slightly with fine grit sandpaper. (Ron Cross, #2397)
I have finally freed myself from the Lava bars, MEK dips, soapy scrubbings, dirty lavatories and every other disagreeable thing associated with cleaning used epoxy brushes. Nor after making a layup, I simply wipe the excess epoxy out of the bristles with a paper towel and put the brush in a jar of lacquer thinner. Mash the bristles a couple of times in the bottom of the jar and let stand in the thinner overnight. (A little Saran Wrap and a rubber band keeps the fumes out of the workshop.) Since the epoxy won't cure at all, the fibers stay supple all the way to the handle. The next day remove the brush, shake out the excess thinner and let stand to dry. My oldest brush has just finished its 17th layup and is still in excellent condition.
If you have ordered Feather-Fill and let it stand any length of time, you will notice that the suspended solids settle out very quickly. You are left with incredibly thick clay at the bottom of the can and an almost watery top layer. The manufacturer recommends a mechanical mixer (one of those nifty attachments for your variable speed drill) and I couldn't agree more. The trouble is that you are likely to be wearing half the contents if you try using a mixer with a brimming full can. I found it easier to remove the can top and drill a hole in the middle, slightly larger than the shaft of the mixer. Thread the mixer through this opening and tap the cover back on the can. You can now mix the Feather-Fill without being splattered. A partially full can simply has a spot of tape to cover the small hole. You may find the bottom clay too thick even with mechanical help. To speed things along, place the can in some hot water while you are mixing. The solubility increases dramatically with temperature and will insure a quicker mixing time. Remember to avoid any open flame around the Feather-Fill. (Robert Herd, #478)
Our solution to the problem of post-curing the canard is illustrated by the photos below. We moved our construction bench against the wall of our shop so that we needed only four 4'x8' plywood sheets, some scrap lumber and some fiberglass blanket insulation to complete an effective closure. For a source of heat, we borrowed a portable forced-air kerosene heater (the type used on construction jobs). The hot air was ducted to the underside of the bench through a drainage tile to avoid applying the very hot discharge air directly to the canard. About an inch of space was left along the front and back edges of the bench to allow the heat to rise to the canard positioned on top of the bench. Five cooking thermometers were used on and around the canard to keep a watch on the temperature with frequent checking.
We decided to check for twist in the canard by attaching level boards mounted on two identical canard cross-section cutouts fastened to the canard about 10" inboard of the wheel fairings. With one end level - the other wasn't, so we bondoed the center of the upside-down canard to the bench and applied a corrective twisting force to the ends of the wheel fairings with scrap lumber and bondo to get each level board as level as possible.
It took about a half hour to bring the temperature up to the 130-degree mark with the heater discharge up against the mouth of the tile. Moving the heater back a bit from the tile kept the temperature from going higher. Frequent checking of the thermometers kept the temperature at the 130-135 degree range. Adjustments could be made moving the heater or changing the size of the openings at either end of the box. We kept the heat on for three hours and allowed a cooling off period. Our attempt at twist correction had been effective. Since we now had the setup, we also post-cured the main wing and corrected a slight drop along the outboard trailing edge. (Dick Howland, #2447)
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