This is an Uilleann Pipe Synthetic Drone Reed System I came up with in July 1999.  It borrows ideas from many different people.  Ralph Hepburn, Ray Sloan, David Daye, John Liestman and many others.

A- Round drone throat.
 3/16 inch,(")  OD brass tube, a 3/4" length of it.  For Baritone and Bass.
 5/32" OD tube for the Tenor.
B- Attach tube A to tube D with hot melt glue.  Make sure there are no holes in the joint.
C- Air Hole Vent.
 Baritone and Bass.
 Two, 1/8" holes drilled into the top of the brass tube, close to where the end of the tongue will be.  These holes can be larger if you like or you can use a Dremel cutting wheel to make a slot.
 Tenor.
 Two, 3/32" holes drilled into the top of the brass tube.
D- Drone body.  Find the flattest side of the square tubing.  Some sides are convex and others are concave.  Polish the side to be drilled for the tongue with 400 and then 600 grit paper.  You can reverse the drone throat and tuning piston end for end to put the tongue into the normal position instead of the inverted position, but being inverted gives you a wider tuning range.
 7/32" OD square brass tube.  For Baritone and Bass.
 3/16" OD tube for the Tenor.
E- Two O-rings, 3/16" ID, 5/16" OD.  This would be for the Baritone and Bass.
 Two O-rings, 1/8" ID, 1/4" OD, for the Tenor.  A variation on this would be to have one o-ring at the nonplaying end of the tongue and a dental elastic at the position closer to the playing end of the tongue.  This elastic technique may put less contorting strain on the tongue, preventing it from being bent into a convex arc across its width on the top side.
You can also use just dental elastics but the o-rings keep the tongue in one place better.  You still want to be holding onto the tongue as you adjust the length of the tongue by the o-ring bridle.
F- This is the junction of the main body of the drone and the tuning piston.  You need to use a gasketing material that allows movement but prevents air leaks.  My old standby as with many adjustments related to drone reeds is to use Duco gum adhesive, known as Stik-Tak, used for hanging pictures on walls, weighting drone tongues and keeping drone reeds from falling off the end of drones.  This is even more important if you are trying to keep a synthetic reed in a synthetic pipe.
 To use it as a gasket, pull off a small ball of the Duco from the package, pull out a thin thread of it from the ball (it does this very well) and wind it right around the junction of the drone body and the tuning piston.  Use just one thread thickness of it.  Hold onto the gum as you pull the piston out of the drone body.  This should leave you with a small thread of gum at the end of the drone body.  Take your finger and slightly press this thread, from each of the four edges, into the drone body, enough so you know it will start to get caught when you put the piston back in.  Put the tuning piston back into the drone body.  The piston will grab onto the gum but also leave some behind, allowing the piston to move but not leak.
G-        This is the tuning piston.   Which is reversible.  You can put either end in.  The open end in gives you a lot of internal area making the drone flatter and mellower as you lengthen it out.  You can put the closed end in and really decrease the internal area of the reed, making it sharper and brighter.  Actually one of the reasons the tongue is inverted is to give you more adjustment area.  The inverted tongue slightly helps stability as you go up into the second octave.  It is much harder to kill the tongue on the edge of the drone stock, when it is inverted.  You can almost be asleep and not hurt the tongue as the drone is put in or removed from the stock.
H- This end of the tuning piston is closed off with a drop of hot melt glue.  Make sure there is no hole in any of the corners of the glue drop, and that there is no bump sticking out sideways.  Any bump would prevent you from turning the  tuning piston into the main body of the reed, inverting it, to continue changing the pitch and tone of the reed, as stated above.  The hot melt glue is easy to set up, repair or take off.
I- This is the styrene tongue,  I like .015" but you can try lighter and heavier.
 Get the styrene sheets from a craft shop or hobby shop that sells model trains.  It's used to make all sorts of stuff, from rail cars to buildings.  One package usually has three sheets, enough for a 10 year supply of reed tongues.  They'll probably have the brass tubing also.
 You can cut the styrene with a Sears Craftsman Handi-Cut, sharp scissors or any other cutter you feel comfortable with that will not deform the tongue in the process.  Put the tongue into position and then roll the o-rings onto it, into position.  Remember to stress the tongue up at an angle before trying to play it.  Hold the tongue in a concave, ski jump curve at about a 30 degree angle off  the drone body for about ten seconds.  See how it plays.  If it shuts off, hold it open longer.   If you really want it open put a little strand of 1/2" long by 1/16" wide, Teflon plumber's tape, under the tongue, close to the bridle.  If you have a hint of an air leak from the tongue, train it flat by rubbing it with the side of a pencil or pen on the top of the tongue to press it flat onto the body.   The teflon tape will be flattened but will still cause the tongue to raise away from the body of the drone.
 Another way I’ve seen to raise the tongue more permanently with a styrene tongue, is used by Ralph Hepburn, who makes highland Practice Pipes, at Bagpipes Galore in Scotland.  He has some valleys molded or cut into the drone top across its width.  The o-ring presses the tongue into this valley and raises it off of the drone body.  This can be done on the flat brass tube top by taking a triangular file and starting a small groove across the top of the reed where you would most likely expect the o-ring to sit.  Widen the groove with a needle file.  Make sure you don’t go so deep with the file as to cut through the tubing.  The o-ring will now press the tongue into the groove and cause it to rise.

 Ralph Hepburn uses a round nylon or delrin quill that has been machined off flat on the tongue side.  Much like a R.T. Shepherd GHB, drone reed.

Dimensions:
Bass Drone:
Throat-  3/16" round brass tubing, 3/4" long, 1/3 in the drone body, 2/3's out of it.
Drone Body- 2 1/2" long, 3/16" OD Brass square tubing.
Tuning Piston- 1 1/2" long, 3/16" OD Brass square tubing.
O-ring-  3/16" ID, 5/16 OD.
Holes-  2, 1/8".  Start 1/2" from the throat end of the square body.
Tongue- .015" thick, 1 1/4" long, no wider than the drone body.
Vibrating length-13/16"

Baritone Drone:
Throat-  3/16" round brass tubing, 3/4" long, 1/3 in the drone body, 2/3's out of it.
Drone Body- 2" long, 3/16" OD Brass square tubing.
Tuning Piston- 1 3/8" long, 3/16" OD Brass square tubing.
O-ring-  3/16" ID, 5/16 OD.
Holes-  2, 1/8".  Start 9/16" from the throat end of the square body.
Tongue- .015" thick, 1 1/8" long, no wider than the drone body.
Vibrating length-9/16"

Tenor Drone:
Throat-  5/32" round brass tubing, 1/2" long, 1/2 in the drone body, 1/2's out of it.
Drone Body- 1 1/4" long, 3/16" OD Brass square tubing.
Tuning Piston- 3/4" long, 5/32" OD Brass square tubing.
O-ring-  1/8" ID, 1/4" OD.  You might have more adjustability on this tongue if you also   try an orthodontic elastic on the o-ring position closest to the playing end of the   tongue. You can leave both sitting on the end of the quill and pull over whichever   one you want to use.
Holes-  2, 3/32".
Tongue- .015" thick, 3/4" long, no wider than the drone body.
Vibrating length-1/4"-3/8”
 Nothing about these dimensions is written in stone.  You can adjust the tuning piston to tune out or in further, invert it or cut off some length of the drone body.
 For stability and response I actually like to have the end of the tongues a little thinner.  Before I mount the tongue onto the quill under the o-rings, I thin out the top end of the tongue by running it over  400 grit paper 1-3 times.  Hold the last 3/16”-1/4”of the tongue down with your index finger and then pull it over the paper while the paper sits on a flat clean surface.  I like to use a flat jeweler’s file or metal and garnet fingernail file if I want to take small amounts off of the top end of the tongue while the tongue is in place on the quill. If you want to weight the tongue use a small ball of the Duco adhesive.
 To cut the brass tubing you can use a fine hacksaw, holding the tubing in the protected jaws of a vise, or a Dremel jig saw.
      Remember to try to keep everything about the drone reed airtight.  Any leaks in the system will cause the drone reeds to fluctuate tone more during changes in pressure.
 With the drone reed tuning slide mechanism repositioned long enough, you can try out hearing what your set of D drones sound like retuned to C.
 Happy droning,
  Eddie Damm

 Some folks have a hard time trying to pinch off the air when trying to bend the bag.
 This is a design for a bendable vinyl tubing stop valve for the Uilleann Chanter.  It consists of two nesting sizes of vinyl tubing.  When the narrower tube is bent 100-180 degrees, it pinches off the air supply to the chanter.  It can be left on during play or just used while tuning drones or regulators.

Dimensions:
 Narrow Tube:
  Length- 2 1/4”- 2 1/2”  inches
  Width - 5/16” ID x 7/16” OD

 Wider Tube:
  Length- 1 1/2”- 1 3/4”  inches
  Width- 3/8” ID x 1/2” OD

 The cost of the vinyl tubing at a hardware store should be under $1.  This will give you enough material to make extra for friends.
 The reason for cutting the tubing at an angle is that it is much easier to move the pieces together when there is a tight fit.
  Add some chapstick grease if you want the pieces to slide more.

 Happy piping,
  Eddie Damm
Copyright March, 2000 - 2008