Rivet tools

There's not all that much sheet metal work involved in restoring a classic airplane, but there is always some minor repair work that needs to be done, so you need basic rivet tools.

A modest rivet gun (a TP83) is shown in Photo 1.  In addition to the rivet gun you need rivet sets.  I have three: a 1/8" set, a 3/32" set and a flush set.  The flush set needs a different type of retainer, so you need two retainers: a beehive retainer and a quick change type. 

Of course you need a bucking bar.  There are dozens of different styles and you can even make your own.  But I have only ever needed one, a #647.  The 647 seems about the right size for general use and the small end will even buck the hard-to-get-at rivets on Taylorcraft wing ribs.

Photo 2 shows some nice to have (some would say required) items for riveting.  The air drill is one of my favorite tools, I got it for $10 on eBay.  It's old and its castings are worn smooth from years of use, but it still works great and I love the high pitched whine it makes. 

Next to the drill is a rivet cutter.  With one of these you can buy a batch of long rivets and cut them to length as needed.

Also handy is an assortment of cleco fasteners.  I have 8 each of 1/8" and 3/32" clecos.  Some folks who build aluminum planes buy hundreds of clecos and wish they had more, but I've never needed more than 8.  You'll need a cheap cleco pliers to install and remove the clecos.

Finally in the photo is a little bottle of Marvel Mystery Air Tool Oil.  I put 3 or 4 drops of oil in the air inlet of my air drill and rivet gun every time before I use them.

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Fiberglass Layup

All the materials and tools needed for a fiberglass layup are readily available at your friendly local WalMart.  Get:

      1. Fiberglass resin and fiberglass cloth and a can of car wax in the automotive department

      2. A couple of 2 inch chip brushes and a quart of acetone in the paint department

First, give the mold a couple coats of wax.  Car wax is not the very best mold release available, but it works fine and it's cheap.  Photo 1

Next, rough cut two pieces of glass cloth at least 1/2 inch larger all around than necessary to fill the mold cavity.  Use cheap sissors to cut the cloth.  Mix about 1/8 of a quart of resin with about 1/8 of the small tube of catalyst that comes with the resin.  While it's not necessay to be terribly accurate in your mixing ratio, it's a good idea to use a ruler and felt tip marker to number depth marks on the side of the resin can and the catalyst tube.  I found that roughly 1 inch out of the resin can needed about 1/4 inch out of the catalyst for a nice mix.  Photo 2.

Once the resin is mixed you have only 10 or 15 minutes (depending on temperature) to finish the layup, so from this point move quickly and smoothly.  Coat the inside of the mold cavity and about 1/2 inch around the outside with a thick layer of resin.  Some people just pour in some resin and then smear it around with the brush.  Photo 3.

Then stuff the first piece of pre-cut glass cloth into the wet mold.  Use the brush to push the cloth down into the resin, brush on more resin to completely wet out the cloth.  Areas that are not wet out will appear white.  Photo 4.

Put the second piece of glass cloth into the mold and wet it out like you did the first piece.  Then, using the brush in a stabbing, stippling motion to poke the resin into the cloth weave.  The idea is to get all the air bubbles out of cloth and get the cloth down snug against the mold surface.  Air bubbles will appear lighter than the rest of the layup.  Pay special attention to cornors and curved areas.  Photo 5. Keep working the layup until the resin starts to set up.  When the resin starts to set it will first get a jelly like texture, stop stippling at that point and throw away the brush. If you got any resin on your hands, a little acetone will clean it off. 

Let the layup cure for several hours or overnight, then use a putty knife to pry around the outside of the molding until the part pops loose from the mold.  Photo 6.

A bandsaw works great to trim the excess glass from the outside of the part.  Some folks use old tin snips or even sissors.  Photo 7.  Finally, finish with sandpaper, clean the surface with acetone and paint.

Link to Yoke Centerpiece,  Fiberglass Mold

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Fiberglass mold

Carl Ellis was kind enough to let me use his cowl bump to make copies in fiberglass.  Cowl bumps are needed to allow the use of shielded spark plugs, the shielded plugs are taller than the old style plugs and won't fit under the stock cowl.

The first step in making a fiberglass mold is to attach the original part to a plywood base.  I screwed the original to the plywood from underneath.  Then I coated the original and the plywood base with wax. Photo 1.  There's lots of great, expensive fiberglass mold releases and waxes available, but I used plain old car wax, the kind that comes in a can (Turtle wax).

Then I covered the original and base with a layer of fiberglass cloth.  I got my cloth and resin from WalMart.  It took about 1/4 of a quart can of resin to make the mold.  I used a cheap chip brush to apply the resin.  After the first layer of fiberglass I applied a second layer (right after the first layer, before the resin sets).  Then I set a plywood board into the wet fiberglass layers.  I'd cut out the plywood earlier so it would fit snugly down around the original part.  Finally I applied a third layer of fiberglass over the top of the plywood and original.  So I'd made a sandwich of: plywood base, original part, wax, 2 layers of fiberglass, another plywood, and a final layer of fiberglass.  Photo 2.

After letting the sandwich resin cure for a couple hours I used a putty knife to pry the sandwich apart at the wax-fiberglass boundary.  After mounting support rails on the second plywood piece I had the negative mold shown in Photo 3.

Link to Fiberglass Layup

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Brake rivets

The Taylorcraft uses "Shinn" brakes; mechanical, drum style brakes.  Parts are available from Skybound in Georgia.  I got a little kit of parts from them ("send me everything" is what I said) and after cleaning and painting my wheels I was ready to install the new brake linings.

There's two ways to attach linings.  The British method is to bed the linings in epoxy.  The Brits say this method is easier, stronger, keeps the linings from cracking, and you don't have to worry about the linings wearing down to the rivets. 

The other method is to use rivets through the lining and the drum.  The rivet folks argue that rivets are the original method and have worked for over 60 years and anyway epoxy could fail if it gets too hot.  The Brits reply is that, well, they didn't have epoxy 60 years ago or they would have used it and the epoxy bedding method has never failed in thousands of hours of hard use. 

Both methods appear to work just fine, both have their strong points.  So, of course, I used BOTH.  I bedded the linings in epoxy and then put rivets in too.

The epoxy method is by far the easiest way to go.  It took less than 30 minutes to epoxy linings into both wheels.  I used aeropoxy because of its thick, sticky character and reputed high temperature qualities.  I used C clamps and the brake shoes to clamp the linings in place while the epoxy set.

The rivets took a little more time.  First I chucked the wheel under the drill press and drilled holes slightly larger than the rivet shank through the drum and epoxy bedded lining.  Photo 1.  Then from inside the drum I counterbored the hole for the rivet head.  I used a 5/16 drill bit to remove most of the lining material for the counterbore, and then finished the flat bottom of the counterbore with a 5/16 brad point drill bit. No drill motor needed!  I was able to easily make a beautiful counterbore in the soft lining material just by turning the drill bit by hand.  Photo 2.  The brad point drill bit is shown on the left on Photo 3, an ordinary bit is on the right.  Brad point drills are available in most hardware stores.

The top of the rivet head needs to be about 1/16 below the surface of the lining.  Check your counterbore by slipping a rivet into the hole and checking the depth with the depth end of a dial indicator.  Photo 4.  The actual upsetting of the rivet is easily done with a special brake rivet tool (about $20 from Spruce), or the time honored punch and hammer method. Photo 5.

Link to Brake Spring Tool,  Tire Mounting,  Wheel Pants

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