The following article is taken from the AMA National Newsletter.
Please see bottom of page for contact information.
This article is by Keith Kern from Tri-County Barnstonners.

GROMMETS, NYLON FLANGED SLEEVES, AND TUBING

It's the little things that make your model stand out, not only to the "seasoned builder/flyer" that may be looking over your plane with a "microscopic eye," but also to the casual observer.

Some "finishing touches" not only add to the cosmetic appearance, but are quite functional.

Almost always, there is a need for a hole, be it round, square, oblong, etc., somewhere in or on a model airplane. Probably the most obvious, is the cowl. Whether it is ABS or fiberglass, the necessary openings are subject to cracks and breaks due to the inherent vibration of engines and the stresses of flight.

One way to combat this problem is as easy as installing a rubber grommet, nylon flanged sleeve, or piece of fuel or rubber tubing in the drilled or cut out opening.

The rubber grommet is best applied to drilled holes such as openings in the cowl for the carberator adjustment needle or to reach the glow plug. Another place that they can be used is where the antenna exits the fuse to prevent chafing of the insulation and a most unwanted break. These grommets come in a variety of sizes, both outside diameter and inside diameter, and can be found at almost any auto parts house or Radio Shack. The grommets from Radio Shack are bagged with about four or five sizes and several of each size. If you go to an auto parts store, you will probably be faced with looking through a maze of bins and picking out each individual size. No big deal, but it can be aggravating at times.

The nylon flanged sleeve is really a nifty little item that I just happened to find at the local builder's supply. They are located in the hardware section with the nuts, bolts, and screws. By the way, you will also find nylon machine screws and nuts from 6-32 through 1/4-28 in this section. The flanged sleeves come in a variety of sizes that go with the above mentioned screws and some other odd sizes. These flanged sleeves simply described are a sleeve with a flange (washer) made onto one end. I use them to reinforce the screw holes drilled through cowls for mounting to the fuselage. This gives two surfaces protection, the inside diameter of the drilled hole and the outside surface where the screw head tightens down on the cowl. It also protects the threads of the nylon screw, which I find grip the tapped threads of wood much better than metal screws and are much lighter. These flanges can also be used where you have a drilled hole through wood sections that are too thick for a grommet, to accom-modate a music wire switch or needle valve adjustment extension. Another good place is for the wing mounting bolts. The ideas are endless.

Rubber tubing, such as vacuum line or neoprene fuel tubing really comes in handy for those odd shaped and larger openings that you may have to cut out for cylinder heads or exhaust pipes. This application, in my opinion, is mostly for cosmetic appeal, however it can prevent any chafing of fuel lines or electrical wiring. You should try to plan ahead to avoid any areas of chafing.

I have used this method for internal areas such as where the fuel tank sits in a ply cradle. Another good place is covering around an open cockpit. Simply make a longitudinal split in the hose and apply it to the edge of the area that you want to cover. Again, the uses are endless. Just let your creative juices flow!

All the above mentioned items can be glued in place, with the exception of the nylon flanged sleeves. These may not need to be glued.

I hope that I have passed along some information that may be helpful or useful to some of you. As I said in the beginning, not only do some of these items make you model look good, it can make them last a little longer.

Happy Flying and HAVE FUN! This is a hobby, you know!

from Tri-County Barnstonners
http://ourworld.compuserve.com/homepages/rpursley/tcbs.htm