poster-tube-lid: convert to oring: provide oring_[xy]_rad

diff --git a/poster-tube-lid.scad b/poster-tube-lid.scad
index 830370ef50f1fc0b8daa15221454f5812d8a0b5e..33d008f481287cf08c33029577e8d47c1bace1d5 100644 (file)
--- a/poster-tube-lid.scad
+++ b/poster-tube-lid.scad
@@ -50,8 +50,10 @@ bayo_inramp_z = bayo_entry;
 oring_mid_dia = oring_bore + oring_thick;
 oring_outer_dia = oring_mid_dia + oring_thick;
 
-seal_thick = (1 - oring_compress) * oring_thick/2
-  * (1 + cos(oring_upper_embed_angle));
+oring_y_rad = oring_thick/2 * (1 - oring_compress);
+oring_x_rad = oring_thick/2 / (1 - oring_compress);
+
+seal_thick = oring_y_rad * (1 + cos(oring_upper_embed_angle));
 
 side_height = rivet_posn + bayo_behind + rivet_thick/2;
 side_thick = rivet_tall + over_rivet_wall;