topeak-mtx-tortec-expeditionrack-adapter: introduce front_elevation_nominal

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/topeak-mtx-tortec-expeditionrack-adapter.scad b/topeak-mtx-tortec-expeditionrack-adapter.scad
index 6de109a600b3cc29e3525e0d401ed52322e7d0e1..f98e8aa5dcd95dafc303aa81f5e98d3f4e0edce6 100644 (file)
--- a/topeak-mtx-tortec-expeditionrack-adapter.scad
+++ b/topeak-mtx-tortec-expeditionrack-adapter.scad
@@ -21,6 +21,7 @@ rear_to_front_distance = 230; // rack cross rail (fam) to very front end
 rear_to_cross_rail = 43.05; // bolt centre to rail centre, rail to rear
 rear_bolt_to_front_bolt = 155.4;
 front_to_cross_rail = 43.05; // XXX // bolt centre to rail centre, rail to front
+front_elevation_nominal = 0;
 
 general_gap_y = 1.0;
 
@@ -101,6 +102,7 @@ brk_bolt_nut_top_y = -brk_nearbolt_recess_depth
 brk_bolt_nut_r = brk_bolt_nut_across_flats/2 / cos(360/12);
 
 function elevation_of_bolt_for(z) = rear_elevation_nominal
+  + front_elevation_nominal
   + (z - brk_block_z/2) * rack_shear_ratio;
 
 function rack_rail_y_of_elevation(elevation_nominal) =