[Steve D]

Finishing up the speaker:

I made the centering collar from four strips of 0.010 Teflon material which is what I had on hand and cut each piece successively longer to maintain the same length when wrapped around the pole piece.  This resulted in a thickness of nominally 0.040 and the gap appears to actually be closer to 0.038” and when compressed into the slot, fit nice and evenly tight all around.

   

With this arrangement I was able to easily press the pole piece back in and the resultant gap was beautifully uniform:

   

   

Next I used small strips of .007” paper to center the voice coil while I screwed the spider assembly in and glued the edges of the cone.  I had to remove the cone center cap to access the voice coil to insert the centering strips:

   

Continued in next post.

Steve D