Thanks for all the advice.  I even had a great deal offered to me on some extra tungsten that someone had.  It was 7/8" diameter, that made me nervous, drilling holes that large in my painted rudder.

 

My local welding shops have only 1/8" diameter.  Based on my preliminary weight calculations I needed about 30 ounces of tungsten.  I only need 10 ounces of extra weight, but I need to drill out 20 ounces of lead and replace the lead with tungsten, which is about 55% heavier than lead.  Doing the math, I would have needed about 24 7" rods (1/8") which would cost about $140 at the local welding shops.  Cut in half I would have to drill about 48 1/8" holes, YIKES!

 

So what I ended up doing is buying 2-3/8" diameter rods 12" long from www.tungstenco.com.  The cost was about the same but now I'm looking at drilling 6-8 holes instead of 48, much easier.

 

Some 20-20 hindsight.  Build your rudder as light as possible.  Don't get sloppy with flox, layups, wiring, etc. because it will be magnified when you work with the limited room in the rudder counterbalance arm.  Probably the easiest place to save weight is in the trim tab construction, build the tab light!

 

Another thing I would consider is buying some tungsten from the beginning and replacing some of the lead at the leading edge of the rudder counterbalance arm with tungsten.  Then you will have plenty of room for any additional lead down the road.

 

Thanks again for all your help,

 

Mike Easley