Bob,

 

I just drilled my holes yesterday, no real problems at all.  I had to drill 6 3/8" holes 4 inches deep.  I found I needed to pull the bit all the way out and pick out some stuck lead in the bit.  Evidently the lead got hot enough to almost melt into the grooves in the bit.  You can tell it's time to clean the bit when it starts to get sticky.  I would say I had to clean the bit about every 1/2" of drilling.  I used a large drill, the old kind that plugs into the wall, it ran at a fairly slow speed compared to a cordless drill.

 

The tungsten rods cut fairly easily with my Sawzall, but a hack saw would cut them pretty well.  But I love power tools!  I beveled the ends of the tungsten to remove any burrs.

 

I used my calipers on the tungsten and picked the next larger bit, ended up being 25/64ths.  I drilled to make sure I had the tungsten rod recessed about 1/8-1/4".  I put a piece of tape on the bit at 4 1/8" to know when to stop.  I blew air in the hole after drilling to make sure it was clear of any loose chips of lead.  I mixed up some 5 minute epoxy, coated the tungsten rod and inserted it into the hole.

 

I drilled one hole at a time and glued in the rod before drilling the next hole.  I was concerned about the adjacent holes overlapping deep inside the rudder.  The hole would be wasted because I wouldn't be able to fully insert the rod, it would bump into the adjacent rod.  So I would recommend that you drill one hole at a time and glue in the rods as you go.  I only felt the drill bump into a tungsten rod once, but the drill drifted back into the lead, path of least resistance.

 

After inserting all the rods, I stood my rudder up on the top surface so the drilled surface is pointing up.  I drizzled some Jeffco in over the rods to let it run down into any gaps.  Then a layer of micro over the top to fill the holes.

 

Some sanding and paint touch up and I'll be finished.

 

Mike