Builder Hints
October 1979
Engine baffling - Lyc 0-235. When you cut your baffle material out according to Section IIC errors exist leaving the aluminum pieces short in some areas. Leave the Baffles about 1" too large, then trim to fit cowl. Leave 1/2" gap between the edge of the aluminum baffle and the cowling on trim before installing the rubber.
John Harris recommends a large farrier’s horseshoe hoof rasp for shaping foam, roughing glass etc. We have found an excellent substitute for sandpaper in the form of a Disston Abrader (course #401C) available at most hardware stores. Aircraft Spruce is now stocking the 401C. It is a long-life abrasive tool that’s excellent for shaping curved fiberglass edges.
We recently tried a new product that is a big time saver. It is an acceptable substitute for dry micro in the finishing process. Stitts micro-putty (MP 1100) available from: Aircraft Spruce and Wicks. This is a polyester - based material similar to Bondo, but 1/3 the weight, cures in a few minutes and works and sands similar to dry micro. Caution: do not use on blue foam.
Steve Briggs found an excellent method of setting wing incidence. While wings are still in the jig, on the table (both root and tip water lines level) Bondo a Stanley line Leveler (available at most hardware stores @ approx. 1.60 each) to the outboard edge and parallel to the butt line of you WA-1-1 wing fitting. Check that the root and tip water lines are level and that the Stanley is level before removing wing from jig. Use this level later to adjust wing to center spar (replaces the Bondoed board, from CP #12 page B).
A finger tip saver when finishing Featherfill through final color coat, use a sponge with sanding material bonded to it, sold at hardware stores as Quicksand/Auto Wetdry, Meduim/course.
Nat Puffer sends this idea to check your epoxy balance for accuracy. Simply put 20 nails in the hardner cup and 100 nails in the resin cup, or for the new Safe-T-Poxy system, 43 nails and 100 nails. Nat says it works great.
For those of you having difficulty drilling the 8 holes in each wing fitting, F.J. Wells recommends a Stanley drill Guide # 04-413 glued to the WA 1 fitting with beads of hot melt glue. Produces excellent, perpendicular holes.
Jake Bach reports that he modified his Michael S Engineering ratio pump per CP 21 and got 39-100 instead of the desired 43-100. He then switched the pivot from the left to right (hardener piston greatest distance from pivot) and that put him right on the money. We don’t know why his pump is different than ours, but we caution you to be sure to check your ratio if you modify your pump - pump into two cups and check on a balance scale.
Don Yoakam reports that if you update from old to new style Rosehan brakes, be aware that toe-in may change. The backing plates are rough castings and may not attach in the same position.
Sam Cochran made a carb heat valve using two Campbell soup cans covered with two plys of B.I.D. His has over 100 hours with no wear or